Water Safety Plan
Guide
Worked Example of a Water Safety
Plan for a Small Supply Using
Chlorinated Groundwater
Version 1, Ref W2
January 2014
Citation: Ministry of Health. 2014. Water Safety Plan Guide: Worked
Example of a Water Safety Plan for a Small Supply Using
Chlorinated Groundwater, Version 1, ref W2. Wellington: Ministry of
Health.
Published in January 2014
by the Ministry of Health
PO Box 5013, Wellington, New Zealand
ISBN: 978-0-478-42774-5 (print)
ISBN: 978-0-478-42775-2 (online)
Previously published in 2002 as Public Health Risk Management
Plan Guide: Worked Example of a Public Health Risk Management
Plan for a Small Supply Using Chlorinated Groundwater, Version 1,
ref W2. This publication’s title and any reference within the text to
‘public health risk management plan’ were changed in January 2014
to reflect the December 2013 legislation change of the term ‘public
health risk management plan’ to ‘water safety plan’. No other
changes have been made to this document.
This document is available at: www.health.govt.nz
This work is licensed under the Creative Commons Attribution 4.0 International
licence. In essence, you are free to: share ie, copy and redistribute the material in any medium or
format; adapt ie, remix, transform and build upon the material. You must give appropriate credit,
provide a link to the licence and indicate if changes were made.
Contents
Introduction
1
Scenario
2
Water Safety Plan for Huia Flats Community
3
Barriers to Contamination
4
Risk Information Table
5
Improvements
21
Regular Checks and Maintenance Schedules
25
Contingency Plans
28
Water Safety Plan Performance Assessment
33
Reporting
34
Ref W2
Version 1, January 2014
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
iii
Introduction
This is one of two worked samples of a water safety plan (formerly known as a Public Health
Risk Management Plan, PHRMP) to help small water suppliers (those with 25 to 500 people)
prepare their water safety plans. Comments to help you understand how parts of this plan
were prepared are printed in italics and are headed as “Notes”.
The key processes in preparing water safety plans are:

Risk assessment
–
make a flow diagram of the supply
–
–
identify the elements in the supply so you can select the Guides you need
–
prepare a Risk Information Table for your supply that lists the preventive
measures, and checks on preventive measures that you should have in place to
reduce risk
prepare a list of improvements you need to make by comparing what you should
have (Step 4) and what you actually have
–
–
–

for each improvement needed, estimate the level of public health risk if the
improvement is not made
rank the risks for the whole supply according to their size (take into account the
seriousness of the health risk from each event, the likelihood of the event
occurring, and sum up all the risks from the various process elements).
Risk management
–
work out the resources (dollars, staff, expertise, equipment) needed for each
improvement
–
work out a final overall priority for each improvement taking account of the
level of health risk and the resources needed (Step 8) (use a cost-benefit
approach)
–
develop a three-year programme for managing each risk
–
–

make a list of the four “barriers to contamination” needed in a supply, and note
which of these your supply has, and which it does not have
prepare a summary of regular checks and maintenance that needs to be carried
out
prepare contingency plans that might be needed for your supply.
Plan evaluation and communication
–
prepare a list of instructions for reviewing the performance of the plan
–
prepare a list of instructions for reporting.
Ref W2
Version 1, January 2014
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
1
Scenario
This example is based on the imaginary community of Huia Flats, situated on the Canterbury
Plains. The source of the community’s water supply is a shallow well in the corner of a
paddock often grazed by dairy cows. The well-head is not properly sealed, but it is fenced
off from the stock. The soil cover is shallow, and the ground is quite porous in the area, with
the result that sometimes during heavy rains the water can become slightly cloudy and
discoloured.
A small shed next to the well-head contains the chlorinator. After the water is pumped from
the bore, it is chlorinated with sodium hypochlorite before being fed to a storage reservoir on
a nearby hillock. The reservoir has been well designed to keep out contamination. From the
reservoir, the water is gravity fed to the community. The pump used to dose the chlorine into
the water is well maintained, but the dose rate of the chlorine is controlled manually.
Chlorine measurements are not made very frequently. Consequently, when the water quality
is poor because of heavy rain, the chlorine dose rate is sometimes too low to allow the
chlorine to react with the “dirt” and still leave enough chlorine to kill germs.
The community, under an agreement with the local authority, has taken responsibility for
running its own supply. One of the local farmers has agreed with the Water Supply
Committee to look after chlorination of the water. Another farmer and the mechanic from
the local garage have responsibility for looking after the reticulation system, including
repairs. Both are uncertain about what has to be done to avoid contamination of the supply
when repairs to the reticulation are necessary. The Water Supply Committee has been very
careful to make sure that all situations where water might be sucked back into the supply
(backflow) have been identified, and air gaps, or backflow prevention devices, put in place.
2
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
Ref W2
Version 1, January 2014
Water Safety Plan for Huia Flats
Community
Flow diagram of the water supply
Storage
reservoir
tank
Shallow bore
Dosing
pump
Bore pump
Reticulation pipework
around the
community
Sodium
hypochlorite
storage tank
The individual Guides used in the preparation of this Plan were:

S1.1 Surface and Groundwater Sources

P1.3 Groundwater Abstraction – Bores and Wells

P7.1 Chlorination

P10 Pump Operation

D1 Post-treatment storage

D2.1 Construction materials

D2.2 System Pressure

D2.3 Operation (reticulation network)

D2.4 Backflow prevention

G1 Staff Training

G2 Monitoring
Ref W2
Version 1, January 2014
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
3
Barriers to Contamination
The barriers to contamination in place in the Huia Flat Community supply, and the concerns
about how well they work, are summarised in the following table:
Barriers to:
Comment
Stop contamination of raw water
The well is shallow and the well-head is unsealed. These
features, and the porous nature of the ground mean that
barriers to contaminants entering the raw water are limited.
Remove particles from the water
There are no barriers to remove particles.
Kill germs
Chlorination – manual control of the chlorine dosing may
result in too little chlorine being added to the water to
disinfect it properly when water quality changes because of
rain.
Prevent recontamination after
treatment
Important steps to stopping contamination after treatment
have been taken:

the storage reservoir is well sealed against entry of
contaminants

the water supply is totally enclosed after the reservoir

measures to prevent backflow are in place where
necessary.
However, poor knowledge of the procedure for making pipe
repairs may allow contaminants to get into the water.
Notes on the barriers to contamination
Look through the Risk Information Table (next section) to determine which barriers to
contamination your supply has, and how effective they are likely to be. Preparing a table like
that above will help you to identify barriers your supply is missing.
4
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
Ref W2
Version 1, January 2014
Risk Information Table
Checking water quality
Checks for germs are the most important checks on water quality you can do. As a result,
these checks could be listed many times in the following table. To keep the table as simple
as possible, the checks for germs are not included, but remember that the Drinking-Water
Standards for New Zealand require that:
Checks for germs (the test is usually for a germ called E. coli) should be made at least once
a month in the water:

directly after chlorination

and in the reticulation network.
If E. coli is found in either case, there is a problem that needs to be investigated. You may
also wish to take a sample of water before treatment from time to time, to check on the quality
of water entering your supply.
If something happens to make you think animal or human excrement may have got into the
water, you should immediately take samples to check whether there are germs in the water.
Where you take the samples will depend on what has happened.
If you are unsure about what you have to do when checking for germs, contact a health
protection officer with your local District Health Board.
Free available chlorine (FAC) measurements are also important in chlorinated water. If you
have a satisfactory FAC concentration in the water all the time, it is very likely that the germs
you check for each month will be absent. The Drinking-Water Standards for New Zealand
do not require you to make these measurements if you are already doing monthly checks for
gems.
Where possible, the checks listed in the risk information table are those that can be made
without having to test the water, but you can do checks to test the water if you are worried
about the water quality.
Abbreviations: DWSNZ – Drinking-Water Standards for New Zealand; Guidelines – Guidelines for Drinking-water
Quality Management for New Zealand; MAV – Maximum acceptable value – see DWSNZ:2000; Council –
Ref W2
Version 1, January 2014
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
5
regional/district council or unitary authority; FAC – free available chlorine; HTH – high test hypochlorite (chlorine
tablets composed mainly of calcium hypochlorite).
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
The Source Water
Event: CONTAMINATION GETS INTO THE WATER UNDER THE GROUND
Possible hazards: Germs, pesticides, other chemical contaminants.
Level of risk: High

C2.1.1
Some of the water
reaching your well
has been
contaminated by
such things as:

contaminated
site

landfill

septic tank

agricultural
activity

mineral
deposits

geothermal
activity.

6
Find out all you can
about what might
contaminate
groundwater in your
area. This will help
you decide where to
put the well, and
what to test for
when checking the
water quality.
– ask the council
if they can tell
you about
possible
sources of
contamination
in the area that
may affect your
water quality
– the council may
not be aware of
all possible
contamination
sources. Check
for yourself by
inspecting the
area within 2km
of your well
– get help from
environmental
health officers
in identifying
sources of
contamination.





Take samples once
a year to check on
the quality of water
from your bore.
You may have to
sample more often
if you find
contaminants.
Record the results, 
so that you can spot
changes in water
quality by
comparing them
with earlier results.
Concerns about
landfill:
– germs
(E. coli)
– arsenic
– boron
– alkalinity
– conductivity.

Concentration
of any of the
chemicals
tested for is
more than 50%
of its MAV.

Contamination
from a landfill
can cause an
increase in
alkalinity and
conductivity,
(which have no
MAV).
Concerns about
contaminated site:
– depends on
the
substances in
the site.

Concerns about
septic tanks:
– germs
(E. coli)
– nitrate.
Counts of
E. coli are
occasionally
found in 100 ml
of water.

Get advice on
treating the
water to remove
the
contaminants.

Think about
finding a new
source of water.

Check with the
council whether
a change in a
discharge
consent could
help reduce the
contamination.
Concerns about
agricultural
activities:
– pesticides
– herbicides.
(NB. pesticides
are only likely to
be a concern if
large amounts are
used, or the
ground is porous.)
Concerns about
mineral deposits:
– heavy metals
(select those
ones in any
known
mineral
deposits).
Concerns about
current or
historical
geothermal
activity:
– boron
– fluoride
– arsenic.
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
Ref W2
Version 1, January 2014
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
Water abstraction (getting water out of the ground)
Event: NOT ENOUGH WATER AVAILABLE
Possible hazards: Germs or chemicals that get into the water because of low system pressure; hazards
associated with poor hygiene.
Level of risk: High
C2.2.1

Drought.
C2.2.2
Start water
conservation as
soon as water
shortage becomes
likely.

How much
water is used.

Water pressure. 

Plan to use another
source to provide
extra water.

Obtain a new

resource consent
that will allow you to

draw more water
from the well.
Resource consent
stops you from
drawing more
water.

How much
water is used.


Find another
water source.
Complaints about
low pressure.

Get a bigger
storage tank.

Complaints about
low pressure.
Obtain a new
resource
consent.

Water use near
maximum
allowed.
Find another
water source.

Get a bigger
storage tank.

Water use near
maximum well
can deliver.

Drop in water
pressure.
Water pressure. 

Plan to use another
source to provide
extra water.
Drop in water
pressure.
Event: CONTAMINATED WATER GETS INTO THE WELL
Possible hazards: Germs; chemicals (eg, manganese, nitrate).
Level of risk: High
C2.3.1

Require the
contractor to follow
the NZ Drilling
Standard when
drilling the well.

Appearance of
water.

Cloudy or
coloured after
rain.

Pull out the
casing and
repair or
replace.

Get advice on which
casing material to
use if the water is
corrosive.1

Do tests to find out
the maximum rate
water can be safely
drawn from the
aquifer,2 and do not
exceed this rate.

Pumping rate.

Pumping rate is
more than the
maximum
acceptable rate
(see preventive
measure).

Try to reduce
water usage.

Reduce
pumping rate.

Require the
contractor to follow
the NZ Drilling
Standard when
drilling the well.

Well-head seals
absent or in poor
condition.


Check the wellhead
is properly sealed
and constructed in
conformance with
figure 3.6 of the
Guidelines.
Make changes
to the well-head
to meet the
requirements of
the NZ Drilling
Standard.
Poor joints or
cracks in the well
casing; corrosion
of the casing.
C2.3.2
Contaminated,
shallower
groundwater is
drawn into the
well.
C2.3.3
Well head poorly
designed or
constructed.
Condition of
seals around
well-head.

1
Ask companies who manufacture or sell well casings for advice on the type of material they would recommend
where the water is corrosive. You may have to ask a well-drilling company for the names of suitable companies
to ask.
2
Contact your local regional council for advice about how to do simple tests, or who can carry out these tests.
Ref W2
Version 1, January 2014
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
7
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
Event: CONTAMINATED WATER GETS INTO THE WELL – cont’d
C2.3.4

Provide protection
against damage by
stock and humans.

Do regular visual
checks of the well
head for damage.

Check for sources
of contamination
when choosing the
well location.

Put a fence around
the well-head, at
least 10m from it (to
keep stock away).

Avoid low ground
when choosing the
well location.

If possible, build
drains to stop water
pooling around the
well head.

Contour the ground
around the well,
using new fill or
concrete, so that it
slopes away from
the well.

Put a backflow
preventer on the
pump.
Well-head
damaged.
C2.3.5
Well is too close
to contamination
sources.
C2.3.6
Well located in
low ground.
C2.3.7
Contaminants
back-siphoned
from the mains.



Condition of
well-head.

See C2.1.1.
Well-head
damaged.
See C2.1.1.

Repair
well-head.

Build protection
around the
well-head.

Build a fence
around the well
head.

If possible,
move the
contamination
source.

What happens to
water after rain?

Pooling of water 
around well
head after rain.

Does the
well-head have a
backflow
preventer?

No backflow
preventer.

Put drains in
place.
Install backflow
preventer.
Event: NOT ENOUGH WATER CAN BE DRAWN FROM THE WELL TO MEET DEMAND
Possible hazards: Germs or chemicals that get into the water because of low system pressure; hazards
associated with poor hygiene.
Level of risk: High
C2.4.1

Well-head or
pump damaged
by animals.
Regularly inspect
the well-head.

Fence off the
well-head to keep
stock at least 10m
away.
C2.4.2

Inspect the well

regularly, especially

after natural events.
Well-head or
pump damaged
by natural event
(flood, landslide
etc).
8



Low, or no, flow.

No fence in place.

Damage to
well-head.
Flood levels.

Low, or no, flow.
Flow from
well-head.

Damage to
well-head.
Flow from
well-head.
Where possible,
provide protection
to reduce damage
during extreme
weather.
Example Water Safety Plan:
Small Chlorinated Groundwater Supply

Start regular
inspections.

Build fence.

Check whether
more protection
can be
provided.

Consider finding
another source
of water.
Ref W2
Version 1, January 2014
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
Event: NOT ENOUGH WATER CAN BE DRAWN FROM THE WELL TO MEET DEMAND – cont’d
C2.4.3

Pump doesn’t
work.
C2.4.4

Power failure.

C2.4.5
Maintenance
schedule.

Flow.
Regularly check
power lines and
cables for damage.

Flow.

Maintenance
falling behind
schedule.

No, or low, flow.

No flow.

Alarm indicates
power failure.
Install an alarm to
indicate power
failure.
Install stand-by
generator.

Build a lockable
security fence
around the
bore/well-head.


Install an intruder
alarm.

Require the well

driller to develop the
well properly by
following the
procedures in NZ
Drilling Standard.

Plan to regularly
clear the screens of
sand/debris. (Get
advice on how.)
Well screens3 are
clogged.
3


Vandalism/
sabotage.
C2.4.6
Use manufacturers
maintenance
guidelines to
prepare a
maintenance
schedule for the
pump.
Well-head and
pump.
Flow from the
well-head.

Prepare
maintenance
schedule.

Discuss power
problems with
the power
supplier.

Obtain a standby generator.

Damage to the
well-head.

Build a security
fence.

Signs that
someone has
tried to get to
the well-head.

Install an alarm.

Low flow.

Start screen
cleaning
programme.
Screen: Filter used to keep sediment (sand, gravel etc) from entering the well.
Ref W2
Version 1, January 2014
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
9
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
Chlorination (sodium hypochlorite)
Event: NOT ENOUGH FREE AVAILABLE CHLORINE
Possible hazards: Germs not killed.
Level of risk: High

C2.5.1
Chlorine dosing
system does not
operate properly:
–
dosing pump
not working
–
dosing pump
unable to
meet

maximum
required dose
–
tubing
blocked.
C2.5.2
Reduction in
water quality is
not matched by
an increased
chlorine solution
dose.4
4

Regularly maintain
the dosing pump
(including the pump
head). Keep
records.

FAC.

Maintenance log.
Check that the
pump is suitable for
use with chlorine
solution.
Check that the
pump is capable of
delivering the
maximum dose rate
needed.

Put filters in pump’s
suction line so that
particles do not
block pump valves.

Install a flow meter
for the chlorine
solution so that the
flow of the chlorine
solution can be
checked by eye.

Make FAC

measurements as

often as necessary
to make sure that
enough chlorine is
added to the water
to provide a chlorine
residual of
0.2 mg/L.
(Measurements will
probably have to be
made more
frequently after
rain.)
FAC.

FAC
concentration
less than
0.2 mg/L in the
water in the
reticulation
network.

No
maintenance
being done.

Blockage of
tubing
occurring.

FAC
concentration
less than
0.2 mg/L in the
water in the
reticulation
network.
Appearance of
water.

No change in
chlorine dose,
but water more
cloudy or
coloured.

Identify the
reason for the
dosing system
not working,
make repairs
and take steps
to stop the
problem
happening
again.

Dose the
storage
reservoir with
chlorine (HTH,
or sodium
hypochlorite) by
hand until the
chlorination
system is
working again.

Monitor the
water quality
more closely
during rain.

Dose the
storage
reservoir with
chlorine (HTH
or sodium
hypochlorite) by
hand to bring
the FAC
concentration
up to the right
level.
Contaminants in poor quality water react with chlorine so there may be no chlorine left to kill germs. To make
sure there is enough residual chlorine left after it has reacted with the contaminants, more chlorine has to be
added when the water quality is poor.
If the chlorine dose has been increased because of poor quality water, and if the water quality later improves
without the chlorine dose being adjusted accordingly, the FAC concentration may become too high.
10
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
Ref W2
Version 1, January 2014
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
Event: NOT ENOUGH FREE AVAILABLE CHLORINE – cont’d
C2.5.3

Chlorine supply
runs out


C2.5.4

The chlorine
concentration in
the dosing

solution is low.
C2.5.5

Power failure.
Keep records of

chlorine solution
use to help estimate
how long a batch is

likely to last.
Volume of
chlorine solution
in container.

FAC.
Keep a spare
container of chlorine
solution on site.

Put an alarm on the
chlorine solution to
warn when it is
close to running out.
Keep chlorine
solution dark and
cool.
Check FAC
concentration
leaving treatment
plant when a new
batch of chlorine
solution is started.
Regularly check
power lines and
cables by eye for
damage, and get
the power supplier
to make repairs if
necessary.

Install an alarm to
indicate power
failure.

Install standby
generator.
Ref W2
Version 1, January 2014

FAC.

Storage
conditions for the
chlorine solution.

Certificate of
analysis from the
chemical supplier.

Chlorinator
operation.

Electricity supply.


Too little

chlorine solution
left for a new
supply to arrive
before it runs

out.
FAC
concentration
less than
0.2 mg/L in the
water in the
reticulation
network.
Install an alarm to
warn that the
supply is running
out.
Dose the storage
reservoir with
chlorine by hand
(HTH, or sodium
hypochlorite) until
a new supply of
chlorine solution
arrives.

Get a spare
container of
chlorine solution.
FAC

concentration
less than
expected in the
water going into
the storage

tank.
Increase the
chlorine solution
dose until a new
batch can be
obtained.
Chlorine
solution is kept
in the sunlight
and allowed to
get warm.
Get a new batch
of chlorine
solution.

Dose the storage
reservoir with
chlorine by hand
(HTH, sodium
hypochlorite) until
a new supply of
chlorine solution
arrives.

Think about
getting chlorine
solution from a
different supplier.

Chlorine
solution pump
not operating.

Discuss power
problems with the
power supplier.

General signs
of a power
failure.

Obtain a standby
generator.

Alarm indicates
power failure.
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
11
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
Event: NOT ENOUGH FREE AVAILABLE CHLORINE – cont’d
C2.5.6

Regularly check the 
water’s pH.

From time to time
send a sample to an
approved laboratory
for a pH
measurement to
check that the
results you are
getting are reliable.

Have staff trained to 
take samples and
record the results.

Draw up a schedule
for taking samples.

Have staff trained
to: take samples,
measure the FAC,
and record the
results.
pH is too high.5
C2.5.7
FAC samples
taken
incorrectly (see
C2.11.1).
C2.5.8
Problems with
FAC
measurement:
–
wrong
method
–
incorrect
calibration
–
test
reagents
gone off.

pH.

pH above 8.0.

Records of FAC
analysis results.

Wrong results

from monitoring.
Identify training
needed by staff.
Records of FAC
analysis results.

Wrong results

from monitoring.
Identify training
needed by staff.

FAC

concentration is
more than
2.5 mg/L in the
water in the
reticulation
network.
Monitor the water
quality more
closely.

Chlorine taste
and smell of the
water stronger
than usual.
Get advice on the
right chemical to
use to adjust the
pH, and how and
where it should
be added to the
water.
Event: TOO MUCH FREE AVAILABLE CHLORINE
Possible hazards: Chlorine; possibly disinfection by-products.
Level of risk: Low-moderate

C2.6.1
Change in
water quality is
not matched by
a change in
chlorine dose.4
4
Make FAC

measurements as

often as necessary
to make sure that
the chlorine solution
dose matches the
changes in water
quality.
FAC.
Taste and smell
of the water.
Contaminants in poor quality water react with chlorine so there may be no chlorine left to kill germs. To make
sure there is enough residual chlorine left after it has reacted with the contaminants, more chlorine has to be
added when the water quality is poor.
If the chlorine dose has been increased because of poor quality water, and if the water quality later improves
without the chlorine dose being adjusted accordingly, the FAC concentration may become too high.
5
Chlorine is a poor disinfectant at high pH. Using sodium hypochlorite will tend to push the pH up. Dosing acid
can be used to bring the pH down. Sodium bisulphate, or hydrochloric acid could be used, but you should get
advice from the company selling the dosing equipment about safe handling of these substances.
12
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
Ref W2
Version 1, January 2014
Preventive
measures
Causes
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
Event: TOO MUCH FREE AVAILABLE CHLORINE – cont’d
C2.6.2

Chlorine level in
dosing solution is
too high because:
– concentration in
supplied batch
is too high

– of addition or
spillage of
chlorine
compound into 
dosing solution.
Check FAC
concentration
leaving treatment
plant when each
new batch of
chlorine solution
is started.

FAC.

Certificate of
analysis from
the chemical
supplier.

Train the staff in
handling
chemicals.
Labelling of
chemical
containers.


Make sure all
chemical
containers are
clearly labelled.
FAC

concentration is
more than
2.5 mg/L in the
water in the

reticulation
network.
Containers not
labelled or
wrongly
labelled.
Reduce the chlorine
solution dose until a
new batch can be
obtained.
Dilute the dosing
solution with
unchlorinated water.

Get a new batch of
chlorine solution.

Properly label
chemical
containers.

Think about getting
chlorine solution
from a different
supplier.
Post-treatment storage
Event: NOT ENOUGH WATER IN POST-TREATMENT STORAGE TO MEET DEMAND
Possible hazards: Germs or chemicals that get into the water because of low system pressure; hazards
associated with poor hygiene.
Level of risk: High
C2.7.1

See C2.2.1, C2.2.2 and C2.4.
Too little water
available from the
source.
C2.7.2

Post-treatment
storage tank/
reservoir too small.
Build another
storage tank.

Encourage water
conservation
when water use is
likely to be high.
C2.7.3


Water use.

Need for water 
use restrictions.

Storage levels
too low.
Introduce water
restrictions.
See C2.4.
Water cannot be
drawn from the well
and pumped to
storage.
C2.7.4
Post-treatment
storage leaking.

Regularly inspect
tanks for signs of
leaks.
Ref W2
Version 1, January 2014

Storage level. 
Storage level
drops faster
than you would
expect from the
rate at which
water is used,
and the rate at
which it goes
into the tank.

Find the leak, fix it,
and try to find out
why the leak
started.
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
13
Preventive
measures
Causes
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
Event: CONTAMINATION GETS INTO THE STORAGE TANK
Possible hazards: Germs; arsenic, copper, chromium (all three metals from run-off from tanalised timber roof).
Level of risk: High
C2.8.1

Animals or birds
getting into storage
tank.
Ensure the tank is 
covered.

Put mesh on
vents, overflow,
etc.
6
Dead animals
found in tank.

Mesh/grills
disturbed by
animals to get
into the tank.

Remove animal
remains and
disinfect tank.6

Replace or provide
mesh where
necessary.
Check inside of
tank monthly.


Remove
vegetation near
tanks.
Unpleasant

taste and odour.

Water cloudy.

Unpleasant

taste and odour.

Water cloudy.

Sediment
covers bottom
of tank.
Put a slippery
metal band
around the tank
so that animals
can’t get into
wooden tanks
from the ground.
C2.8.2

Accumulation of
sediment in tank.
Clean the tank
each year.

Use two storage
tanks, the first
feeding into the
second, and draw
water from the
second (this
reduces sediment
being carried
through into the
reticulation).

Vandalism/
sabotage.



C2.8.3
Monthly tank
inspection.
Take steps to
stop people
getting access to
the tank (fences,
locked hatches).


Monthly tank
inspection.
Regular

inspection of
tanks for
signs of
anyone
having tried to
get into the
tank.
Prepare a timetable
for checking the
tank.
Start inspection and
cleaning
programme.

Install a second
tank.
Signs that

someone has
got into the tank
without
permission.
Fence tank, and
provide lockable
hatches.
1 mg/L of chlorine for clean water, possibly up to 5 mg/L if water is poor quality. About 1 teaspoon of bleach per
150L of water gives a concentration of about 1 mg/L.
14
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
Ref W2
Version 1, January 2014
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
Event: CONTAMINATION GETS INTO THE STORAGE TANK – cont’d
C2.8.4

Water from the
roof gets into the
tank.
Roof should drain
away from any
openings.

Stop people walking
on the roof. If
necessary for
maintenance, their
footwear must be
cleaned.
C2.8.5
Water is siphoned
back into the tank
from drains.
Design of
tank roof.

Check for
leaks in roof.

Make sure hatches
are designed to stop
water getting in.

From time to time
check roof for leaks
that might let water in,
and repair promptly.

Install internal liner for
wooden tank roofs.

Inspect the tank every 
1–5 years (depending
on its age and risks
caused by its
location).
Contaminated
groundwater gets
into the tank (for
in-ground tanks)
C2.8.6


Repair leaks
promptly.

Line the tank with a
suitable waterproof
material.

Make sure there is an
airgap between the
tank overflow and the
sewer or stormwater
drain it is connected
to.
Ref W2
Version 1, January 2014
Check for
leaks.

Change in
water quality
following rain.

Repair leaky
joints, cracks, or
hatches promptly.

Flaws in the
roof design.


Leaks in the
roof.
Check that the
FAC is at least
0.2 mg/L, and if
not dose the
storage reservoir
with chlorine by
hand (HTH, or
sodium
hypochlorite).

Unexpected

change in water
quality.

Leaks found
during
inspection.



Overflow
construction.


Complaints of
taste and odour.
Direct
connection
between
overflow and
drain.
Repair leaks
promptly.
Turn off flow into
and out of the
tank and add
enough chlorine
(HTH or sodium
hypochlorite) so
that the FAC is at
least 0.2 mg/L.

If there is gross
contamination of
the water dump it,
clean the tank
and refill.

Disconnect any
direct
connections.

Turn off flow into
and out of the
tank and
chlorinate until
checks show that
E. coli cannot be
found in 100ml.

If there is gross
contamination of
the water dump it,
clean the tank
and refill.
Water looks
cloudy.
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
15
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
Event: WATER PASSES THROUGH THE TANK TOO QUICKLY FOR PROPER DISINFECTION
Possible hazards: Germs not killed.
Level of risk: High

C2.9.1
Get advice on the size
and design of tank
needed to keep water in
the tank long enough for
proper disinfection.


Tank should fill at the top
and empty at the bottom.


Get advice on the need
for baffles to force the
water through a longer
route from inlet to outlet.
Tank is too
small.
C2.9.2
Design of
tank allows
water to
“short circuit”.
Compare
actual size of
tank with
smallest
satisfactory
size.

Tank smaller
than smallest
satisfactory
size.

Get advice on
design of tank or
the need to
increase its size.

Unexplained
fluctuations in
water quality.
Tank design.

Tank design not 
satisfactory.

Unexplained
fluctuations in
water quality.
Get advice on
design of tank or
the need to
increase its size.
Reticulation system
Event: CONTAMINATION ENTERS THE WATER AFTER TREATMENT
Possible hazards: Germs; chemicals.
Level of risk: High

C2.10.1
Breaks, leaks
or damage to
the pipes.
16
Where you can see pipes, 
check them for signs of
damage or breaks every
six months. If the pipes
could be damaged by
floods or slips, also check
after heavy rain.

Reduce the corrosiveness
of the water by placing
marble chips in the
storage tank, for example.

If selecting piping
materials, pick materials
that are less likely to
corrode.

Where pipes are above
ground, make sure they
are protected from
accidental damage.

Require subcontractors to
report any damage to
water supply pipes they
cause.

Avoid very high water
pressures and sudden
changes in water
pressure; these cause
stress on the pipes.
Water
pressure at
taps.
Example Water Safety Plan:
Small Chlorinated Groundwater Supply

Signs of leaks
found during
checks.

Much more
water used than
expected.

Rust-coloured
water, or water
with a bitter
“iron” taste.

Leaks appear
often.

Burst pipes.

Start checking the
pipes regularly.

Get advice on
how to make the
water less
corrosive.

See if you can
provide better
protection for the
pipes.
Ref W2
Version 1, January 2014
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
Event: CONTAMINATION ENTERS THE WATER AFTER TREATMENT – cont’d
C2.10.2

Contaminants
enter the
water as the
result of
repairs to the
reticulation.
C2.10.3

Record where the repair
was made, and who made
it.

Use a properly qualified
contractor to lay pipes.
Water pipes
are laid too
close to the
sewer.
C2.10.4
Illegal crossconnection to
the water
supply.
Get a properly qualified

person to make any
repairs. This person

must:
– thoroughly wash their
hands before making 
the repair, and clean
or change their
footwear
– not do the work if they
have recently had
diarrhoea or vomiting
– clean and disinfect
with chlorine solution
all tools (very
important if they have
also been used with
wastewater)
– flush the repaired pipe
to remove any dirt
– fill the repaired
section of pipe with
chlorinated water,
allow it to sit, then
thoroughly flush.


Make sure only properly

qualified people make
connections to the supply.
Appearance
of the water.
Repair
records.
After the
repair is
made:
– E. coli
(germs)
– FAC.

One or more
E. coli germs
found in 100 ml
of water.

Employ a
registered
plumber to make
the repairs.

FAC

concentration
must be at least
0.2 mg/L.

Water is
discoloured, or
tastes or smells
bad.
Check that the
FAC is at least
0.2 mg/L, and if
not, dose the
water with
chlorine by hand
(HTH or sodium
hypochlorite).

People who
drink the water
get sick.

Repair is not
recorded.
Plans

showing
locations of
sewers and
drinking-water
pipes.
Inspection of
work by a
properly
qualified
person.

Crossconnections
found.

People who
drink the water
get sick.

Ref W2
Version 1, January 2014
Plans show the
sewer and
drinking-water
systems run
close together.
Water is
discoloured, or
tastes or smells
bad.

Get contractor to
relocate pipes to
make sure there
is enough
separation.

Check that the
FAC is at least
0.2 mg/L, and if
not, dose the
water with
chlorine by hand
(HTH or sodium
hypochlorite).

Employ a
registered
plumber to make
connections.

Check that the
FAC is at least
0.2 mg/L, and if
not, dose the
water with
chlorine by hand
(HTH or sodium
hypochlorite).
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
17
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
Event: CONTAMINATION ENTERS THE WATER AFTER TREATMENT – cont’d

C2.10.5
Contaminants
are sucked
into the
reticulation
(“backflow”).

Check the reticulation for
places where water can
be sucked back into the
drinking water if the
supply pressure drops.

Where backflow is
possible, make sure that
one of the following is in
place:
– backflow-prevention
device
– double check valve
– air gap.
Check the
supply for
places where
backflow
prevention is
needed.

Check shows

there are places
where backflow
may occur, but
there is no
device to
prevent it
occurring.

Water is
discoloured, or
tastes or smells
bad.

People who
drink the water
get sick.

Changeable
water pressure.

Low water
pressure.
(Some places were these
devices may be needed are:
swimming pools; stock
troughs; boilers; tanks used
for preparing agrichemicals;
school laboratories.)
C2.10.6

Drop in water
pressure due
to, eg:
Make sure there is a
reserve of water for firefighting.

Use manufacturers
maintenance guidelines to
prepare a maintenance
schedule for the pump.

Encourage water
conservation.

Put the storage tank up
high so water is supplied
under gravity.

Require any contractor

doing work on the supply
to use approved materials
for pipes and other
fittings.
–
pumps
not
working
–
sudden
high
demand
for water
(eg, fire).
C2.10.7
Construction
materials
affect water
quality.
C2.10.8

Flush new sections of
pipe.

Replace sections of pipe
that are starting to fail.

Use materials with a
smooth surface so germs
cannot easily attach.

Regularly inspect
backflow prevention
devices, and exposed
pipes or valves.

Where possible, provide
lockable enclosures for
parts of the supply that
might be intentionally
damaged.
Vandalism or
sabotage.
18


Water
pressure.
Appearance
and taste of
the water.
Check for
signs of
damage.
Example Water Safety Plan:
Small Chlorinated Groundwater Supply

Cloudiness or
particles in the
water.

Complaints of
taste in the
water. (Most
new plastic will
result in taste
for a start, but
this should
disappear over
a week or so.)

Signs of
damage to a
part of the
supply.

Water is
discoloured, or
tastes or smells
bad.

People who
drink the water
get sick.
Where needed,
install devices to
stop backflow.

Make sure
backflow
preventers are
installed at
properties where
there may be a
problem (see
C2.10.5).

Improve water
conservation
measures.

Replace
substandard
materials with
approved
materials.

Repair or replace
damaged
components.

Provide protection
to stop future
damage.
Ref W2
Version 1, January 2014
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
Monitoring
Event: WATER TEST RESULTS UNRELIABLE7
Possible hazards: Germs, chemicals.
Level of risk: High
C2.11.1

Samples
taken
wrongly.

Get advice from a health 
protection officer, or
laboratory, about the
sampling you need to do
to comply with the
DWSNZ. You need to
know:
– where to take the
samples
– how often samples
have to be taken
– how to take the
samples so that they
are not contaminated
– what to do if a sample
shows the water
quality is poor. (This
table will help with
this.)
Check that
the sampling
plan is being
followed.

Sampling does
not meet the
requirements of
the DWSNZ.

Obtain a copy of
the DWSNZ8 to
help you
understand the
monitoring you
have to do.

Get more advice
from a health
protection officer
to discover why
there are
problems with the
monitoring.
Prepare a sampling plan
to record when and where
samples need to be
taken, and who is to take
them.
7
The laboratory may also make mistakes, but the concerns here are mistakes that the water supplier can tackle.
8
Copies of the Drinking-Water Standards for New Zealand can be obtained from the Ministry of Health’s website
(http://www.moh.govt.nz) or from Wickcliffe Ltd, phone (04) 496 2277.
Ref W2
Version 1, January 2014
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
19
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
Staff training
Event: SUPPLY NOT PROPERLY OPERATED OR MANAGED
Possible hazards: Germs, chemicals.
Level of risk: High
9
C2.12.1

Staff not
trained well
enough.
Get experienced staff to
pass on their knowledge
to new staff.

Make sure staff
understand:
– how the supply
operates
– how it has to be
maintained
– what to look for to
check it is operating
properly
– who to contact if they
need help.

Find out about staff
training courses.9

Put some money aside to
help pay for staff training.

How well the
supply runs.

Things happen
in the supply
that result from
poor staff skills
and/or
knowledge.

Check with the
staff if there are
things about the
system they do
not understand.

Make plans to get
the staff the
training they
need.

Find enough
money to train the
staff.
New Zealand Water and Waste Association (NZWWA) can provide this information: PO Box 13-880, Onehunga,
Auckland, Ph: 09 636 3636; Fax: 09 636 1234; Email: water@nzwwa.org.nz; website: http://www.nzwwa.org.nz.
20
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
Ref W2
Version 1, January 2014
Improvements
Comparison of the information in the Risk Information Table with the actual supply, shows
the following problems:

The well-head is not properly sealed. This may allow contaminants to run down into
the well, especially if surface flooding should occur.
Action needed: Build a shed around, ensuring that the well-head is sealed and the shed
floor used as the concrete pad around the well. (Full details are given in the Guidelines
for Drinking-Water Quality Management for New Zealand, Ministry of Health).

There is presently no way of removing particles from the water. This will allow the
larger germs, such as Giardia and Cryptosporidium, to pass through the treatment to
the consumers. Cloudiness in the water will also reduce the effectiveness of the
chlorine.
Action needed: A filtration system, probably cartridge filtration, needs to be installed.

Chlorine addition is presently manually controlled and dosing does not always keep
up with changes in water quality. As a result, during and after heavy rain when water
quality may be poor and more chlorine reacts with dirt in the water, too little chlorine
is added to kill germs in the water. (Chlorine will not kill Cryptosporidium.)
Action needed: Either an automatic chlorine dosing system, or a better monitoring
programme to check on the free available chlorine (FAC) level in the water, is needed
to improve the reliability of disinfection.

The people with responsibility for looking after the reticulation system are uncertain
about the right procedures for disinfecting the mains, if a repair is necessary. Without
the right training they may cause contamination of the water.
Action needed: Get training for the people who have to make the repairs, so that they
know how to disinfect the mains, and what other hygienic practices they need to
follow.
These problems show that in the Huia Flat supply, two of the four key barriers protecting a
water supply (protection of the source water and particle removal) are missing, and that there
are times when problems may arise with the remaining two barriers.
The priority rankings that should be given to the actions noted above are listed in the
following Improvements Schedule. The actual timetabling is given in the Action Timetable.
Improvements schedule
1
2
3
4
5
6
7
8
9
Equipment
and any
installation
costs
(estimated)
Overall
priority for
making the
improvement
Comments
Costs
#
Improvement
needed
Level of risk
(see Risk
Information
Table)
Ref W2
Version 1, January 2014
Health
Can the
priority improvement be
made within the
next few weeks
Staff
time
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
21
1
Improve the
security of the
well-head
High
3
No
Moderate
$1200
4
Cost – sealing the well and building a
shed around it, using local equipment
and labour where possible.
2
Install a cartridge
filter
High
1
No
Moderate
$5500
3
Cost – cartridge filtration unit to meet
the requirements of DWSNZ, and a
prefilter to protect the fine filter,
installation and training of staff.
Replacement cartridge costs must be
included in operational costs once
these are needed.
3
Improve the
monitoring of the
chlorine residual
High
2
Yes
Low
$20
1
Cost – additional chlorine testing
tablets needed for the increased
monitoring.
Water Supply Committee considered
that an automatic chlorine dose
controller is too expensive at this time.
Instead, better control over chlorine
dosing will be achieved by improved
FAC monitoring.
Need to seek some advice, perhaps
from the council’s EHO, about the best
way of improving the chlorine
monitoring.
Train staff who
carry out mains
repairs in the
right way to avoid
contaminating
the water during
the work.
4
High
4
Yes
Low –
moderate
$0
2
Cost – only necessary to find time for
staff to travel into town to talk with the
local authority for advice on the correct
procedures for mains repairs.
Notes on the Improvements Schedule:
Column 3: These are the levels of risk given in the Risk Information Table for the event each improvement is
supposed to stop happening. The Ministry of Health’s “How to Prepare and Develop Water Safety Plans for DrinkingWater Supplies” booklet suggests listing these levels as a starting point for deciding on the health importance of
each improvement. In this case, all the events have a “high” estimated level of risk, which doesn’t help in giving the
improvements a health priority. Instead, compare the four improvements as done for Huia Flat under the “Column
4” heading below.
Column 4: In this column you give each Improvement a ranking (from 1 to 4 in this case) based on its health
importance only. Do not worry about the cost or whether you have the resources when deciding on the health
priority. The reasons for the rankings given to the Huia Flat supply improvements are as follows:

Stopping contamination of the water after treatment is very important, but in Huia Flat mains repairs are rarely
needed (at present). For this reason Improvement #4 is ranked “4” for health priority.

Improvement #1 will certainly reduce the likelihood of contaminants getting into the well, but there will still be the
possibility of some contamination getting into the raw water because of the thin soil cover, the porous nature of
the ground and the number of cows grazing in the area. Fixing the problems with the treatment system is
therefore considered to provide a better barrier to contaminants, and is therefore more important for health.
Improvement #1 is ranked “3”.

The two improvements to the treatment processes are both important for public health. However, the loss of a
satisfactory level of chlorine happens only during heavy rain, while the inability to take out particles, particularly
the larger germs, is always a possible problem that may lead to people getting sick. Improvement #2 is therefore
given “1” ranking and Improvement #3, “2” ranking.
Making decisions about the health importance of improvements can be difficult. If you have a long list of
improvements, sorting them into three categories of say: “high importance”, “medium importance” and “low
importance” provides a good start. Sorting out which improvements fall into each of these groups is probably more
important than working out the detailed order within each group. If you are having difficulty, go to your local city or
district council and get advice from an environmental health officer.
Column 5: One of the things you need to think about when deciding the order in which you should make
improvements, is how easily each improvement can be made. Work on improvements that can be made easily and
quickly should be given a high priority, even if they do not have a high health priority. This column lets you note
down whether any of the improvements can be made quickly.
Column 6: Columns 6 and 7 collect estimates of costs for each improvement. How well you can fit the improvement
into your budget is likely to affect the overall priority you are able to give it. In Column 6 you can record the amount
of staff time you think this work is likely to take up. In the Huia Flat example, two of the improvements will probably
take up only a few hours of time. Part of the time required in installing the filtration system will be the need for the
company providing the equipment to train the operator in its use. There is no need to know the exact time required,
so long as it is possible to work out a rough level that will help in the final ranking of the improvements.
Column 7: Some idea of the cost of each improvement (including the equipment and installation) is needed here.
Estimates in dollars will be helpful in deciding which improvements can be made within your budget.
22
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
Ref W2
Version 1, January 2014
Column 8: This column contains the order in which you think the improvements should/can be made after taking
account of all the other factors in the Improvements Schedule. The following process was used to reach the priorities
given in Column 8:

Are there any improvements with high health priority that can be made easily and at little cost?
Yes: #3 – give it top priority.

Are there any other improvements that can be made easily and at little cost?
Yes: #4 – give it priority 2.

Are there other improvements of high health priority?
Yes: #2 – this improvement cannot be made immediately because of its cost, give it priority 3.

Are there any remaining improvements?
Yes: #1 – give it priority 4. If other improvements had been identified, ranking would have been based on the
benefit for health to be gained from it compared with the cost of resources (money and staff time etc).
In situations where there is an Improvement of very high health importance needed, it should be given a high priority
and carried out as soon as possible, even if its cost is high. In the Huia Flat example, Improvement #2 is considered
to be highest health importance, but it cannot be afforded immediately. Although Improvement #1 can be afforded
first, doing it first would delay being able to afford Improvement #2. This is why Improvement #2 is given the higher
overall ranking. Note also that although Improvement #2 is ranked “3”, the two Improvements #3 and #4 can be
made quickly and for little expense, so they have no impact on how soon the most important health improvement
can be made.
Column 9: This column can be used to provide notes about improvements where needed.
Ref W2
Version 1, January 2014
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
23
Action timetable
Action
Completion
date
Person responsible
1
Meet with everybody who has a responsibility in
this timetable to discuss and agree on what has to
be done, and ensure they have a copy of the
Action Timetable.
31 Jan 2002
Water Supply
Committee Secretary
2
Arrange for a visit to a local EHO or HPO to get
advice on how best to improve the FAC
monitoring.
4 Feb 2002
Water Supply
Committee Secretary
3
Arrange for a visit to the local authority by those
who look after the maintenance of the reticulation
system to discuss good practices for making
repairs.
4 Feb 2002
Water Supply
Committee Secretary
4
Visit the EHO/HPO contacted (Action 2) for a
discussion and advice on FAC monitoring.
13 Feb 2002
Supply operator
(Mr Waterbury)
5
Draw up a new monitoring plan and start using it.
14 Feb 2002
Supply operator
(Mr Waterbury)
6
Visit the local authority to discuss reticulation
repair procedures (Action 4).
18 Feb 2002
Reticulation
maintenance person
(Mr Seaforth)
7
Prepare a brief manual for the Huia Flat water
supply as guidance for those having to make
reticulation repairs.
Mar 2002
Reticulation
maintenance person
(Mr Seaforth)
8
Discuss needs, and obtain quotes, from suppliers
of cartridge filtration systems. There is to be a
requirement that the unit will be capable of
meeting compliance criteria for DWSNZ.
Jul 2003
Water Supply
Committee
Chairperson
9
Select the favoured supplier.
Sep 2003
Water Supply
Committee
10
Filtration supplier installs new cartridge filtration
system, and ensures that at least two people from
the Water Supply Committee, including the
operator, are trained in its operation.
Oct 2003
Supply operator
(Mr Waterbury)
11
Draw up plans for a well-head seal and pad, and
have them checked by a local EHO or HPO.
Feb 2004
Supply operator
(Mr Waterbury)
12
Arrange for a community workgroup to prepare
the well-head for laying the concrete seal and
pad. Order the necessary supplies.
Mar 2004
Water Supply
Committee secretary
13
Lay concrete well-head seal and pad, and erect
fence.
Mar 2004
Water Supply
Committee
Chairperson
Improvement
completed
3
4
2
1
Notes on the Action Timetable:

Actions in the timetable should include the smaller steps needed to complete each improvement. This helps all
those involved in their planning. (More detail may be required than given in the example.)

It is important that once the person with overall responsibility for the water supply has drawn up a draft timetable,
there is a meeting to discuss what has to be done, how it should be done, and to check that those people who
have been given responsibilities are prepared to accept them.

The last column in the table is included to help identify when each of the improvements contained in the
Improvements Schedule has been completed.

All improvements from the Improvements Schedule should be included in the table, even if it is not possible to
fix a completion date. This helps to make sure that these improvements are not overlooked.
24
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
Ref W2
Version 1, January 2014
Regular Checks and Maintenance
Schedules
The following table summarises checks that are carried out on the Huia Flat Community
water supply, how often they need to be made and who is responsible for them.
Regular checks
Check
1
Levels of germs
(E. coli)
Details

Take samples directly after
treatment, and from the
reticulation system.

Check the Drinking-Water
Standards for New Zealand for
details, or get advice from an
HPO if needed.
How often
Responsibility
Monthly
Water Supply
Committee
Chairperson
2
Well–head

Signs of damage (intentional
and unintentional).
Weekly
Supply operator
3
Free available
chlorine
concentration

Make measurement in water
entering the storage reservoir.
Refer to revised
monitoring plan for water
directly after chlorination
(when developed).
Supply operator

Make measurement in the
farthest point of the distribution
system from the treatment
plant.
Monthly in distribution
system.
4
Chlorine dosing
solution

Check level or solution, and
from experience of how
quickly it is used, check
whether a replacement needs
to be ordered.
Judge by experience. It
will depend on how
quickly a chlorine
container is usually used
up, and how long ago
the container in use was
started.
Supply operator
5
Quality of
chlorine solution

Check certificate of analysis.
With every new batch of
chlorine.
Supply operator
6
Chlorine storage

Chlorine solution should be
kept dark and as cool as
possible.
With every new batch of
chlorine.
Supply operator
7
Dosing pump

Operation of the pump.
Tubes carrying chlorine
solution for blockage.

Weekly unless low
chlorine readings
indicate there is a
problem.
Supply operator

Reading on flowmeter.

Important that the pH of the
water does not get too high.
At high pH chlorine becomes a
poorer disinfectant.
Monthly. (If large drifts
in pH are found, checks
may have to be more
frequent.)
Supply operator
8
pH
Ref W2
Version 1, January 2014
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
25
Check
9
Tank (external
and internal)
Details

Mesh and grills displaced or
missing so animals can get
into the tank.

Signs of vandalism.

Build up of sediment and clean
out if needed.

Water levels (warning of water
shortage).
How often
Responsibility
Monthly
Supply operator
Annually (sediment)
10
Appearance of
water

Cloudy or discoloured.
Daily
Whole community
11
Water pressure

Lower pressure than usual at
consumers’ taps, or
Daily
Whole community

Pressure meters in the
reticulation (if available).

Test for germs.

Check on levels of chlorine
after chlorinated water has
been standing in the repaired
section of line.

Inspection by qualified person
(or work done by qualified
person).
12
Mains repairs
13
Connections to
reticulation
system
14
New situations
that might lead
to water being
sucked back into
the drinkingwater supply
(backflow)
15
Exposed parts of
the reticulation
system

Signs of damage (intentional
and unintentional).
Reticulation
maintenance
person (for meter)
With repairs
Reticulation
maintenance
person
At the time connection is
made.
Reticulation
maintenance
person
Annual
Reticulation
maintenance
person
Weekly
Reticulation
maintenance
person
A number of the daily checks noted in the table can be made by anybody in the community
or on the Water Supply Committee, during their movements around the area. Any concerns
should be passed on to the Committee, supply operator or reticulation maintenance person.
A log book is to be kept of all checks that are made (not necessary for the daily checks). This
log should record any problems that are found (including those found during daily checks),
and what corrective actions were taken.
The following table summarises maintenance schedules that need to be followed.
Maintenance schedules
Schedule
Responsibility
1
Bore pump – follow manufacturer’s instructions
Supply operator
2
Chlorine dosing pump – follow manufacturer’s instructions
Supply operator
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
Ref W2
Version 1, January 2014
26
A log book is to be kept to record any maintenance undertaken, including any work carried
out on the reticulation system by a properly qualified plumber. The manufacturer’s
maintenance instructions must be filed so that they can be easily found.
Notes on checks and maintenance schedules

These checks and schedules are obtained from the Risk Information Table.

Summary of them in one section makes it clear to those using the plan, and those assessing the plan, which
checks and maintenance work need to be undertaken.
Ref W2
Version 1, January 2014
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
27
Contingency Plans
The following set of Contingency Plans are guides to what to do in case an event occurs
despite preventive measures or corrective actions to stop it.
If there are difficulties in deciding how serious the event is, contact the local Medical Officer
of Health (MOH).
Event – Large amounts of contamination enter the groundwater or well
Indicators:
Required actions:

Report of chemical spill in an area where chemicals may get
into the groundwater you use.

Your consumers complain of discoloured, or bad tasting or
smelling water coming from their taps.

High levels of germs or chemicals are found in samples you
have taken of your water supply.

Many people in the community complain of illness which
may be linked to water quality.

Stop drawing water from the well, and alert emergency
services if it is a chemical spill.

Tell the MOH about what has happened and discuss. Warn
consumers not to draw water until further notice, and find
another source of water until water quality returns to normal.

Identify what is causing the contamination, and decide
whether the problem is likely be short term or last for a long
time.

If problem is short-term:
–
drain and flush the affected part of the reticulation
network. Your may have to fill the reticulation
network with high levels of chlorine if high levels of
germs were in the water. (Check with the regional
council about the best way to dispose of the high
chlorine water)
–
28
sample for the chemical of concern or germs to find
out when the water can be used again. Let consumers
know when the supply is safe to use, and tell them to
flush their taps until good quality water is again
flowing.
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
Ref W2
Version 1, January 2014

Responsibility:
If problem is likely to be long-lasting:
–
look for a new source of water or consider more
treatment
–
record cause of the system failure and what you did to
correct the problem
–
modify water safety plan if necessary.
The Water Supply Committee chairperson must ensure that the
source is protected; the organisation/person responsible for any spill
must be responsible for all action to address the damage caused by
the spill.
Event – Earthquake
Indicators:
Required actions:
Responsibility:

An earthquake may cause damage to the source, treatment
plant or reticulation network. The water supply may be shut
down as a result.

Destroyed well-head, chlorination shed or reservoir.

Geysers of water from breaks in the reticulation network
pipes.

Contact the Ministry of Civil Defence in the event of an
earthquake emergency. (Keep a list of the contact details for
the nearest Ministry and Earthquake Commission offices.)

Check your well-head, chlorination system, storage tank, and
the reticulation network.

If any part of the supply is damaged so that water cannot be
distributed or the quality is unacceptable, use an alternative
supply. This should include checks on the quality of the
source water, which may have changed because of the
earthquake. Provide another source of water until water of
acceptable quality can again be supplied.

Tell MOH about the situation.

Record what has happened and what you have done to
overcome any problems.

Modify water safety plan if necessary.
Water supply committee chairperson.
Ref W2
Version 1, January 2014
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
29
Event – Water shortage
Indicators:
Required actions:
Responsibility:

Low groundwater table.

Water usage much higher than usual.

Drop in water pressure.

If the water table has dropped so low that no water, or very
little, can be pumped out, use another source of water until
the table has again risen and can be used. (If you get a tanker
to supply water, make sure you know what it was used for
before, so that you do not get contaminated water.)

Restrict water use.

If water shortages occur often, plan to find an additional
source of water.

Record what has happened and what you have done to
overcome the problems.

Modify water safety plan if necessary.
Water supply committee chairperson.
Event – Chlorine concentration is lower than minimum acceptable level
Indicators:
Required actions:
Responsibility:
30

You cannot detect chlorine in the water following
chlorination.

In 100 ml samples of water taken after storage tank, E. coli or
coliforms (germs) are continually detectable, or are present at
levels of more than 10 per 100 mL.

People in the community complain of illness which may be
linked to water quality.

Follow the actions given in Figure 3.2 of the DWSNZ:2000.

Find out why the chlorine concentration is too low, and fix
the problem.

Record cause of system failure and steps taken to correct.

Record what went wrong and why, and what you have done
to overcome the problems.

Modify your water safety plan if necessary.
Water supply committee chairperson.
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
Ref W2
Version 1, January 2014
Event – Chlorine concentration is very much higher than maximum acceptable value
Indicators:
Required actions:
Responsibility:

A major spillage or overdose of chlorine into the water.

You cannot get a pink colour with the test kit (assumes a DPD
test kit) despite high chlorine dose rates. (NB: This shows
chlorine levels well above the maximum acceptable value –
very high chlorine levels bleach the pink colour that chlorine
normally produces in the test.)

Water smells strongly of chlorine.

Many people in the community complain of the taste and small
of the water and of getting sick.

Close down the chlorinator. Find another source of potable
water until the quality of water from the supply is again of
good quality.

Tell the MOH what has happened.

Find out what caused the chlorine overdose, and fix the
problem.

Dump the water in the storage tank, or add chemicals to
destroy the chlorine if the water cannot be dumped.

Flush the reticulation network if levels of chlorine are high
there. Make check measurements to see when the levels have
returned to normal.

Warn consumers to thoroughly flush their taps before drawing
water for use (if they are likely to have been affected).

Record what went wrong and why, and what you have done to
overcome the problems.

Modify your water safety plan if necessary.
Water supply committee chairperson.
Ref W2
Version 1, January 2014
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
31
Event – Germs detected in water in the storage tank
Indicators:
Required actions:
Responsibility:

You cannot detect chlorine in the water in the tank.

In 100 ml samples of water taken from the tank, E. coli or
coliforms (germs) are continually detectable, or are present at
levels of more than 10 per 100 mL.

People in the community complain of illness which may be
linked to water quality.

You know that the water in the tank has been sabotaged or
there has been vandalism.

Follow the actions given in Figure 3.3 of the DWSNZ:2000.
Discuss the situation with the MOH and decide whether the
water should be dumped if high levels of germs have been in
the water, even if there is not sign of them in the last sample
tested.

Find out why the chlorine concentration is too low, and fix the
problem.

Record cause of system failure and steps taken to correct.

Record what went wrong and why, and what you have done to
overcome the problems.

Modify your water safety plan if necessary.
Water supply committee chairperson.
Event – Contamination enters the reticulation network
Indicators:
Required actions:
Responsibility:
32

You are unable to measure a chlorine residual in the
reticulation network, when you usually can.

The water is cloudy, or the cloudiness is changeable.

In 100 ml samples of water from the reticulation network,
E. coli (germ) is continually found or is present at levels more
than 10 per 100 mL.

People in the community complain of the taste and smell of the
water and of getting sick.

Follow the actions given in Figure 3.3 of the DWSNZ:2000.

Find out the cause of the contamination, and fix the problem.

Record what went wrong and why, and what you have done to
overcome the problems.

Modify your water safety plan if necessary.
Water supply committee chairperson.
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
Ref W2
Version 1, January 2014
Water Safety Plan Performance
Assessment
Each year this plan is to be checked to make sure it is doing its job properly. This is done
by:

checking whether the water quality has shown compliance with the Drinking-Water
Standards for New Zealand

seeing whether any problems have been found during the regular checks and
maintenance schedules (these should be easily done by checking the log book that is
kept).
If germs have been found in the water, or the checks have shown there to be problems, the
plan needs to be changed to show:

any new causes that have been found

new preventive measures for existing causes, or to deal with any new causes

any changes to how often checks should be made (experience may show the need for
changes)

any new improvements needed.
Each year the Improvements Schedule and Action Timetable will need to be updated, because
a number of improvements may have been made, and new ones may need to be added.
If there have been any changes to the supply, such as new treatment, changes to the source,
new events may have to be added to the Risk Information Table.
If a Contingency Plan has been used, any improvements to the Contingency Plan that should
be made.
The Water Supply Committee chairperson has responsibility for reviewing how well the plan
is working and making the changes necessary.
Ref W2
Version 1, January 2014
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
33
Reporting
The Water Supply Committee chairperson has responsibility for preparing a brief annual
report on the water supply and the risk management of the supply to the Committee, any of
the community who may have an interest, and the District Health Board, should they request
it. This report should include the following information:

Has the supply complied with the Drinking-Water Standards for New Zealand (shown
by the germ monitoring, and any chemical monitoring required by the Ministry of
Health)?

If it has not complied, what was the reason and what is being done to overcome the
problem?

How well is the timetable for making necessary improvements to the water supply
being followed?
The District Health Board will also require a record of monitoring results to make sure the
supply is complying with the Drinking-Water Standards for New Zealand.
34
Example Water Safety Plan:
Small Chlorinated Groundwater Supply
Ref W2
Version 1, January 2014