Drinking water assessment

Drinking water is an essential part of our everyday life. Outbreaks of waterborne diseases are a common occurrence, sometimes leading to serious complications and even fatalities.

The Te Whatu Ora Tairāwhiti Public Health, healthy Environments team is responsible for auditing the performance and management of all public water supplies and for providing assistance and advice to small supplies through our Drinking Water Assessors and the Ministry of Health’s Technical Assistance Programme (TAP).

FAQs about Drinking Water

What to look for

Contaminated drinking water

Contaminated drinking water is water that has become mixed with a dirt or other material that may—if there is enough of it—be dangerous to those who drink it.

The majority of council-owned and operated drinking water supplies are considered to be safe.

The most common contaminant of drinking water is animal faecal matter.  Generally, water that has come from rain, a spring or a bore is safer than that from a river or stream which can be contaminated by dirt and faecal run-off from the surrounding environment.

Rainwater quality can be improved if the system is well maintained and steps are taken to protect the supply from contamination during collection and storage.

Underground supplies (wells, bores and springs) vary in quality although protection at the source will often reduce contamination levels.  The degree of contamination in rivers and streams can vary but will undoubtedly increase after periods of rainfall.

How to make sure your supply is safe

Short term or emergency measures

  • Use suitable point of entry filters.  These are large capacity filters installed before the water enters the house.
  • Use good quality water for drinking, hygiene and food preparation other water can be used for other purposes
  • Treating unsafe drinking water by bringing it to a rolling boil or using chlorine (plain bleach)
  • Replace stored water with water from a potable source
  • Clean and maintain the water supply system (general practice).

Long-term measures

  • Protect the water source to exclude animals and dirt
  • Implement a maintenance programme to reduce the risk of  contamination
  • Change to another source that is potable
  • Implement an appropriate water sampling programme.

For more information:

Sampling and analysis

All supplies should undertake some water sampling (monitoring) to ensure that the treatment is working and no contamination of the supply is occurring prior to reaching the consumer.

The level of assurance gained from monitoring is related to the number of samples that are taken over a monitoring period, so low sample numbers gives a low level of assurance.

The main consideration for monitoring is for microbiological determinants because an illness is more likely to be dramatic and widespread when due to microbiological contamination. Nonetheless the supplier should also know whether there are chemicals of concern in the supply but generally, this may be determined by one-off sampling. Check that the laboratory you use is recognised by the Ministry of Health for the analysis they are going to do.


Single building supplies

Single buildings must have a safe and potable water supply as required by the Building Act. For matters relating to the provision of drinking water to new buildings, contact your local council.  

If you are concerned that your water supply may be unsafe or causing you to be unwell, contact us.

Our Health Protection Officers can provide information about possible sources of contamination and the risks. They can also provide advice on how to make drinking-water safe in the short and long term, when sampling and testing may be useful and what the results tell you about the safety of the water supply.


Community supplies

Community drinking water supplies are those non-council owned and operated supplies that serve 25 or more people for more than 60 days a year. This definition includes taps at informal camping grounds and picnic sites, community halls, some marae and Government premises such as prisons, hospitals and rural schools.

If you supply water to your neighbours then you may need to be registered, see registering a community drinking water supply below for more details.

Each community drinking water supply is required to be monitored by the water supplier but Health Protection Officers working for Hauora Tairawhiti may also take some surveillance samples to check on water quality.  All samples are analysed for compliance with the Drinking Water Standards for New Zealand.

Drinking Water Assessors are responsible for reviewing annually all community drinking water supplies serving 25 or more people for more than 60 days a year.  Each supply is reviewed for chemical and microbiological compliance with the Drinking Water Standards for New Zealand.

If a drinking water supply is not listed please contact us.

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