Water Safety Plan
Guide
Worked Example of a Water Safety
Plan for a Small Supply Using
Rainwater
Version 1, Ref W1
January 2014
Citation: Ministry of Health. 2014. Water Safety Plan Guide: Worked
Example of a Water Safety Plan for a Small Supply Using Rainwater,
Version 1, ref W2. Wellington: Ministry of Health.
Published in January 2014
by the Ministry of Health
PO Box 5013, Wellington, New Zealand
ISBN: 978-0-478-42772-1 (print)
ISBN: 978-0-478-42773-8 (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 Rainwater, 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 Greendell School
3
Barriers to Contamination
4
Risk Information Table
5
Improvements
17
Regular Checks and Maintenance Schedules
22
Contingency Plans
24
Water Safety Plan Performance Assessment
27
Reporting
28
Ref W1
Version 1, January 2014
Water Safety Plan Guide:
Small Rainwater 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 fewer then 500
people) prepare their water safety plans. Notes 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 chart 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 what 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.
–
–


Make a check list of the four “barriers to contamination” your supply has, so
that any that are missing can be identified.
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.
–
Prepare contingency plans that might be needed for your supply.
Prepare a summary of regular checks and maintenance that needs to be carried
out.
Plan evaluation and communication
–
Prepare a list of instructions for reviewing the performance of the plan.
–
Prepare a list of instructions for reporting.
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Version 1, January 2014
Water Safety Plan Guide:
Small Rainwater Supply
1
Scenario
This example uses the imaginary Greendell School, which is a small cluster of buildings on
the edge of Greendell village (also imaginery). The village is situated in a valley, about 20km
from an active volcano. Native bush surrounds the village and many trees grow in the school
grounds and near the buildings. Rainwater is collected from the roofs of the school buildings
to provide a source of water. There is a high rainfall in the area and as a result the school
never experiences water shortages.
The rainwater from the roofs is collected in three concrete storage tanks. From there it is
pumped to a header tank on the hillside to provide gravity feed for the supply. After the
header tank, the water passes through a cartridge filter, and is then disinfected by a ultraviolet disinfection system before being reticulated to the school buildings.
Greendale Rural School has four teachers, and a part-time caretaker who also looks after the
water supply.
2
Water Safety Plan Guide:
Small Rainwater Supply
Ref W1
Version 1, January 2014
Water Safety Plan for Greendell
School
Diagram of the water supply
Collection of water
from roof
Water storage
tanks
Header
tank
Pump
Cartridge
filtration
UV
disinfection
Reticulation
pipework around
the school buildings
The individual Guides used in the preparation of this Plan were:

S1.2 Roof catchments

P6.3 Cartridge filtration

P7.4 Ultra-violet irradiation

P10 Pump operation

D2.3 Operation (reticulation network)

D2.4 Backflow prevention

G1 Staff training

G2 Monitoring
Ref W1
Version 1, January 2014
Water Safety Plan Guide:
Small Rainwater Supply
3
Barriers to Contamination
The barriers to contamination in place in the Greendell School supply, and the concerns about
how well they work, are summarised in the following table:
Barriers to:
Comment
Stop contamination of raw water
There are a number of ways in which the raw water could be
contaminated. The improvements needed to stop contamination are
listed.
Remove particles from the water
Cartridge filter
Kill germs
Ultra-violet disinfection – the UV unit is old and does not have a light
sensor. This is listed in the needed improvements.
Prevent recontamination after
treatment
The important steps to stopping contamination after treatment have been
or are being taken:

The water supply is totally enclosed after treatment and not open to
external contamination.

There are no places where water could be sucked back into the
supply.

A qualified plumber is always called when work on the water supply
is needed.
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
Water Safety Plan Guide:
Small Rainwater Supply
Ref W1
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 treatment

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.
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.
Ref W1
Version 1, January 2014
Water Safety Plan Guide:
Small Rainwater Supply
5
Abbreviations: DWSNZ – Drinking-Water Standards for New Zealand; MAV – Maximum acceptable value – see
DWSNZ:2000; Council – regional/district council or unitary authority.
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
The roof catchment and water storage
Event: ANIMAL DROPPINGS AND CHEMICAL CONTAMINANTS CARRIED ONTO ROOF OR INTO
GUTTERING
Possible hazards: Germs, pesticides, other chemical contaminants that may be airborne.
Level of risk: High1
C1.1.1

Cut back trees.
Overgrown trees:

Clean out guttering.
–

Put wire or plastic
mesh over the top of

the downpipe, or over
the whole guttering, to
stop leaves getting
into the tank.
may allow
animals and
birds to
contaminate
the roof
–
water dripping
off branches
onto the roof
may carry
contaminants
–
dead animals
may fall into
the guttering.
C1.1.2
Droppings from
birds or animals
on roof or in
guttering.


Keep roof and

guttering clean and
use first flush diverter.

String wire along the
ridgeline to stop birds
roosting.

Check tree
growth at
least
annually.

Overgrown
trees.

Dirty guttering.
Check
guttering at
least
annually.
Quarterly
inspection of
roof and
guttering for
droppings.

Droppings on
roof or in
guttering.

Cut back trees.

Disconnect
downpipe from
tank and clean
guttering.

Disinfect the
water.

Disconnect
downpipe from
tank and clean
roof and guttering.

Disinfect the
water.
Take actions to avoid
attracting birds, eg.
don’t feed them and
tidy away rubbish.
1
The germs create a ‘high’ risk, not the chemicals.
6
Water Safety Plan Guide:
Small Rainwater Supply
Ref W1
Version 1, January 2014
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
Event: ANIMAL DROPPINGS AND CHEMICAL CONTAMINANTS CARRIED ONTO ROOF OR INTO
GUTTERING – cont’d
C1.1.3

Chemical
contaminants
from the air
(including aerial
spraying) settle
on roof.
C1.1.4
Chemical
contamination by
sprays used to
protect roof
timbers, or proof
against spiders.
C1.1.5


Consider using a
water source less
affected by air
pollution.

After possible
contamination
disconnect downpipe
before the next rain
(or use a first-flush
diverter).

Check your chimney
is long enough that
material from the fire
will not settle on the
roof.

Tell the contractor

that the roof is used to
collect drinking-water,
and that there must
be no overspraying.

Get a guarantee from
the contractor that
persistent
organochlorine
pesticides2 will not be
used.

Find out
which
chemical
sprays are in
use nearby.

Noticeable taste 
in the water.

Algal growths in
water tank if
fertilisers have

contaminated
the roof.
Appearance
of roof.


List of
pesticides
used by
contractors.
If you are
worried that
spray has got
onto the roof,
sample for
pesticides in
the water.

Use first-flush diverter
or disconnect
downpipe, before first
rain after treatment of
the roof.

Make it as difficult as
possible for people to
get onto the roof, eg
lock away ladders.

Check the
roof for
unexpected
objects.

Check the roof
regularly for signs of
intentional
contamination (eg,
bags of chemicals).

Check the
area around
the building
for things that
may make
getting onto
the roof
easier.
Vandalism/
sabotage.
2
Ask the council for
help to reduce air
pollution in the area
(using discharge
consents). Keeping
notes on
contamination
incidents may help.

Visible deposits
of ash/soot on
the roof.
Use of
persistent
organochlorine
insecticides2 by
contractor.

Overspraying
happened.

Water contains
pesticides at
concentrations
more than 50%
of their MAV.

Signs that
someone has
got onto the
roof without
permission.
Ask for council
help to reduce
sources of air
pollution.
Use a new source
unaffected by air
pollution (eg,
groundwater).

Install a first-flush
diverter.

Lengthen
chimney.

Use different
contractor.

Thoroughly wash
down the roof –
disconnect the
downpipe.

Use an alternative
water source until
decontamination
is complete.

Remove things
that might help
people get onto
the roof.

Remove
contaminants
from the roof,
disconnect
downpipe and
wash down.
This chemical group includes: aldrin, dieldrin, lindane chlordane, DDT, DDE, so check whether any of these
chemicals are in the product being used by the contractor.
Ref W1
Version 1, January 2014
Water Safety Plan Guide:
Small Rainwater Supply
7
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action is
needed
What to check
Event: MATERIALS DISSOLVED FROM THE ROOF, FLASHING, GUTTERING OR DOWNPIPES BY
RAINWATER
Possible hazards: Heavy metals (lead, copper, chromium, cadmium).
Level of risk: Moderate

C1.2.1
Roof materials
containing lead,
and guttering
made from

metals that can
corrode.

Use lead-free
materials on the
roof (paints,
flashings, nails).

Keep roof surface in 
good repair.
Use plastic
guttering.

Check condition 
of roof surface
at least
annually.
Building
materials, or
paint, used on
the roof.
Test for heavy
metals in roof
paint.3
Roof surface in poor 
condition – needs
repainting or
replacing.

Leaded paint test
on roof paint is
positive.

Lead flashing used
on the roof.

Cases of lead (or
other heavy metal)
poisoning, but be
aware that such
cases may have
other causes.
Replace
materials that
contain heavy
metals.

Repaint roof, or
replace roof.

Replace
guttering.
Event: CONTAMINATION OF WATER WHILE IN THE STORAGE/HEADER TANK
Possible hazards: Germs.
Level of risk: High
C1.3.1

Animals getting
into storage
tank.
Ensure the tank is
covered.

Put mesh on vents,
overflow, etc.

Check inside of tank
monthly.
C1.3.2

Remove vegetation
near tanks

Put a slippery metal
band around
wooden tanks to
prevent animal
access from ground
level.

Clean the tank each 
year.
Accumulation of
sediment in

storage tank.

C1.3.3
Vandalism/
sabotage.
3
8

Monthly tank
inspection.
Monthly tank
inspection.
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).
Take steps to stop
people getting
access to the tank
(fences, locked
hatches).

Regular
inspection of
tanks for signs
of someone
getting into the
tank.

Dead animals
found in tank.

Mesh/grills
disturbed by
animals to get into
the tank.


Unpleasant taste
and odour.

Water cloudy.

Dead animals
found in tank.

Mesh/grills
disturbed by

animals to get into
the tank.

Unpleasant taste
and odour.

Water cloudy.

Signs that
someone has got
into the tank
without
permission.

Remove animal
remains, and
disinfect the water
before use (eg,
UV disinfection).
Replace or
provide mesh
where necessary.

Prepare a
timetable for
checking the tank.

Start inspection
and cleaning
programme.

Install a second
tank.
Fence tank, or
provide lockable
hatches.
Seek help from a health protection officer from the District Health Board. They should have a small kit that will
allow a quick test of the paint.
Water Safety Plan Guide:
Small Rainwater Supply
Ref W1
Version 1, January 2014
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action is
needed
What to check
Event: NOT ENOUGH WATER
Possible hazards: Hazards associated with poor hygiene.
Level of risk: High
C1.4.1

Too little rainfall
as well as too

little storage,
high use of
water, or a leak
in tank or

guttering.
C1.4.2
Water level in
tank.

Water supply often
runs out.
Make sure guttering is 
strong enough for
wind and snowfall
conditions.
Rate of water
use.

Water level is low.

Signs of water
leaking from tank.
Check tank and
guttering monthly for
leaks.

Stop unnecessary use
of water.

Do preventive
maintenance on
pump:
– daily visual
inspections
– lubrication
– seal replacement
– leaks repaired
– corroded
components
replaced
– annual ammeter
tests.
Mechanical
failure of pump
(header tank
short of water).
C1.4.3

Make sure tank is big
enough.

Pump
maintenance
log.

Frequent pump
breakdowns.

Pump maintenance
not being done.

Planned maintenance
programme for
replacement of pump
parts (follow per
manufacturer’s
recommendations).

Install an alarm that
warns that the power
has failed.

Alarm.

Alarm is triggered.



Electricity
supply.
No electricity
reaching the pump.
Install a stand-by
generator.

Water flow.


Regularly maintain
the power supply (if
you have a diesel
generator, for
example).
No water flow to
header tank when
pump should be
operating.
Power failure to
pump.
Ref W1
Version 1, January 2014

Get new tank.

Find a new or
additional
source of water.

Repair tank
and/or
guttering.

Take steps to
save water.

Revise, or put in
place a pump
maintenance
schedule.

Make
arrangements
to get a more
reliable power
supply.
Water Safety Plan Guide:
Small Rainwater Supply
9
Causes
Preventive measures
Checking preventive measures
What to check
Corrective action
Signs that action is
needed
Cartridge filtration
Event: FILTER NOT REMOVING PARTICLES DOWN TO 2 µm IN SIZE
Possible hazards: Large germs (Giardia and Cryptosporidium not removed).
Level of risk: High4
C1.5.1

Use filters that are
certified to remove
particles down to
2 m in size.

Make sure filter

cartridge is
compatible with the
filter housing and note
the type of filter used.
Wrong type of
cartridge filter.

C1.5.2
Damage to the
seal between
the cartridge
and filter
housing.


C1.5.3
Cartridge not
properly seated
in the mounting.
Check the condition of 
the filter housing and
the cartridge seal

when changing filters.
Make sure the person
replacing the

cartridges knows the
correct way to do it.
Make sure the
cartridge is fitted the
correct way round
(some only work one
way).

Make sure base of
filter housing is wiped
clean before reseating
filter cartridge.

Make sure cover is
replaced properly.

Check, directly after
re-seating it, that the
filter is removing
particles. (Checks
are described in
Sections 3.2.3.1 and
11 of DWSNZ: 2000).


National or
international
certificate of
filter’s
capabilities.5

Cloudiness in the
water following
filtration.

Change to a
different type of
filter.

Customer
complaints.

Record of filter
types used.

Cases of
diarrhoea in
people drinking
the water.
Keep list of
filters that
match the
housing in use.

Wrong filter type
used.

Cloudiness in the
water following
filtration.


Customer
complaints.

Decide whether
the cartridge or
housing is
damaged, and
replace
damaged unit.
Cases of
diarrhoea in
people drinking
the water.


Train staff in
replacing
cartridges if
necessary.
Frequent damage

to seal.
The state of the
filter seal.
Filter
maintenance
log.
Appearance of
the water.

Results from

particle removal
checks.

Appearance of
the water.
Cloudiness in the
water following
filtration.


Filter unable to

remove more than
99.9% of particles
greater than 2 µm
in size entering it.

Customer
complaints.

Cases of
diarrhoea in
people drinking
the water.

Frequent incorrect
seating of filter.
Read filter
manufacturer’s
instructions.
Read filter
manufacturer’s
instructions.
Train staff in
replacing
cartridges if
necessary.
Make sure the person
replacing the
cartridges knows the
correct way to do it.
4
The level of risk will depend on the type, and effectiveness, of any disinfection after cartridge filtration.
5
For example, certification under NSF Standard 53 or AS/NZ 4348:1995.
10
Water Safety Plan Guide:
Small Rainwater Supply
Ref W1
Version 1, January 2014
Preventive
measures
Causes
Checking preventive measures
Corrective action
Signs that action is
needed
What to check
Event: FILTER NOT REMOVING PARTICLES DOWN TO 2 m IN SIZE – cont’d
C1.5.4

Cartridge
failure.

C1.5.5

Contamination
of filter housing
when changing
the cartridge.
C1.5.6
Flow too high
for cartridge
design.
6
Regularly
replace filter
cartridges, and
wash pre-filters.
Note the date
and what is
done.
Before buying
new cartridges
check they have
certificates
showing they
meet
specifications.
Disinfect filter
housing when
installing the
cartridge, and
flush to waste to
remove residual
disinfectant.

Make sure the
person replacing
the cartridges
knows the correct
way to do it to
avoid
contamination.

Keep flow rate
less than the
maximum the
filter can handle.

Flow rate.

Difference
between the
pressure before
the filter and
after the filter.
(Sudden
changes in flow
or the pressure
difference may
indicate filter or
pre-filter failure.)



Performance
certificates.
Test the water
leaving the filter
for the
disinfectant.6
Flow rate.

Pressure
difference is lower
than usual, or flow
is higher than
usual.

Cloudiness in the
water following
filtration.

Customer
complaints.

Cases of diarrhoea

in people drinking
the water.

Records not kept.

Disinfectant
concentration not
reduced to an
acceptable level.

Customer
complaints.

Cases of diarrhoea
in people drinking
the water.

Flow too high.

Cloudiness in the
water following
filtration.

Customer
complaints.

Cases of diarrhoea
in people drinking
the water.

Wash the filter
cartridge and
flush to waste
until checks
show that
particle
removal is
again effective.

Get another
batch of
cartridges.
Consider
changing filter
supplier.

Continue
flushing until the
disinfectant
cannot be
detected.

Train staff if
necessary.

Reduce flow to
within
specifications.
If household bleach (chlorine) is used to disinfect the filter housing, chlorine test tablets from a swimming pool
test kit can be used for this. They turn pink when there is chlorine in the water. Use 1 tablet in 10ml of water; a
slight pink colour indicates that the chlorine concentration is acceptable.
Ref W1
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Water Safety Plan Guide:
Small Rainwater Supply
11
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action is
needed
What to check
Event: GROWTH OF GERMS IN THE FILTER
Possible hazards: Germs (released from filter into treated water).
Level of risk: Moderate

C1.6.1
Filter used
in the wrong
situation or
beyond its
capacity.

Disinfect7 the water
before it goes
through activated
carbon cartridges
used to reduce
taste problems
(including those
claiming to stop the
growth of bacteria).

Record filter type
used.


Check
recommended

filter lifetime and
installation date of
cartridge in use.
Customer
complaints and
sickness.
Timetable for
replacing filters not
followed.

Avoid using a
carbon filter or
disinfect the water
before it gets to
the cartridge.

Disinfect water
after the filter.

Plan when filters
have to be
replaced, and
note replacement
dates.
Regularly replace
filter cartridges
(especially carbon
filters). Note the
replacement date.
UV disinfection
Event: UV DOSE TOO LOW
Possible hazards: Germs not killed.
Level of risk: High8

C1.7.1
Too little
UV light
passing
through the
water.

Regularly clean the
lamp sleeves and
light sensor lens.
Regularly replace
lamp and record the
date.

Make sure the light
sensor is on the
wall of the unit
farthest from the
lamp.

Lubricate the lamp
seal each time the
lamp is removed
(use water-based
lubricant).


Light intensity.

Alarm.

Signs of scale on
the lamp sleeve
and sensor lens.

Install an alarm that
warns when the
light intensity is too
low and shuts off
the water flow.

Alarm triggered
(light intensity too
low).

Clean lamp
sleeve and sensor
lens.

Water flow shut off.

Replace lamp.

Water inside lamp
sleeve (poor seal).

Move sensor so
that it measures
the light intensity
at the wall farthest
from the lamp, or
buy a unit with a
sensor in the right
place.

Lubricate lamp
seal with
approved
lubricant.

Add chlorine to
the storage tank
until satisfactory
water quality can
be restored, or
close the supply
down and arrange
for another supply
of water.
Records of lamp
replacement and 
when sleeves and
sensor were
cleaned.
No maintenance
records.
7
This is best done by adding chlorine to the holding tank. Use 1 teaspoon of bleach per 150L of water in the
tank. This gives a chlorine concentration of about 1 mg/L.
8
The quality of the source water and how well other treatment processes before the UV unit work will affect the
level of risk.
12
Water Safety Plan Guide:
Small Rainwater Supply
Ref W1
Version 1, January 2014
Preventive
measures
Causes
Checking preventive measures
What to check
Corrective action
Signs that action is
needed
Event: UV DOSE TOO LOW – cont’d
C1.7.2
Germs
exposed to
too little light
because
water flow is
too fast or
water is too
cold.
C1.7.3


Water flow
records.

Flows are low or
very changeable.

Replace or repair
the flow controller.

Minimummaximum
thermometer
readings of water
temperature.

Water
temperature is
low enough to
affect lamp
intensity.

Reduce the water
flow if the water
temperature is too
low.

Add chlorine to the
storage tank until
satisfactory water
quality can be
restored, or close
the supply down
and arrange for
another supply of
water.

Make arrangements
to get a more
reliable power
supply.

Add chlorine to the
storage tank until
satisfactory water
quality can be
restored, or close
the supply down
and arrange for
another supply of
water.

Follow
manufacturer’s
instructions about
adjusting water
flow if the water is
cold.

Install a filter
before the UV
disinfection unit
and make sure it
works (see
C1.5.1–C1.6.1).

See C1.5.1–C1.6.1.

Install an alarm
that warns that
the power has
failed, and shuts
off the water flow.

Alarm.

Alarm is triggered

Power to UV
disinfection unit.

No electricity
reaching the UV
unit.
Water
discoloured or
cloudy.
C1.7.4
Regularly check
and record water
flow to make sure
it meets
manufacturer’s
requirements.
Power supply
failure.

Install a stand-by
generator.

Regularly
maintain the
power supply (if
you have a diesel
generator, for
example).
Ref W1
Version 1, January 2014
Water Safety Plan Guide:
Small Rainwater Supply
13
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
Reticulation system
Event: CONTAMINATION ENTERS THE WATER AFTER TREATMENT
Possible hazards: Germs, chemicals.
Level of risk: High9

C1.8.1

Water
pressure at
taps.

Signs of leaks
found during
checks.

Start checking
the pipes
regularly.

Damage
checks.

Much more

water used than
expected.
Reduce the corrosiveness of
the water by placing marble
chips in the holding tank, for
example.


Rust-coloured
water, or water
with a bitter
“iron” taste.
Get advice on
how to make
the water less
corrosive.
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.

Get a properly qualified

person to make any repairs.
This person must:
– thoroughly wash their

hands before making the
repair
– clean and disinfect with
chlorine 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.
Breaks, leaks
or damage to
the pipes.

C1.8.2
Contaminants
enter the
water during
repairs to the
reticulation.
C1.8.3
Water pipes
are laid too
close to the
sewer.
9
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.

Record where the repair was
made, and who made it.

Use a properly qualified
contractor to lay pipes.

Appearance 
of the
water.
Repair
records.
See if you can
provide better
protection for
the pipes.

Employ a
registered
plumber to
make the
repairs OR
make sure the
person making
the repairs is
properly trained.

Get contractor
to relocate
pipes to make
sure there is
enough
separation.
Leaks appear
often.
Water is
discoloured, or
tastes or smells
bad.

People who
drink the water
get sick.

Repair is not
recorded.
Plans

showing
locations of
sewers and
drinkingwater pipes.

Plans show the
sewer and
drinking-water
systems run
close together.
The level of risk will be high if UV disinfection takes place a long way from the point of use, or water is stored
after treatment.
14
Water Safety Plan Guide:
Small Rainwater Supply
Ref W1
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
C1.8.4

Illegal crossconnection to
the water
supply.
C1.8.5

Contaminants
are sucked
into the
reticulation
(“backflow”).

Make sure only properly

qualified people make
connections to the supply.
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
installed:
– backflow-prevention
device
– double check valve
– air gap.
Inspection
of work.
Check the
supply for
places
where
backflow
prevention
is needed.

Cross-connections
found.


Water is
discoloured, or
tastes or smells
bad.
Employ a
registered
plumber to
make
connections OR
make sure the
person making
the repairs is
properly trained.

People who drink
the water get sick.

Check shows there 
are places where
backflow may
occur, but there is
no device to prevent
it occurring.
Install devices
to stop backflow
where they are
needed.

Water is
discoloured, or
tastes or smells
bad.

People who drink
the water get sick.

Signs of damage to 
a part of the supply.

Water is
discoloured, or
tastes or smells
bad.
(Some places were these
devices may be needed are:
swimming pools; stock
troughs; boilers; tanks used
for preparing agrichemicals;
school laboratories.)
C1.8.6

Vandalism or
sabotage.

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.
Ref W1
Version 1, January 2014

Check for
signs of
damage.

People who drink
the water get sick.

Repair or
replace
damaged
components.
Provide
protection to
stop future
damage.
Water Safety Plan Guide:
Small Rainwater Supply
15
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
Monitoring
Event: WATER TEST RESULTS UNRELIABLE10
Possible hazards: Germs, chemicals.
Level of risk: High

C1.9.1
Samples
taken
wrongly.

Get advice from a health

protection officer 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 there is no
contamination of the
sample
– 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.

Buy a copy of
the DWSNZ 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.

Check with the
operator if there
are things about
the system they
do not
understand.

Make plans to
get the operator
the training they
need.

Find enough
money to train
the operator.
Prepare a sampling plan to
record when and where
samples need to be taken,
and who is to take them.
Staff training
Event: TREATMENT NOT OPERATED PROPERLY
Possible hazards: Germs, chemicals.
Level of risk: High
C1.8.1
Operator
not trained
well
enough.

Get experienced operators to
pass on their knowledge to
new operators.

Make sure the operator
understands:
– 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 operator
training courses.11

Put some money aside to help
pay for operator training.

How well the
supply runs.

Things happen
in the supply
that result from
poor staff skills
and/or
knowledge.
10 The laboratory may also make mistakes, but the concerns here are mistakes that the water supplier can tackle.
11 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.
16
Water Safety Plan Guide:
Small Rainwater Supply
Ref W1
Version 1, January 2014
Improvements
Comparison of the information in the Risk Information Table with the actual supply, shows
the following problems:

Many of the roofs are over-hung by trees. The roof areas under the trees may be
contaminated by the droppings of birds or animals.
Action needed: The trees need to be pruned back, probably on a regular basis.

The ultra-violet disinfection system does not have a light sensor to show when the light
intensity is too low to kill germs.
Action needed: A new disinfection unit is needed, or the modification of old one.

The access openings in the roofs of the water storage tanks have not been designed
properly. As a result, when it rains, water running from the roofs of the tanks can run
directly into the stored water.
Action needed: A lip needs to be built around the edge of the opening, and sealed so
that water runs around and away from the opening.

The hatches for the tanks are presently unlocked. Vandals could get access to the
water.
Action needed: Buy padlocks and fit them to the hatches.

The caretaker is unsure of what to do when taking monitoring samples. Unless samples
are taken properly, reliable information about water quality will not be available to
help judge how well this plan is working. Also, the school will be unable to show that
its water supply complies with the Drinking-Water Standards for New Zealand.
Action needed: Contact the District Health Board and ask for assistance from an HPO
to come and show what has to be done when samples are to be taken.
These problems show that in the Greendell School supply, two of the four key barriers needed
to protect a water supply are incomplete. Some important steps that could be taken to protect
the raw water from contamination have yet to be taken, and although there is disinfection, it
may not be working properly because there is no check on the light intensity.
The order for these actions is listed in the following Improvements Schedule, and 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 W1
Version 1, January 2014
Health
Can the
priority improvement be
made within the
next few weeks
Staff
time
Water Safety Plan Guide:
Small Rainwater Supply
17
1
Cut back trees.
High
2
2
Install a UV unit with a
light intensity sensor
correctly positioned.
High
1
3
Modify storage tank
openings to keep rain
from running off into
the tanks.
High
3
4
Provide locks for
storage tank hatches.
High
5
5
Train the caretaker in
how to take monitoring
samples.
High
4
Yes
Low
1
Cost – chainsaw petrol for
working bee.
3
Cost of a new UV unit cannot be
met by the school’s operating
budget. A request for funding will
have to be put to the Ministry of
Education. The request can be
made fairly quickly, but it will not
be possible to schedule this
improvement until we hear back
from the Ministry.
$300
4
Cost – local engineering firm to
make up new hatch mountings.
$25
5
Cost – three padlocks.
$0
2
$10
No, but work can Moderate
$5000
start on it soon.
(new UV unit).
Probably not
Low
#3 must be done Very low
first
Yes
Low
The school’s annual budget for operation of the water supply is $200. Improvements #1, #4
and #5 could therefore be afforded this year, but funds will have to be carried forward to next
year to provide enough funding for Improvement #3. Improvement #2 is well outside what
the school can afford, and funding assistance will need to be requested from the Ministry of
Education.
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 Public Health Risk Management Plans for Drinking-Water 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, you will have to compare the
five improvements in the way discussed below in “Column 4” for the Greendell School
example.
Column 4: In this column you give each improvement a ranking (from 1 to 5 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
Greendell School improvements are as follows:

Even with all steps taken to protect the roof from contamination, there will always be
the possibility of some contamination getting into the raw water. Fixing the problem
with the disinfection system is therefore more important than the improvements that
affect the raw water quality. Therefore Improvement #2 is ranked “1”.

Improvement #1 is considered more important that Improvement #3 because more
contamination is likely to get into the water from the roof than into rain running into
the tank through the hatches. Therefore Improvement #1 is ranked “2”.

Correct monitoring of water quality indicates when barriers to contamination are not
working. But it is more important to have barriers in place to prevent contamination
in the first place. In the case of Greendell School, Improvement #3 is therefore
considered more important than Improvement #5, and Improvement #3 is ranked “3”.
18
Water Safety Plan Guide:
Small Rainwater Supply
Ref W1
Version 1, January 2014

Vandalism or sabotage of the Greendell School supply is considered very unlikely to
happen, and having reliable information about the quality of the water is more
important. Therefore Improvement #5 is ranked “4”, and Improvement #4 “5”.
Making decisions about the health importance of improvements can be difficult. If you have
a long list of improvements, sorting them into categories such as “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 easy each improvement is to make. Work on
improvements that can be made easily and quickly should be a given 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 for
attention you are able to give it. In Column 6 you can note down whether you think this work
is likely to take up much staff time. In the Greendale School example, a number of the
improvements will probably take up only an hour or two of staff time. Getting a new UV
system installed may take more time than the others for both the head teacher, who will have
to prepare a case to the Ministry of Education for funding, and the caretaker who will need
some training in how to use it. 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.
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: #1 – give it top priority.

Are there any other improvements that can be made easily and at little cost?
Yes: #5 – give it priority 2.

Are there other improvements of high health priority?
Yes: #2 – this improvement cannot be made immediately because of its cost, but work
can start on preparing the case for funding from the Ministry of Education. Give it
priority 3.

Are there any remaining improvements?
Yes: #3 and #4 – #3 is of higher health importance, and although #4 is easy to do and
costs little, it cannot be done before #3. #3 and #4 therefore have priorities 4 and 5
respectively.
In situations where there is an Improvement of 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
Ref W1
Version 1, January 2014
Water Safety Plan Guide:
Small Rainwater Supply
19
Greendell School example, although Improvement #2 (high health importance; high cost) is
not given top overall priority, work can start on it at about the same time that work starts on
the two higher ranked improvements.
Column 9: This column can be used to provide notes about an improvement where needed.
20
Water Safety Plan Guide:
Small Rainwater Supply
Ref W1
Version 1, January 2014
Action timetable
Action
Improvement
completed
Completion date
Person responsible
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.
4 Feb 2002
Head Teacher
Contact public health service to arrange a visit
by an HPO to train the caretaker in taking
samples.
7 Feb 2002
Head Teacher
PTA meet to arrange working bee to cut back
trees.
13 Feb 2002
PTA Chairperson
Working bee to cut back trees.
23 Feb 2002
PTA Chairperson
1
HPO visit to talk to caretaker and a teaching
member of staff about sampling and to
demonstrate how and where to sample.
4 Mar 2002
Head Teacher
5
Prepare a case to the Ministry of Education for
funding for up-grade or purchase of a new UV
disinfection unit.
29 Mar 2002
Head Teacher
Decide whether trees need to be pruned again,
and if so ask the PTA to arrange a working bee.
(This needs to be done each year.)
7 Feb 2003
Caretaker
Contact an engineering firm to arrange for them
to visit the storage tanks, make measurements
and manufacture new hatches to meet
requirements.
15 Mar 2003
Caretaker
Have new hatches fitted.
17 May 2003
Caretaker
3
Purchase padlocks, fit to hatches, and lock.
20 May 2003
Caretaker
4
Obtain, and have installed new UV unit, or
modification of existing unit.
Date cannot be fixed
until reply from
Ministry of Education
received.
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, if responsibility is not part of the job description, 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 ensure that these
improvements are not overlooked.
Ref W1
Version 1, January 2014
Water Safety Plan Guide:
Small Rainwater Supply
21
Regular Checks and Maintenance
Schedules
The following table summarises checks that are carried out on the Greendell School 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

Check the Drinking-Water Standards
for New Zealand for details, or get
advice from an HPO if needed
How often
Responsibility
Monthly
Caretaker
2
Tree growth

Trees overhanging the roof
Annually
Caretaker
3
State of roof and
guttering

Animal/bird droppings
State of repair of roof

Quarterly
(once every
three months)
Caretaker

Deposits (eg from chimneys)

Unexpected objects (vandalism)

Mesh and grills displaced or missing
so animals can get into the tank
Monthly
Caretaker

Signs of vandalism

Build up of sediment

Water levels (warning of water
shortage)
4
Tank (external and
internal)
Annually
(sediment)
5
Appearance of the
water

Cloudy or discoloured
Daily
All staff
6
Difference between
the filter’s inlet and
outlet pressures

Low difference means a filter
problem
Daily
Caretaker
7
Minimum water
temperature

Poor UV disinfection at low
temperature
Daily during
winter
Caretaker
8
Parts of the
reticulation that might
be easily damaged

Signs of damage
Daily (while
moving around
the school)
Caretaker
9
New situations that
might lead to water
being sucked back
into the drinking-water
supply
Annual
Caretaker
10
Water pressure at taps
Daily
Caretaker
22

Lower pressure than usual
Water Safety Plan Guide:
Small Rainwater Supply
Ref W1
Version 1, January 2014
A number of the daily checks noted in the table can be made by any staff during their
movements about the school each day, and any concerns passed on to the caretakers.
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
Filter (including replacement) – follow manufacturer’s instructions
Caretaker
2
UV disinfection unit – follow manufacturer’s instructions
Caretaker
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 W1
Version 1, January 2014
Water Safety Plan Guide:
Small Rainwater Supply
23
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 – Roof contaminated by spraydrift or overspraying
Indicators:
Required
actions:
Responsibility:
24

Spraydrift or overspraying reported.

Noticeable taste or odour.

Test results.

Reported illness in the community.

Stop using the water. Find another source of drinking water
until water of acceptable quality can again be supplied.

Identify the person or organisation doing the spraying, and if
possible, the product used. Inform the MOH.

Drain contents of tank.

Disconnect down pipe from tank.

Clean roof and tank.

Reconnect the down pipe to the tank.

Check that no more chemical is getting into the water by having
the water tested again after the next rain, BEFORE using the
water for drinking.

Record details of incident and provide ESR with this
information for entry into its spray drift database – Driftnet.

Modify your water safety plan if necessary.
Head teacher.
Water Safety Plan Guide:
Small Rainwater Supply
Ref W1
Version 1, January 2014
Event – Volcanic activity leading to ash fall on the roof
Indicators:
Required
actions:
Responsibility:

Media reports of an eruption.

Ash fall in area.

Disconnect down-pipe from tank.

Normal range of conductivity values need to be known before
the event. Get help from a health protection officer from the
district health board in getting these measurements (and for later
measurements noted below).

Check quality of tank water through conductivity and pH tests.

If conductivity value is not elevated and pH is above 5, continue
use of tank water. If conductivity has increased (estimated
increase of 5–10 mS/m) or pH is depressed below 5, provide
another source of potable water until water of acceptable quality
can again be supplied.

When ash fall is complete, clean roof surface, guttering and
down pipe, plus tank if necessary.

Have water samples taken to check for raised levels if heavy
metals, and other chemicals of possible concern.

Modify water safety plan if necessary.
Head teacher
Event – Water shortage
Indicators:
Required
actions:
Responsibility:

No rain.

Water level in the tank is low.

Increased levels of turbidity as water is drawn from lower levels
of tank.

Provide another source of potable water until water of acceptable
quality can again be supplied.

Find ways of reducing water usage.

Identify the reason for the lack of water. The obvious is lack of
rain, but there may also be loss of water because of leaks.

If changes in weather patterns are likely to cause shortages of
water often, install an additional or bigger tank, or find a
supplementary or new source.

Modify water safety plan if necessary.
Head teacher.
Ref W1
Version 1, January 2014
Water Safety Plan Guide:
Small Rainwater Supply
25
Event – Contamination enters the reticulation
Indicators:
Required
actions:
Responsibility:
26

The water is cloudy, or the cloudiness is changeable.

In 100 ml samples of water from the reticulation, E. coli is
continually found or is present at levels more than 10 per
100 mL.

People using the water complain of its taste and smell 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.
Head teacher
Water Safety Plan Guide:
Small Rainwater Supply
Ref W1
Version 1, January 2014
Water Safety Plan Performance
Assessment
Each year this plan is to be checked to make sure it is effective. This is done by:

checking the water quality that has been shown by the monitoring done for compliance
with the Drinking-Water Standards for New Zealand

seeing whether any problems have been found during checks (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 roofs,
new events should be added to the Risk Information Table.
If a Contingency Plan has been used, any improvements to the Contingency Plan should be
made.
The head teacher has responsibility for reviewing how well the plan is working and making
the changes necessary.
Ref W1
Version 1, January 2014
Water Safety Plan Guide:
Small Rainwater Supply
27
Reporting
The head teacher has responsibility for preparing a brief annual report on the water supply
and the risk management of the supply to the Board of Trustees, the PTA and possibly the
Ministry of Education if this is needed. 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 ensure the supply
is complying with the Drinking-Water Standards for New Zealand.
28
Water Safety Plan Guide:
Small Rainwater Supply
Ref W1
Version 1, January 2014