Water Safety Plan
Guide
Treatment Processes
– Fluoridation
Version 1, Ref P9
January 2014
Citation: Ministry of Health. 2014. Water Safety Plan Guide:
Treatment Processes – Fluoridation, Version 1, ref p9. Wellington:
Ministry of Health.
Published in January 2014
by the Ministry of Health
PO Box 5013, Wellington, New Zealand
ISBN: 978-0-478-42756-1 (print)
ISBN: 978-0-478-42757-8 (online)
Previously published in 2001 as Public Health Risk Management
Plan Guide: Treatment Processes – Fluoridation, Version 1, ref p9.
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
Risk Summary
2
Risk Information Table
3
Contingency Plan
6
Water Safety Plan Performance Assessment
7
Ref P9
Version 1, January 2014
Water Safety Plan Guide:
Treatment Processes – Fluoridation
iii
Introduction
This Guide deals with the addition of fluoride to drinking-water to protect teeth against dental
decay. It is not concerned with situations in which too little fluoride is dosed to protect teeth.
To protect teeth, the target fluoride concentration is 0.7 to 1.0 mg of fluoride/L.
If an event occurs during fluoridation (ie, the process doesn’t work properly), concentrations
of fluoride that are too high (more than 1.5 mg/L) for a long time can cause mottling of teeth
and fluorosis.
The chemicals used in fluoridation present risks to the health of treatment plant staff. These
are acknowledged, but are not discussed further as such risks are the subject of health and
safety in employment legislation.
So long as the fluoride is added to the water after coagulation and filtration processes, and
well away from the addition point of any calcium compounds, its effectiveness will not be
reduced.
Ref P9
Version 1, January 2014
Water Safety Plan Guide:
Treatment Processes – Fluoridation
1
Risk Summary
The event creating the greatest risk involved in fluoridation is too much fluoride being added
to the water (see P9.1).
The most important preventive measures are:

regularly check that the dosing solution has been prepared at the right concentration
using the right chemical (see P9.1.1)

put an alarm on the fluoride concentration in the water to let you know when it is too
high (see P9.1.3)

make regular manual checks on the fluoride concentration in the treated water, and in
some cases split the sample and send one portion to an external approved laboratory for
analysis (see P9.1.1, P9.1.3, P9.1.4)

make sure the treatment plant staff are properly trained (eg, in making fluoride dosing
solutions, taking samples and calibration of the fluoride sensor) (see P9.1.1, P9.1.5–
7).
(References in parentheses are to the Risk Information Table.)
2
Water Safety Plan Guide:
Treatment Processes – Fluoridation
Ref P9
Version 1, January 2014
Risk Information Table
Reliable information about water quality is essential for the proper management of a water
supply. Knowledgeable and skilled staff are also essential for minimising the public health
risks associated with water supplies. Please read the staff training (Guide G1) and the
monitoring guides (Guide G2). While we haven’t pointed out every detail of how these
documents are linked with the present document, the links are many and are important.
Abbreviations: DWSNZ – Drinking-Water Standards for New Zealand
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
Event: FLUORIDE CONCENTRATION GREATER THAN REQUIRED FOR DENTAL PROTECTION
Possible hazard: Fluoride
Level of risk: High
P9.1.1
Fluoride dosing
solution (day
tank) prepared
at the wrong
concentration,
or using the
wrong fluoride
chemical, or
spillage of
fluoride
chemical into
solution
preparation
tank.
P9.1.2
Back-siphoning
from day tank.


Make sure chemicals

supplied are delivered
to the correct bins or

containers; clearly label
bins; ensure that
operator is on site when
chemicals are delivered.
Make sure dosing
solution concentration is
cross checked (by a
second person) after
preparation and before
use; check purity of
chemicals supplied.

Train staff in
preparation of fluoride
dosing solutions
(including calculations).

Schedule regular split
samples of fluoridated
finished water to be
analysed by an external
approved, laboratory.

Install a devise to
prevent backflow into
the water supply (see
Guide D2.4).
Ref P9
Version 1, January 2014
Fluoride

concentration.
Supplier’s
certificate of
analysis.
Fluoride
concentration
more than
1 mg/L.

Chemical bins
not labelled.

Checks show
dosing solution
concentration
incorrect.

Notification of
spillage.

Cross checks
not signed off.

Absence of a
backflow
preventer.

Label chemical
bins.

Supplier is
required to ensure
that operator is
present when
chemicals are
delivered.

Instigate checks.

Change supplier.

Identify staff
training needs
and provide
training.

Arrange for split
sample analysis.

Install a backflow
preventer.
Water Safety Plan Guide:
Treatment Processes – Fluoridation
3
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
Event: FLUORIDE CONCENTRATION GREATER THAN REQUIRED FOR DENTAL PROTECTION cont’d

P9.1.3
Dosing system
malfunction.
P9.1.4
Dose rate set
incorrectly.
4
Routine maintenance

schedule for dose
controller, or flow

proportional dosing
system, (whichever is
appropriate) and dosing 
pump (see Guide P10).

Replacement of
controller if suspect.

Ensure that all metering
and dosing equipment
is fail-safe and shuts off
automatically on fault.

Perform cross-checks
each day of amount of
fluoride dosed against
the volume of water
produced.

Install an alarm to
indicate when the
fluoride concentration
exceeds to the target
level.

Regular manual checks
on fluoride
concentration in treated
water, with these
samples being
periodically split and
sent for independent
analysis.

Periodic checks on
fluoride concentration
using an independent
method of fluoride
measurement.
Fluoride

concentration.
Maintenance
log.
Fluoride
weight/
volume
calculations.

Frequent repair
needed.

Maintenance
log not signed
off.

No automatic
shut off in event
of fault.

No evidence of
dose cross
checks having
been carried
out.

Fluoride

concentration.

Calibration
schedule.
Water Safety Plan Guide:
Treatment Processes – Fluoridation
Fluoride
concentration
more than
1 mg/L.

Fluoride
concentration
more than
1 mg/L.

Identify cause of
fault and rectify.

Replace
controller.

Install equipment
with required
safeguards.

Instigate weight/
volume cross
checks.

Manual sampling
and analysis.

Adjust controller
set point.
Monitoring
checks show
deviations from
expected
fluoride
concentration.
Ref P9
Version 1, January 2014
Causes
Preventive measures
Checking preventive measures
Corrective action
Signs that action
is needed
What to check
Event: FLUORIDE CONCENTRATION GREATER THAN REQUIRED FOR DENTAL PROTECTION cont’d
P9.1.5
Controller’s
fluoride sensor
out of
calibration or
malfunctioning
(if dose
controlled by
feedback from
in-line probe).
P9.1.6


Train staff in fluoride
sensor calibration.

Regular manual checks
on fluoride
concentration in treated
water, with these
samples being
periodically split and
sent for independent
analysis.

Use more that one
fluoride sensor so that
any malfunction in one
will become apparent
from mismatch with
readings from others.

Provide staff training in
sampling, and record
keeping.
Monitoring
method
incorrectly
calibrated,
performed
incorrectly, or
analysis
reagents
deteriorated.

Fluoride

concentration.

Calibration
schedule.


Monitoring
samples not
taken, or results 
incorrectly
recorded.
P9.1.7
Regular checks on
fluoride sensor
calibration using
independent calibration
solutions.
Develop monitoring
schedule, with checks
on data entry.

Fluoride

concentration.

Monitoring
schedule.

Monitoring
records.
Recalibrate
fluoride sensor.

Determine reason
for poor
calibration and
rectify.

Identify staff
training needs
and provide
training.

Instigate
monitoring.

Identify staff
training needs
and provide
training.
Fluoride
concentration
more than
1 mg/L.

Identify staff
training needs
and provide
training.
Duplicate
checks show
errors in
measurements.

Instigate quality
control
programme.
Calibration
checks show
fluoride sensor
out of
calibration.
Monitoring
shows fluoride
concentration
out of control
range.
Fluoride
concentration
more than
1 mg/L.

Monitoring
schedule not
followed.

Errors in
records.

Provide staff training in
sample analysis.

Fluoride

concentration.

Develop and use a
quality control
programme, including
periodic split-sample
measurement checks
using an external
approved laboratory.

Quality
control
checks.
Ref P9
Version 1, January 2014

Fluoride
concentration
more than
1 mg/L.

Water Safety Plan Guide:
Treatment Processes – Fluoridation
5
Contingency Plan
If an event happens despite preventive and corrective actions you have taken, you may need
to consult with the Medical Officer of Health to assess how serious a problem is.
Event – Fluoride concentration is higher than maximum acceptable value
Indicators:
Required
actions:
Responsibility:
6

Elevated fluoride concentrations evident from monitoring
samples.

Marked drop in pH (if the fluoride compound is acidic).

Knowledge of a chemical spillage or overdose that may have led
to a high fluoride concentration being produced in the water.

Notify the MOH and shut down the plant if necessary. Provide
another source of potable water until water of acceptable quality
can again be supplied.

Identify the cause of the problem and rectify.

Dump the reservoir water if this is necessary and possible; flush
the distribution system.

Warn consumers to flush their taps thoroughly before resuming
the supply of water.

Record cause of system failure and steps taken to correct.

Modify water safety plan if necessary.
Manager designated responsible for the water supply.
Water Safety Plan Guide:
Treatment Processes – Fluoridation
Ref P9
Version 1, January 2014
Water Safety Plan Performance
Assessment
To make sure that your supply’s water safety plan (formerly known as a Public Health Risk
Management Plan, PHRMP) is working properly, periodic checks are needed. The overview
document outlines what needs to be done. The following table provides the detailed
information for checking this particular supply element.
What to measure or
observe:

Fluoride concentration.
How often:

DWSNZ:2000 Table 4.1 requires a minimum sampling
frequency of 13/quarter for the purposes of P2 monitoring,
but other regulations may require more frequent
monitoring.
What to do with the
results:

Results need to be recorded to meet legislative
requirements or to allow water safety plan performance
assessment. The WINZ database is good for this.

The collected data need to be periodically reviewed to see
whether problems with this supply element are
developing. This should be done as frequently as the
manager responsible considers necessary to minimise risk
to public health arising from this supply element.

Should this view show any unusual incidents, indicate that
proper procedures are not being carried out, highlight poor
laboratory results or indicate that poor water quality is
reaching customers, then review the procedures for
managing the fluoridation process.

Evaluate the monitoring results, and any actions taken as
the result of having to implement a contingency plan, to
see if the water safety plan needs modification – eg,
preventive measures are up to date; the contingency plan
steps are still adequate; and changes to the fluoridation
process are recognised in the plan.
Responsibility:
Ref P9
Version 1, January 2014
Manager designated responsible for the water supply.
Water Safety Plan Guide:
Treatment Processes – Fluoridation
7