NitrateWatch is helping communities look after their drinking water by offering a free, confidential testing service to measure nitrate levels in drinking water.


If your drinking water comes from a bore or spring, then we would love to hear from you! All you have to do is email us with your postal address and we will send you a free testing kit with all instructions included. Fill the supplied bottle with your drinking water, return it to us in the provided postage-paid bag and wait for your results.

This research project aims to

  • Offer free, confidential nitrate testing of drinking water
  • Map collected data to present nitrate patterns across regions
  • Identify nitrate hotspots in regions
  • Provide visualisation of regional drinking water nitrates
  • Raise awareness and educate the public about nitrates in drinking water
  • Compare nitrate levels across regions

To achieve these aims, our objectives are to

  • Test drinking water submitted by individuals, collect the metadata and display on a map
  • Provide information about nitrates, drinking water quality and how people can protect and monitor their drinking water

The project

What is nitrate and why test for nitrate?

Nitrate is a chemical compound that occurs naturally in the environment by plants which extract the nitrogen from the air. Nitrates are also caused by decaying organic matter from animal and human wastes, and from manufactured fertilisers applied to crops and grass. Nitrates provide nutrients for plants, but too much nitrate can contaminate water and be harmful. Nitrate is made up of 1 nitrogen atoms and 3 oxygen atoms.

Nitrate is soluble in water and is used by plants as a nutrient to grow. When there is too much nitrate, it can be leached out of the soil and into the underlying groundwater.

Where groundwater is used as drinking water for humans and animals, too much nitrate is a health risk, especially for babies fed with formula made from the water. Nitrate contamination is hard to remove, so it is important to regularly monitor nitrate concentrations and monitor when nitrate levels are rising to stop further contamination and keep the water clean.

Excess nitrates in surface water such as streams, rivers and lakes can cause algal blooms and reduce the amount of fish or aquatic organism as the excess algae remove the oxygen and make the water inhabitable for the freshwater organisms.

 Figure 1: A nitrate molecule (NO3)

How to get a free nitrate test kit

Email us to request a test kit. We will send you a sample bottle, instructions and information about nitrate testing as well as a pre-paid postage bag to use to send your sample back to GNS Science.

Standard testing methods are used to measure the nitrate concentration and the results reported directly back to the submitter within 3-4 weeks. Your data is stored confidentially, and we will not release your name, address or exact location of your well to anyone else. Your result is integrated into our database to enable the all results from each region to provide a picture of the environmental health. Together, your result will support nitrate trends in your region and determine whether the drinking water quality meets acceptable New Zealand drinking water standards.

What do the results mean

Nitrate levels are reported in milligrams of nitrate per litre (mg/L). Ministry of Health has set a Maximum Acceptable Value (MAV) as 11.3 mg/L for nitrate-N or 50 mg/L for total nitrate in drinking water. We report all values as nitrate-N, so if you sample exceeds 11.3 mg/L it is above the recommended drinking water standard guidelines and should not be consumed.

A result between 0 to 1 mg/L is the optimum result for drinking water. More than 80% of New Zealand’s drinking water has a nitrate values less than 1 mg/L. We expect only a very small number of drinking water wells have nitrate concentrations that exceed MAV, but with changing land-use, climate change and more pressure on irrigation water takes, it is important that we monitor the situation carefully to ensure Te Mana o Te Wai is not compromised.

Latest nitrate map

The latest nitrate results from your area are mapped below. Move the pointer on your computer over the different sites to get information on the nitrate values in your region.

The latest nitrate results from your area will be mapped here when enough data is gathered. Updated 21 July 2022

Preventing nitrate for entering your drinking water

The safest groundwater comes from confined aquifers under areas that have little access by people or animals and where there is no intensive agriculture or industry. This is not always possible so it’s very important to take all necessary steps to prevent contamination. You should:

  • construct your bore in a safe location
  • dig a deeper bore to access a confined aquifer (if possible)
  • seal and protect your bore from contamination
  • regularly inspect your bore for damage
  • keep nitrate sources (and other chemical hazards such as pesticides etc) away from your bore

Find more information about protecting your bore from contamination in HealthEd's pamphlet Secure Groundwater Bores and Wells for Safe Household Water(external link).

Research programme details

3 years

Funding platform

SSIF Groundwater


Phase 2: July 2022 to June 2023; Phase 3: July 2023 to June 2025

Project leaders

Karyne Rogers
Diane Bradshaw
Conny Tschritter



Find more content related to:

GNS Science topics