Citation: Ministry of Health. 2014. Water Safety Plan Guide: Construction Materials, Version

Citation: Ministry of Health. 2014. Water Safety Plan Guide: Construction materials, version 3, ref D2.1. Wellington: Ministry of Health.

Published in January 2014 by
Ministry of Health
PO Box 5013, Wellington, New Zealand

ISBN: 978-0-478-42781-3 (online)

Previously published in 2001 as Public Health Risk Management Plan Guide: Construction materials, version 3, ref D2.1. This publication’s title and any reference within the text to ‘public health risk management plan’ was changed in January 2014 to reflect legislation change of the term ‘public health risk management plan’ to ‘water safety plan’. No other changes have been made to this document.

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Contents

Introduction

Risk Summary

Risk Information Table

Contingency Plans

Water Safety Plan Performance Assessment

Appendix 1: Selection of Construction Materials

Ref D2.1Water Safety Plan Guide:1

Version 3, January 2014Construction Materials

Ref D2.1Water Safety Plan Guide:1

Version 3, January 2014Construction Materials

Introduction

This Guide is included with the Distribution System stage of the water supply, but it is concerned with all construction materials that are in contact with water from the abstraction point, through treatment to the distribution system.

Construction materials can cause risks to public health from the following:

• dissolution of the material itself or impurities within it
• contamination getting into the water because of the failure or deterioration of material
• changes in pH caused by dissolution of materials.

If an event associated with construction materials occurs, ie., the quality or quantity of water available is affected by the construction materials, the following can happen:

• If construction materials dissolve and release health-significance chemicals into the water, the chemicals can cause sickness.
• If construction materials deteriorate, germs that get into the water through leaks can cause sickness.
• If organic chemicals in the soil surrounding pipes pass through the pipes into the water, these chemicals can cause sickness.

• If construction materials deteriorate and fail, transmission of water may not be possible and sickness may be caused by poor hygiene and by low pressure allowing germs and chemicals to enter the distribution system.

How quickly construction materials deteriorate is influenced by their chemical (eg, water chemistry, nature of the soil in which pipes are buried) and physical (eg. pressure) environments. By selecting more resistant materials and adjusting the water chemistry (see Guide P8.1) to reduce its corrosiveness, problems caused by the failure of materials can be reduced.

Risk Summary

The event creating the greatest risk associated with construction materials is not being able to supply water because of a materials failure. (See D2.1.1.)

The most important preventive measure is to select materials that are more resistant to dissolution by the water and damage by the surrounding environment. (See D2.1.1.4.)

(References in parentheses are to the Risk Information Table.)

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: MAV – maximum acceptable value – see DWSNZ:2000

• Poor quality materials.

• Ensure selection of only approved or certified materials (having low contaminant content)
• See the Appendix

• Suppliers certificate of performance and quality
• Metals, organics, asbestos associated with dissolution of materials

• Consumer complaints.
• Burst pipes.
• High unaccounted for water use.
• Concentration of chemical determinands originating from construction materials more than 50% of their MAV.
• Maintenance work correlating with consumer complaints

• Change materials or supplier
• Routine cleaning/ flushing

• Inadequate flushing of new materials.

• Develop appropriate protocol for flushing sections of the system to waste where new materials are installed. This may have resource consent implications, and there should be liaison with the region council.

• Maintenance log (check links with consumer complaints)
• Metals, organics, asbestos associated with dissolution of materials

• Cleaning/ flushing in response to an incident

• Inadequate maintenance or replacement of worn materials.

• Develop a “picture” of the condition of your distribution network. Start on the basis of known ages of components, and supplement this with information from observations made whenever maintenance, construction, and other operational activities are undertaken. Note should be made of such things as extent of corrosion, deterioration of cement lining etc..

• Develop a programme of replacement of deteriorating system components prioritised on the results of the previous measure (above).

• Replace deteriorating system components.
• Consider relining where this is possible.

• Materials insufficiently resistant to dissolution by the water and the surrounding environment.

• Ensure materials are resistant to dissolution by the water and the surrounding environment.

• Suppliers certificate of performance and quality.
• Metals, organics, asbestos associated with dissolution of materials.

• Change materials.
• Routine cleaning/flushing

• Ensure the treatment of water minimises its ability to dissolve materials it contacts.

• Metals, organics, asbestos associated with dissolution of materials.

• Adjust treatment

• Deterioration of distribution system, leading to ingress of micro-organisms.

• Develop a routine maintenance schedule including inspection of distribution system condition.

• Maintenance log.
• Microbiological quality.

• E.coli detected in 100 ml sample Intreated water.
• Increased illness in community.
• Burst pipes.
• High unaccounted for water use.

• Develop a programme of replacement of deteriorating pipes and fittings.

• Replace deteriorating pipes and fittings.

• Ensure materials are resistant to the dissolution properties of the water or environment.

• Suppliers certificate of performance and quality.

• Change materials.

• Biofilm development sustaining pathogens.

• Develop a routine maintenance schedule for distribution system cleaning/flushing.

• Maintenance log.
• Heterotrophic plate count.
• E.coli.

• Elevated heterotrophic plate count.
• Consumer complaints.
• Low free available chlorine (FAC).

• Incident-reactive cleaning/flushing

• Ensure materials are:

• Suppliers certificate of performance and quality.

• Routine cleaning/flushing

Notes:

1 – Dissolution of materials that affect the aesthetic properties of the water, eg iron, may create a risk a public health risk by leading to the use of alternative supplies of poorer water quality.

2 – Construction materials in the distribution system are of most concern.

3 – Although of high consequence, the frequency of occurrence is low. Iron fixing bacteria may affect the aesthetic properties of the water and so create a risk a public health risk, by leading to the use of alternative supplies of poorer water quality

• Inappropriate materials in use (predominantly occurs with plastic pipes)

• Investigate the possibility of sources of organic chemical contamination in the soil before laying new plastic pipes.

• Chemical determinands present in the

• Consumer complaints.
• Concentrations of chemical contaminants are more than 50% of their MAV.

• Remove the source of contamination.
• Change the pipe material.

• Materials failure

Contingency Plans

You may need to consult with the Medical Officer of Health to assess how serious a problem is, if an event happens despite preventive and corrective actions you have taken.

• Consumer complaints.
• Elevated chemicals in the treated water originating from construction materials.

• Follow Section 4.4 of DWSNZ:2000.
• Identify the reason for the failure and rectify.
• Monitor chemical until it reaches acceptable limits.
• Record the reason for the failure and the steps taken to rectify.
• Modify the water safety plan if necessary.

• Manager responsible for water supply.

• Consumer complaints.
• Burst or leaking pipes.
• High unaccounted for water use.

• Identify the location of the leak and repair.
• Confirm that hygienic procedures for repairs have been followed.
• Monitor chlorine residuals and increase residual to make sure that more than 0.2 mg/L FAC reaches all parts of the distribution system.
• Follow the procedures in Figure 3.3 of the DWSNZ:2000 to that the microbiological quality of the water is acceptable.
• Identify the reason for the failure and rectify.
• Record the reason for the failure and the steps taken to rectify.
• Modify the water safety plan if necessary.

• Manager responsible for water supply.

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.

• Evidence of material failure (burst or leaking pipes, etc.)
• Elevated chemicals in the treated water originating from construction materials.

• Monthly for chemical determinands, as set out in DWSNZ:2000.

• 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 review show any unusual incidents, indicate that proper procedures are not being carried out, or indicate that poor water quality is reaching customers, then review the procedures for selecting materials.
• 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: e.g., preventive measures are up-to-date; the contingency plan steps are still adequate; and changes to the procedures for selection of materials are recognised in the plan.

Appendix 1: Selection of Construction Materials

For materials used in the construction of a water supply to perform to the level you expect, the water supplier must give consideration to two issues:

• the quality of the products used
• the quality of their installation.

This note concerns the selection of materials. There is presently no agreed New Zealand procedure for the selection of materials, nor or particular overseas or international standards on which materials selection should be based. The following information may help in selecting materials:

1. Two situations may arise when you need to have information about the acceptability of a product:
2. You are considering a particular product for construction work. In this case you may want to know whether it is on an “approved list” or been manufactured to meet a particular standard.
3. You have a construction job, but are searching for a product that can be used for it. In this case you may want to know which products would be satisfactory for the job. (Availability also needs to be considered.)
4. In both instances, you need to know which lists of approved products can be consulted, or which national, or international, standards the product should meet.

Lists of approved or certified products are available from:

• The Drinking Water Inspectorate (UK) maintains a list of products that have been approved under the UK’s Water Supply (Water Quality) Regulations 1989 and the amended regulations 1991. –List of substances, products and processes approved under Regulations 25 and 26 for use in connection with supply of water for drinking, washing, cooking and food production purposes. The list is available as hardcopy, and on the Inspectorate’s website:
• NSF International is a US-based not-for-profit organisation that prepares a wide range of standards, and carried out product certification. NSF provides hardcopy listings of products (also available on their website) that are certified to conform to NSF requirements or standards. Their website address, with information about the standards available, is:

Standards are produced by many organisations. The following are two examples of standards that have been prepared to establish that materials will not leach substances into drinking-water at concentrations that will be a health concern:

• ANSI/NSF Standard 61 Drinking-water System Components – Health Effects
• AS/NZS 4020:1999 Products for use in contact with drinking water.

Some standards and guidelines have been produced by the New Zealand Water and Wastes Association. At the time of writing, standards concerning materials were limited to treatment chemicals, and did not cover construction materials.

Whichever approved list or standard is used, the basis of approval or the purpose of the standard should be checked. Some are intended to ensure the product is mechanically fit-for-purpose; you also need evidence that the product is not going to create a risk to public health because of chemical hazards it contains.

Once a suitable product has been found, the constructing contractor should provide evidence that they have the appropriate qualifications to undertake the work and ensure that the products are properly installed.

Ref D2.1Water Safety Plan Guide:1

Version 3, January 2014Construction Materials