Health - Drinking water suppliers meeting legislative requirements Year ended June 2019 & 2020

Ministry of Health


Original values and calculations were performed on actual values, then rounded to one decimal place.


The Act groups drinking water supplies into supply size categories according to the population served. The four supply size categories used in this report are large (more than 10,000 people), medium (5,001 to 10,000 people), minor (501 to 5,000 people) and small (101 to 500 people people).

Bacteriological achievement: determined primarily using Escherichia coli monitoring.
Protozoal achievement: based on monitoring the effectiveness of the treatment processes used to remove or inactivate Cryptosporidium.
Chemical achievement: assessed for those supplies that have been identified as containing chemicals that require monitoring (known as Priority 2 determinands).
Overall achievement: assessed on the basis of Escherichia coli and chemical monitoring. There is no requirement to directly monitor for protozoa in the Standards.

Monitoring: provides a check that the water safety plan is operating satisfactorily, and indicates whether remedial action is required.
Provision of drinking water: a requirement to take all practicable steps to ensure the adequacy of supply and in the event of an interruption, planned or otherwise, to take appropriate action.
Source protection: Protection of source waters reduces the number and concentrations of contaminants that the water treatment system has to deal with.
Records: the keeping of records assists water suppliers and drinking-water assessors in determining whether a supply meets the requirements of the Act and achieves the Standards.
Complaints: consumer concerns about drinking-water quality, which often relate to the aesthetic properties of the water (taste, odour and appearance).
Remedial action: appropriate actions in the event that monitoring reveals contamination of the water and that the Standards are breached.

Data calculation/treatment

Population figures are rounded to the nearest thousand (nearest hundred for small supplies).

Limitations of the data

This reporting period included the Alert Level 4 national lockdown due to COVID-19 from 25 March to 27 April and then Alert Level 3 until 13 May 2020. This period of lockdown significantly affected business as usual for everyone, including drinking-water suppliers and drinking-water assessors.


All 486 registered networked drinking-water supplies that served populations of more than 100 people (the supplies) representing 4,142,000 people (the report population).

Data provided by

Ministry of Health

Dataset name

Annual Report on Drinking-water Quality 2020


How to find the data

At URL provided, select 'Annual Report on Drinking-water Quality 2019-2020' from the right-hand column. The data can be found in tables throughout the document, which we have pasted into a spreadsheet for internal processing purposes.

Import & extraction details

File as imported: Annual Report on Drinking-water Quality 2020

From the dataset Annual Report on Drinking-water Quality 2020, this data was extracted:

  • Sheet: Table 2
  • Range: B3:C10
  • Provided: 16 data points

Dataset originally released on:

June 14, 2021

About this dataset

This report summarises drinking-water compliance for all 486 registered networked drinking-water supplies that served populations of more than 100 people in the compliance period from 1 July 2019 to 30 June 2020. The supplies provide water to 4,142,000 people in total. It also describes the compliance of the supplies with the drinking-water requirements of the Health Act 1956 (the Act) and the Drinking-water Standards for New Zealand 2005 (revised 2018) (the Standards).

Method of collection/Data provider

Information on drinking-water quality was obtained from drinking-water assessors employed by district health board public health units, using questionnaires that sought data relating to water supply quality, monitoring and management. The information was collected at the level of the distribution zone. Two surveys were used to gather information.
The first survey sought information about the microbiological and chemical quality of the drinking-water, water treatment processes in use, the means used to demonstrate achievement against the Standards, and the status of water safety plans. This survey utilised the online Water Information New Zealand (WINZ) database.
The second survey sought information relating to the management of the supplies by drinking-water suppliers, in terms of the requirements of the Act that will eventually apply to water suppliers. The completed spreadsheets were returned to ESR for compilation and analysis.