Water supply and sanitation in New Zealand

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New Zealand: Water and sanitation
Flag of New Zealand.svg
Water coverage (broad definition)100%
Sanitation coverage (broad definition)100%
Continuity of supply (%)Mostly continuous
Average residential water use (l/p/d)281 (2020)[1]
Average domestic water and sewer billNZD$960/year (2020)[1]
Share of household metering50%
Annual investment in WSSNZD$1.8 billion CAPEX (2020/21)[1]
Share of self-financing by utilitiesHigh
Share of tax-financingNil
Share of external financingNil
Decentralisation to municipalitiesIn all regions
Water and sanitation regulatorTaumata Arowai
Responsibility for policy settingShared between Ministry of Health and Department of Internal Affairs
Sector lawHealth Act 1956
Water Services Act 2021
Water Pipeline through Waitakere, New Zealand

Water supply and sanitation in New Zealand is provided for most people by infrastructure owned by territorial authorities including city councils in urban areas and district councils in rural areas. As at 2021, there are 67 different asset-owning organisations.[2]

There is widespread evidence of ageing and failing infrastructure for the three waters (drinking water, stormwater and wastewater), and growing awareness of a multi-billion dollar national infrastructure deficit. In some regions there are forecast to be huge, and in some cases unaffordable cost challenges for local authorities.

The challenges for local government include funding infrastructure deficits and preparing for large re-investments that are estimated to require $110 billion over the next 30 to 40 years.[3] As one example of the scale of expenditure required, in May 2021, the Wellington City Council approved a 10 year plan that included expenditure of $2.7 billion on water pipe maintenance and upgrades in Wellington city, and an additional $147 to $208 million for plant upgrades at the Moa Point wastewater treatment plant.[4]

There are also significant challenges in meeting statutory requirements for the safety of drinking water, and the environmental expectations for management of stormwater and wastewater. Climate change adaptation, and providing for population growth add to these challenges.

A major programme of nationwide reform is being developed by central government, with the aim of rationalizing the provision of services for the three waters. It is proposed that a small number of large publicly owned entities will be established to own and manage the three waters assets across the country. The reforms include complete separation of asset ownership from the existing territorial authorities. The nationwide reform programme is being developed in partnership with local government and iwi/Māori as the Crown’s Treaty partner.[2] In late October 2021, the Government launched its Three Waters reform programme, which aims to centralise the management and provision of water utilities services by 2024.[5][6]

The privately owned water supply schemes that service many small rural areas are not included in the reform programme.


Access to water and sanitation was declared a human right by the United Nations General Assembly on 28 July 2010.[7]

The 2030 Agenda for Sustainable Development was adopted by all United Nations Member States in 2015. At its heart are 17 Sustainable Development Goals, including the sixth of the 17 goals which is to ensure availability and sustainable management of water and sanitation for all.[8] While the New Zealand Government has expressed its commitment to meeting the Sustainable Development Goals, it is yet to announce any specific policy or data strategy for that purpose.[9][10]

Access to drinking water provided by registered suppliers (as opposed to self-supply) can be estimated from the reports into the safety of drinking water from registered suppliers that are published by Institute of Environmental Science and Research (ESR). As of 15 April 2020, the Drinking Water online database included records of water supplied to an estimated population of approximately 4.1 million. This indicates that around 85% of the estimated total population of New Zealand at that date receive water from a registered supplier.[11] The balance of the population (approximately 15%) rely upon small self-managed supplies including roof rainwater collection systems.

In their National Performance Review 2020–21, Water New Zealand reported that 86% of residential properties are connected to a water network, and 85% connected to a wastewater network.[1]

Three waters assets and services[edit]

Key data about the three waters (water, wastewater, and stormwater) is made publicly available in a National Performance Review undertaken by an industry body Water New Zealand. This review has been undertaken annually since 2008, to provide a performance assessment of service provision and the protection of public health and the environment. The participants in the 2020-21 review included 38 (of 64) service providers, with service areas covering 87% of the New Zealand population.[1]


Three waters assets[edit]

The 38 participants in the 2020-21 review (covering 87% of the population), manage assets with a total book value exceeding $40 billion. A summary of assets is given in the table below.[1]

Water Wastewater Stormwater
Treatment plants 339 193
Network length in kilometres 42,559 26,309 18,452
Combined wastewater and stormwater pipelines 243
Pump stations 817 2,942 213

Capital and operational expenditure[edit]

The 2020-21 National Performance Review provides a summary of capital and operational expenditure on the three waters assets.[1]

Type of expenditure Water supply Wastewater Stormwater
Capital expenditure $868M $714M $237M
Interest $56M $85M $31M
Operational expenditure $376M $465M $118M
Total $1,299M $1,264M $386M


Average water and wastewater charges are slightly under $850 per year. However, water and wastewater charges vary significantly around New Zealand. Consumers in some areas are paying over three times as much as for water as those in other areas ($863/year versus $262/year). For wastewater, the range in charges is even greater at over ten times as much ($1,217 versus $116/year). In the most expensive jurisdiction, the average customer will have a water and wastewater bill of over $1,700. For those who depend on the single living-alone superannuation payment, the water and wastewater bill in the most expensive region constitutes over 8% of their income. For those dependent on the sole parent support payment, it constitutes more than 10% of their income.[12]

The challenges for the affordability of modern safe water supplies in small townships were highlighted in 2021 when the Buller District Council proposed to increase the water rates in Inangahua Junction. The increased rate was proposed to be $1800 per household by 2025 (almost four times the current rate), and $2000 by 2030. A former councillor said: "Most people in Inangahua Junction are pensioners; they're on low fixed incomes and they simply have no ability to pay these sorts of fees". The mayor of Buller District said that the planned increases related to the requirements to comply with government-mandated drinking water standards for public water supplies.[13]

Auditor-General review[edit]

In February 2020, the Auditor-General published a report reviewing how well public organisations are managing water resources and delivering water-related services. In the introduction to the report, the Auditor-General observed a lack of clarity about the issues in managing the three waters, how to address them, and who will deliver programmes of work. The statement called for improved national leadership.[14][15]

Asset management and investment planning[edit]

On 29 January 2020, the Government announced the investment of $12 billion in the New Zealand Upgrade Programme, focussing on rail, roads, schools and hospitals.[16]

An economist from Infometrics questioned whether the investment programme was focussed in the areas of greatest need, and pointed to New Zealand's ageing water infrastructure. Their analysis of council expenditure plans found that investment in the three waters is expected to be $17.2 billion over the next decade, split between $11.6 billion in waste and stormwater, and $5.6 billion for water supply. However, more than half of the planned investment in waste and stormwater is to replace assets that are at the end of their working life, with only a quarter of the money allocated for additions and improvements. They claimed that further new investment in water infrastructure is needed to cope with a growing population and the demands of the Government's three waters review, aimed at improving the quality of drinking water, storm water and waste water.[17]

In 2021, the Department of Internal Affairs estimated that investment of $110 billion in the three waters assets could be required over the next 30 to 40 years.[3]

Reform of policy and regulation[edit]

The legal framework includes the Health Act 1956, amended in 2007, the Local Government Act 2002 and the Resource Management Act 1991.[citation needed]

In mid–2017, the Fifth National Government launched a review of the regulation and supply arrangements of drinking water, wastewater and stormwater (three waters). This review ran in parallel with the later stages of the Inquiry into the Havelock North drinking water contamination of 2016. The Three Waters Review was published in January 2019.[18]

In 2019, the Sixth Labour Government announced plans for regulatory changes in response to the Three Waters Review including establishing a new, dedicated drinking water regulator, extending regulatory coverage to all drinking water supplies; providing a multi-barrier approach to drinking water treatment and safety; strengthening government oversight of wastewater and stormwater services; and providing transitional arrangements for water suppliers to conform to the new regulations.[19][20][21][22]

In December 2019, the "Taumata Arowai–the Water Services Regulator Bill" was introduced to Parliament.[23] In addition, the Government indicated that a separate Water Services Bill would be introduced in order to implement system-wide reforms to the regulation of drinking water and source water, and targeted reforms to improve the regulation and performance of wastewater and stormwater networks.[24]

On 28 January 2020, the Minister of Local Government, Hon Nanaia Mahuta, released Cabinet papers and minutes setting out intentions for reform of service delivery and funding arrangements for the three waters services nationwide. The Cabinent paper identified affordability and capability as two key challenges facing New Zealand's three waters service delivery infrastructure. The paper proposed transferring control and administration of three water provision services to a new entity that would focus on the provision of water services.[25] The Government indicated that it would work with local government bodies to explore options for transitioning councils to new service delivery arrangements and investigate opportunities for collaborative approaches to water service delivery.[26]

On 27 October 2021, Nanaia Mahuta confirmed that the Government would proceed with its "Three Waters reform programme" to transfer management of storm water, drinking water and wastewater to four new entities by July 2024. These entities would be managed by independent boards jointly elected by a group set up by councils and Māori iwi (tribes).[5][6] These proposed reforms were criticised by several local council leaders including Mayor of Auckland Phil Goff, Mayor of Christchurch Lianne Dalziel, Mayor of Wellington Andy Foster, and the opposition National and ACT parties.[27][28][29][30] By contrast, Ngāi Tahu's Dr Te Maire Tau, the co-chair of Te Kura Taka Pini (the tribe's freshwater group) welcomed the Three Water reforms, claiming they would improve water services and environmental outcomes.[31]

From November 2021, a working group of mayors and Māori representatives reviewed issues of representation, governance and accountability, and reported back in March 2022 with 47 recommendations.[32] In April, the government accepted 44 of the recommendations. Key changes to the original proposals included providing shareholdings for councils in the four new water entities, and increased legislative protection against future privatisation of the water assets.[33]

Supply of drinking water[edit]

New Zealand enjoys high rainfall, especially within the West Coast region of the South Island and the country is notable for its many large, and sometimes braided rivers. However, although the population is relatively small, the population density in North Island is much greater than in South Island where most of the rain falls.

In New Zealand more than 10% of the population depends on roof-collected rainwater systems for their drinking water – especially in rural areas that are not served by municipal town water supplies. Roof-collected rainwater consumption is also popular because the general public has the perception that rainwater is "pure" and safe to drink. Indeed, the risk of disease arising from roof-collected rainwater consumption can be low, providing that the water is visibly clear, has little taste or smell and, most importantly, the storage and collection of rainwater is via a properly maintained tank and roof catchment system.[34]

The low level of water pollution and the relative abundance of rain-fall ensures that water shortages are relatively uncommon. Regional authorities provide abstraction, treatment and distribution infrastructure to most developed areas. Many municipal systems draw water from deep aquifers thus avoiding the cost of long pipelines. Some of these aquifer fed systems such as that serving Christchurch was of sufficiently good quality that no disinfection of final water was practised until the recent earthquake events. Following restoration of the network the water is no longer chlorinated. Water taken from shallower or less secure aquifers are at risk of contamination.

Water supply volumes and losses[edit]

The 2018-19 National Performance Review includes data about water supply volumes from the participants in the study. Residential consumption is estimated because only around 50% of residential properties nationwide have a meter installed. Water New Zealand noted that in this annual review, the total volume of non-residential water use is under-represented, and residential consumption overestimated, as some participants did not provide volumes of non-residential water use.[12]

Water end use Volume
Non-residential water consumption 127,184,998
Residential consumption estimate 316,963,581
Total network water loss 119,010,271
Water supplied to system 563,158,850

The median of the average daily water consumption across participants is 263 litres per person per day, but there is a large spread in residential water efficiency in different areas.

In the 2019 fiscal year, participants reported 119 million cubic meters of water was lost in their water supply systems, equivalent to over 47,000 Olympic-sized swimming pools. This constituted 18% of the 555 million cubic meters of water supplied to the system.

Treatment of drinking water[edit]

Most drinking water supplied through reticulated networks in New Zealand is disinfected using chlorination. However, some communities have water sources derived from deep aquifers that they consider are "secure" or low risk without chlorination. There is opposition to chlorination in some of these communities. However, Water New Zealand, the industry association that represents 1900 water engineers and specialists, advocates for chlorination of all public water supplies.[35]

Water supplies in New Zealand generally have low concentrations of naturally-occurring fluoride, at levels that are insufficient to promote good dental health. Fluoridation of public water supplies is undertaken in most public water supplies, typically at a rate between 0.7 and 1.0 mg/L. A report by the Office of the Prime Minister's Chief Science Advisor issued in 2021 confirmed previous studies that showed a positive impact of fluoridation on dental health, and no significant adverse effects.[36] In 2021, the Health (Fluoridation of Drinking Water) Amendment Bill was passed, transferring control over the decision to fluoridate drinking water from local councils to the Director-General of Health.[37]

Drinking-water quality[edit]

Havelock North contamination 2016[edit]

From 12 to 29 August 2016 the town of Havelock North experienced New Zealand's largest recorded outbreak of waterborne disease. Campylobacter entered the town's water supply. Of the town's 13,000 residents, 5,500 fell ill, 45 were hospitalised and four died.[38]


In September 2016, the Government announced an Inquiry into the outbreak, in two stages.[39] Stage 1 focused on identifying what happened, what caused the outbreak, and assessing the conduct of those responsible for providing safe drinking water to Havelock North. Stage 2 of the Inquiry addressed lessons learned for the future and steps to be implemented to reduce the likelihood of such an outbreak occurring again. [40] [41] [42]


The drinking water for Havelock North was sourced from an aquifer under the Heretaunga Plains (the Te Mata aquifer) that was thought to be a confined aquifer secure from contaminants. The District Council did not treat water drawn from this aquifer before it was distributed to consumers. During a period of heavy rain, a paddock adjacent to the bore became inundated, and sheep faeces caused contamination of the bore water. The Inquiry found that in July 1998, there had been a previous incident of contamination of drinking water at Havelock North, but that the lessons from that incident had been forgotten. Another key finding was that several of the parties with responsibility for the water supply regime for Havelock North had failed to adhere to the high levels of care and diligence needed to protect public health and to avoid outbreaks of serious illness. The Inquiry concluded that a higher standard of care was needed, similar to that applied in the fields of medicine and aviation where the consequences of a failure could similarly be illness, injury or death.


The recommendations arising from Stage 2 of the Inquiry including wide-ranging proposals for legislative and regulatory changes to drive systematic improvements in the management of drinking water nationwide. The recommendations also included mandatory treatment of all drinking water networks and certain self-supplied systems, and the review of drinking water standards and guidelines. [43]

Subsequent research findings[edit]

The Institute of Environmental Science and Research (ESR) carried out genome-sequencing on the campylobacter strain that was found in sick people during the outbreak. The subsequent research has shown that some people living outside Havelock North, but who visited the area during the time of the outbreak, were also affected. The study suggests that the total number of campylobacteriosis cases traceable to the water contamination could be as high as 8320, with up to 2230 of these living outside of Havelock North.[44]

Annual drinking-water quality report - 2017-18[edit]

The Ministry of Health provides an annual report on the drinking-water quality of all registered networked drinking-water supplies serving populations of more than 100 people. The report for the period 1 July 2017 to 30 June 2018 describes compliance with the requirements of the Drinking-water Standards for New Zealand and progress made towards meeting the requirements of the Health Act 1956.[45]

Performance criteria Population
Water complies with all the legislative requirements under the Act 3,250,000 (84.7%)
Implementation of a water safety plan for the supply has commenced 3,810,000 (99.3%)
Met the bacteriological requirements of Standards 3,751,000 (97.7%)
Met all the monitoring requirements in the Standards 3,531,000 (92.0%)


All significant sized urban developments are served by municipal sewers which drain to modern treatment works with final discharges to river or the sea. Rural communities and isolated housing is served by septic tanks or by chemical toilets or earth closets depending on location and usage. The 135 wastewater treatment plants discharge into the following type of environment:[46]

Estuary 5
Groundwater 8
Lake 1
Land 26
Long Sea Outfall 22
Near Shore Outfall 7
River/stream/drain 62
Wetland 4


In its summary of the findings from the National Performance Review 2018–19, Water New Zealand observed that management of stormwater quality is not yet widespread. Stormwater quality monitoring programmes and/or catchment management plans are in place for just over half the Review's participants. Consents for stormwater discharge are even less widespread. Only eight participants had all stormwater discharges consented. Most commonly, participants had consents for less than 10% of the network, and six participants had no stormwater discharge consents whatsoever.[12]

In 2018, the Auditor-General reviewed the management of stormwater by three councils, to gain insights into how these councils were managing the risk of flooding in their communities. The councils reviewed were Dunedin City Council, Porirua City Council, and Thames-Coromandel District Council. One of the main conclusions was that the three councils had a reactive approach to understanding flood risk, by relying mostly on the information collected after a flood. The lack of forecasting could lead to a poor understanding of the risk and cost of future events, and inadequate preparation. The review also noted that the three councils were spending less than the annual depreciation amount on re-investment in stormwater systems, and that under-investment could lead to stormwater systems failing to contain and minimise flooding.

In the summary of findings, the Auditor-General noted that all councils face challenges when managing their stormwater systems, including ageing infrastructure, limited capacity, managing costs to the community, and having the right people and skills in their organisations. The main recommendations concern the need for improved investment decision making, based upon better information about flood risks, and the performance and capacity of stormwater assets.[47]

See also[edit]


  1. ^ a b c d e f g "National Performance Review 2020-21". National Performance Review. Water New Zealand. Retrieved 13 April 2022.
  2. ^ a b "Central/Local Government Three Waters Reform Programme". Te Tari Taiwhenua - Department of Internal Affairs. Retrieved 30 May 2021.
  3. ^ a b Coughlan, Thomas (26 March 2021). "Government thinks $110 billion needed to fix broken water system". Stuff. Retrieved 30 May 2021.
  4. ^ George, Damian (27 May 2021). "Massive cycleways funding boost as city council signs off on record spend". Archived from the original on 28 May 2021.
  5. ^ a b Manch, Thomas (27 October 2021). "Government pushes ahead with Three Waters reform, will take water services from councils". Stuff. Archived from the original on 27 October 2021. Retrieved 27 October 2021.
  6. ^ a b "Three waters reforms to be mandatory for councils - Nanaia Mahuta". Radio New Zealand. 27 October 2021. Archived from the original on 27 October 2021. Retrieved 27 October 2021.
  7. ^ "Resolution adopted by the General Assembly on 28 July 2010 - 64/292". United Nations. 28 July 2010. Archived from the original on 2 May 2020. Retrieved 30 April 2020. The human right to water and sanitation
  8. ^ "Sustainable Development Goals". United Nations. Archived from the original on 2 May 2020. Retrieved 30 April 2020.
  9. ^ "The Global Goals". Human Rights Commission. Archived from the original on 2 May 2020. Retrieved 30 April 2020.
  10. ^ "Goal 6: Clean water and sanitation". Human Rights Commission. Archived from the original on 2 May 2020. Retrieved 30 April 2020.
  11. ^ "Drinking Water for New Zealand". ESR. Retrieved 4 May 2020.
  12. ^ a b c d "2018-2019 National Performance Review". National Performance Review. Water New Zealand. ISSN 2422-9970. Archived from the original on 2 May 2020. Retrieved 27 April 2020.
  13. ^ Williams, Lois (31 May 2021). "Some West Coasters facing four-fold rise in water rates". RNZ. Retrieved 31 May 2021.
  14. ^ "Reflecting on our work about water management". Controller and Auditor-General. 12 February 2020. Retrieved 7 April 2020.
  15. ^ Morton, Jamie (18 February 2020). "Auditor-General: NZ not managing water well enough". NZ Herald. Retrieved 7 April 2020.
  16. ^ "The New Zealand Upgrade Programme". NZ Government. 29 January 2020. Archived from the original on 1 June 2020.
  17. ^ Coughlan, Thomas (27 January 2020). "Government set to announce $12b infrastructure splurge, with a lot of it going to roads". Stuff. Archived from the original on 1 June 2020.
  18. ^ "Three Waters Review". Department of Internal Affairs. Archived from the original on 2 May 2020. Retrieved 7 April 2020.
  19. ^ "New govt regulator to have 'final say' on safe drinking water". Radio New Zealand. 31 July 2019. Archived from the original on 2 May 2020. Retrieved 7 April 2020.
  20. ^ Nanaia Mahuta (16 September 2019). "Speech for the WaterNZ conference". Beehive.govt.nz. New Zealand Government. Archived from the original on 2 May 2020. Retrieved 7 April 2020.
  21. ^ "New Crown agency will enforce water safety standards". Radio New Zealand. 25 October 2019. Archived from the original on 2 May 2020. Retrieved 7 April 2020.
  22. ^ David Clark and Nanaia Mahuta (25 October 2019). "Independent regulator to make drinking water safe". Beehive.govt.nz. New Zealand Government. Archived from the original on 2 May 2020. Retrieved 7 April 2020.{{cite web}}: CS1 maint: uses authors parameter (link)
  23. ^ Nanaia Mahuta (12 December 2019). "The Water Services Regulator Bill – Taumata Arowai a milestone for drinking water safety". Beehivegovt.nz. New Zealand Government. Archived from the original on 2 May 2020. Retrieved 7 April 2020.
  24. ^ "Have your say on the Taumata Arowai-the Water Services Bill". Scoop. 18 December 2018. Archived from the original on 2 May 2020. Retrieved 1 May 2020.
  25. ^ Nanaia Mahuta (28 January 2020). "Proactive release of Cabinet material about three waters service delivery and funding arrangements" (PDF). Beehive.govt.nz. New Zealand Government. Archived from the original (PDF) on 2 May 2020. Retrieved 26 April 2020.
  26. ^ "Three Waters Review". Hon Nanaia Mahuta, Minister of Local Government. Archived from the original on 2 May 2020. Retrieved 26 April 2020. Progress update – February 2020 – Three waters service delivery and funding arrangements
  27. ^ Wade, Amelia (27 October 2021). "How mayors across New Zealand reacted to Three Waters mandate". Newshub. Archived from the original on 27 October 2021. Retrieved 27 October 2021.
  28. ^ "South Island councils disappointed by govt decision to push through Three Waters reform". Radio New Zealand. 28 October 2021. Archived from the original on 27 October 2021. Retrieved 27 October 2021.
  29. ^ "Wellington mayor disappointed by Government's move to force through Three Waters reforms". The New Zealand Herald. 28 October 2021. Archived from the original on 27 October 2021. Retrieved 28 October 2021.
  30. ^ Palmer, Russell (27 October 2021). "National, ACT promise to return water assets to councils". Radio New Zealand. Archived from the original on 27 October 2021. Retrieved 27 October 2021.
  31. ^ Ngai Tahu (27 October 2021). "Ngāi Tahu Welcomes Three Waters Decision". Scoop. Archived from the original on 27 October 2021. Retrieved 27 October 2021.
  32. ^ Palmer, Russell (9 March 2022). "Three waters reforms: Working group urges government financial backing". RNZ. Retrieved 29 April 2022.
  33. ^ Palmer, Russell (29 April 2022). "Three waters: Councils to be shareholders as government accepts recommendations". RNZ. Retrieved 29 April 2022.
  34. ^ https://www.ruralwaterservices.co.nz/uploads/1/1/8/9/118914627/water-tank-info.pdf[bare URL PDF]
  35. ^ Lee, Julian (26 May 2018). "The South Island towns (and city) fighting chlorinated drinking water". Stuff. Retrieved 12 November 2021.
  36. ^ "Fluoridation: an update on evidence". Office of the Prime Minister's Chief Science Advisor. 11 October 2021. Retrieved 12 November 2021.{{cite web}}: CS1 maint: url-status (link)
  37. ^ Smith, Anneke (9 November 2021). "Health (Fluoridation of Drinking Water) Amendment Bill passes final reading in Parliament". RNZ. Retrieved 12 November 2021.
  38. ^ "The Economic Costs of the Havelock North August 2016 Waterborne Disease Outbreak" (PDF). Ministry of Health. 25 September 2017. Archived from the original (PDF) on 2 May 2020. Retrieved 3 April 2020.
  39. ^ "Havelock North Drinking-Water Inquiry established". Attorney-General, Hon Christopher Finlayson. 12 September 2017. Archived from the original on 2 May 2020. Retrieved 3 April 2020.
  40. ^ "Government Inquiry into Havelock North Drinking Water". Department of Internal Affairs. Archived from the original on 2 May 2020. Retrieved 3 April 2020.
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  42. ^ "Report of the Havelock North Drinking Water Inquiry – Stage 2". Department of Internal Affairs. 6 December 2017. Archived from the original on 2 May 2020. Retrieved 3 April 2020.
  43. ^ "Report of the Havelock North Drinking Water Inquiry: Stage 2" (PDF). Department of Internal Affairs. December 2017. Archived from the original (PDF) on 2 May 2020. Retrieved 7 April 2020.
  44. ^ Kitchin, Tom (13 July 2020). "Havelock North campylobacter study estimates 8320 were infected". RNZ. Archived from the original on 13 July 2020.
  45. ^ "Annual Report on Drinking-water Quality 2017–2018". Annual Review of Drinking-Water Quality in New Zealand. Ministry of Health. 27 June 2019. ISSN 1179-2604. Archived from the original on 2 May 2020. Retrieved 27 April 2020.
  46. ^ Ministry for the Environment:How many municipal wastewater treatment plants discharge to land, sea, lake, river?
  47. ^ "Managing stormwater systems to reduce the risk of flooding". Office of the Auditor-General. 10 December 2018. Archived from the original on 1 June 2020.

External links[edit]