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2. Drinking Water Management

2.1 Introduction

It is useful to have a basic understanding of how drinking water is managed in New Zealand to effectively implement the NES. This chapter gives background information on the processes and organisations involved.

It is important to note, however, that applicants and council officers are not expected to have an in-depth knowledge of drinking water management to carry out their functions under the NES.

2.2 Structure of water supplies

Water supplies in New Zealand can generally be divided into three components: source, treatment plant, and distribution system. Figure 3 is a graphical representation of the structure of water supplies. The subsections that follow describe each component.

Figure 3: The components of the water supply system, including a distribution system with two distribution zones

Source: A Guide to the Ministry of Health Drinking-water Standards for New Zealand.

2.2.1 Source

The three main sources for drinking water are:

  • surface water (eg, streams, rivers, lakes)

  • groundwater (water drawn from bores or wells)

  • roof catchment (rain water collected on roofs and stored for later use).5

Often water suppliers have limited control over activities in the catchment of their surface water source or in the recharge zone of a groundwater source.6 This means they have very limited control over the quality of the source water they have to treat. Suppliers are also unlikely to be informed if there is a change of activities in their catchment that could lead to a decrease in source water quality. The NES was put in place to rectify this situation and give drinking water quality more weight as an issue.

2.2.2 Treatment plants

Treatment plants range from large operations that consist of a series of treatment processes running under automated control, through small plants using a manually controlled single treatment process, to a single pump drawing water from a source (usually groundwater) without any treatment. Where drinking water is drawn straight from the source and there is no treatment, the Ministry of Health regards the bore head as the treatment plant.

2.2.3 Distribution system

Distribution systems carry water from the treatment plant to the consumers. The Ministry of Health defines the distribution system as the pipes, water storage facilities (tanks or reservoirs) and any other components situated between the treatment plant and the consumer’s property boundary. Storage facilities at the treatment plant are not considered to be part of the distribution system; they are regarded as part of the treatment plant.

Distribution systems can be divided into separate distribution zones. The quality of water within a distribution zone should be consistent.

2.3 Local management: drinking water suppliers and public health units

The following organisations and groups play a part in the distribution, treatment and management of drinking water:

  • water suppliers, who produce and supply drinking water for their consumers

  • health protection officers and drinking water assessors working within the public health units of district health boards, who are responsible for checking whether water suppliers meet the requirements of legislation and the DWSNZ, and can also provide advice where required

  • the Ministry of Health, which develops legislation, provides ‘tools’ and support material to water suppliers to encourage and assist with good management of water supplies, and distributes support funding when available.

All these organisations and groups are likely to have information and knowledge that can help councils implement this NES.

The Ministry of Health maintains a database of public health services on its website
(see It includes contact details for the public health units.

2.3.1 Drinking water suppliers

Most of New Zealand’s population is supplied with water by their local authority water suppliers (city or district councils). In Auckland and Wellington, residents are supplied by the local authority’s retailers, who in turn receive their water from bulk water suppliers. The bulk water supplier in Auckland is the quasi-public-owned company Watercare Services Limited, and in Wellington it is the regional council. Other suppliers include:

  • government departments, such as Defence (military bases), Justice (prisons) and Conservation (national parks)

  • schools

  • large industries, which may provide water to a substantial number of workers

  • camping grounds

  • private individuals or groups of individuals, including marae.

The water supplier is responsible for providing safe drinking water to their consumers. Local authorities running water supplies will employ an engineer or manager with overall responsibility, whereas treatment plants are run by treatment plant operators. When assessing a consent for a discharge or water permit, and when developing permitted activity rules, it may be helpful to contact these treatment plant operators.

2.3.2 Public health units and drinking water assessors

The Ministry of Health and district health boards have responsibilities for public health, which includes undertaking activities to protect health and prevent population-wide disease. Public health units, which operate within district health boards, carry out these activities, including some related to drinking water supplies. Contaminated water supplies can cause widespread illness and are thus of public health importance.

Twelve public health units provide core public health services across the country. Some public health units cover more than one district health board. Two types of staff in public health units may have responsibility for the public health aspects of water supplies: health protection officers and drinking water assessors. Health protection officers have postgraduate training in public health. They may have responsibility for water supplies only, or broader responsibilities that require them to work in other health protection areas or health promotion. Drinking water assessors have received additional training to increase their expertise in water supplies, water treatment and associated regulations.

Refer to the Ministry of Health website for public health unit information, including contact details (

2.4 Health legislation and standards

The Ministry of Health develops legislation and management systems designed to ensure New Zealand drinking water is safe. To support regulatory and legislative initiatives, it has developed a suite of ‘tools’. These gather information about the way in which water supplies are being managed and also help water suppliers provide a safe product by better managing their supplies.

2.4.1 Drinking-water Standards for New Zealand 2005

The Drinking Water Standards for New Zealand (DWSNZ) are prepared by the Ministry of Health and aim to protect public health. The standards set out requirements for safe drinking water and apply only to water that has been treated. These standards work in tandem with the NES to provide a multiple barrier approach to providing safe drinking water.

Despite the name of the DWSNZ, these standards initially had no legal status. However, the Health (Drinking Water) Amendment Act 2007 refers to these standards and gives them legal standing (see below). The DWSNZ are revised every two years and updated every five years. The most recent revision was published in 2005.

The DWSNZ explain how to assess the quality and safety of drinking water by providing two types of information.

  • Water quality standards define the maximum concentrations of contaminants acceptable in safe drinking water. This is done in the form of maximum acceptable values (MAVs), which apply to treated water only. A MAV is the maximum concentration of a contaminant (microbes or chemicals) in drinking water that will not make consumers ill, even if they drink the water all their lives. MAVs provide a yardstick by which the safety of drinking water can be judged. Water is safe to drink if none of the contaminants it contains exceed their MAVs.

  • Compliance criteria specify how a water supplier is to monitor its supply to show that the water it is producing meets the water quality standards. It is the responsibility of the water supplier to show that their water supply complies with the DWSNZ.

The DWSNZ can apply to drinking water supplies of any size, irrespective of whether they are public or private. The standards specify requirements for ensuring that drinking water is safe while minimising unnecessary monitoring.

2.4.2 Health (Drinking Water) Amendment Act 2007

Until recently compliance with the Ministry of Health’s DWSNZ was voluntary. However, health legislation passed in October 2007 changed this situation. The Health (Drinking Water) Amendment Act 2007 requires drinking water suppliers to take all practicable steps to ensure they provide an adequate supply of drinking water that complies with the DWSNZ.

This Act includes a list of dates from which drinking water treatment plants must take all practicable steps to comply. These are set out in Table 1. The larger the drinking water supply, the sooner it must comply.

Table 1: Dates when the Health (Drinking Water) Amendment Act 2007 comes into force (s69c as at 20 May 2009)

Supply type Population served Compliance from
Large > 10,000 1 July 2009
Medium 5001–10,000 1 July 2010
Minor 501–5000 1 July 2011
Small 101–500 1 July 2012
Very small 25–100 1 July 2013
Rural agricultural N/A 1 July 2013

Note: Very small = neighbourhood drinking water supply.

These dates have implications for the implementation of Regulations 7, 8 and 10 of the NES.

The date of particular relevance is the compliance date for water supplies serving more than 500 people: this threshold applies to Regulations 7, 8, 9 and 10 of the NES. If the majority of these drinking water supplies comply by this date, a much greater number of drinking water sources can be assessed under Regulation 7 of the NES rather than under the stricter Regulation 8. (Regulations 7 and 8 are explained in greater detail in section 4.6). Therefore, as time goes on the requirements of the NES will become less onerous as compliance with the DWSNZ becomes more common.

The DWSNZ are also important for the implementation of the NES because they set out the standards that drinking water must meet. The Ministry for the Environment commissioned the Institute of Environmental Science and Research Limited (ESR) to prepare two reports, An Introduction to Drinking Water Contaminants, Treatment and Management: For Users of the National Environmental Standard for Sources of Human Drinking Water and A Guide to the Ministry of Health Drinking-water Standards for New Zealand. Both of these guides were published in 2008 and are available on the Ministry for the Environment website here

Further information about the Act can be found on the Ministry of Health’s website at

2.5 Partnerships and cooperation under the national environmental standard

2.5 Partnerships and cooperation under the national environmental standard

Regional councils have a statutory responsibility for making determinations on whether approval of a consent application is consistent with the provisions of the NES. However, we recognise that regional councils are not experts in drinking water treatment, and the NES does not require that they become so.

Resource consent applicants are expected to include sufficient information with their assessments of environmental effects (AEEs) for council staff to be able to make a decision on how a proposed activity will affect water quality in a drinking water source. Other organisations – chiefly public health units and drinking water suppliers – can assist councils by providing information on how a proposed activity could affect drinking water quality. This could help regional councils to then make decisions on whether an individual resource consent application can be granted in accordance with the NES. If council staff require advice on how a particular proposal would affect drinking water quality, including whether existing treatment will be able to provide safe drinking water if the activity goes ahead, they should obtain advice from expert staff in public health units and/or drinking water suppliers.

The NES does not specify how each agency should operate in implementing the NES. It may be helpful for the agencies in each region that are likely to be involved in, or are directly affected by, the NES to meet to agree on procedures and protocols for handling applications affected by the NES. This could be done by having a regional meeting of agencies with responsibilities for decision-making under the NES, along with those who have public health responsibilities and/or technical knowledge that would assist in assessing the effects of proposed activities on drinking water supplies. Participants could include:

  • regional council staff (including consent officers and regional planners)

  • district council officers (both planning/consent staff and those directly involved in drinking water supply)

  • water suppliers, including treatment plant operators

  • public health unit staff, including drinking water assessors and health protection officers.

All parties could discuss how the NES would best be implemented in their area, including identifying the types of applications that other agencies (eg, public health unit) may wish to comment on. This could include highlighting activities and/or contaminants of particular concern from a public health perspective, and for which consent applications may require particular attention. General discussion of the main water sources in the area could also be helpful, including identifying sources or locations particularly vulnerable to contamination. Water suppliers could give an overview of different types of water treatment in the area, including plants that may be particularly vulnerable to specific kinds of contaminants.

Other issues could include:

  • the types of proposed activity that are most likely to have an effect on drinking water source quality in an area, and thus for which consent applications should be passed on to relevant agencies for comment

  • agencies and/or contacts that regional council policy officers should consult when drafting permitted activity rules in regional plans

  • the process for regional councils referring consent applications for consideration by other agencies

  • the time other agencies would require to consider consent applications

  • how to obtain contact details for water suppliers to place in emergency notification consent conditions.

It may be useful to record any agreed procedures resulting from the meeting. Agencies may even wish to draw up a formal memorandum of understanding to confirm procedures and responsibilities. Annual meetings could be held to evaluate how procedures are working and whether they need to be updated.


5 Roof catchments are mentioned for completeness, but they are rarely a water source that serves large communities of the population size specified in the NES. The catchment activities of concern for this type of source (ie, roof water) are those introducing contaminants into the air, or encouraging the congregation of birds (eg, landfill sites).

6 The exception is for supplies with protected catchments. For example, the majority of Auckland’s water supply is sourced from protected catchments in the Hunua and Waitakere Ranges.