Drinking water

Council water supplies

Community drinking water supplies are regulated by Taumata Arowai, a government agency created in March 2021.

Taumata Arowai is responsible for ensuring that water suppliers provide safe water that meets the drinking water standards. The water quality requirements for drinking water are set in the drinking water standards and drinking water aesthetic values. Local councils often supply drinking water to local communities.

For more information about your council water supply, visit your council's drinking water webpage.

View council water suppliers

Christchurch water supply

Christchurch has a plentiful supply of fresh clean drinking water. Christchurch's aquifers are replenished with 375 billion litres of water each year (JPG file, 80KB), most of which is unused and flows out to sea.

Origin of Christchurch’s groundwater

Around three-quarters of Christchurch’s groundwater comes from the Waimakariri. Water seeps through the river bed and into the groundwater, which flows toward the city at a rate of about 25 metres per day.

Rain that falls on the land west of Christchurch also contributes to the groundwater system. Recent information suggests that some of the deepest groundwater beneath Christchurch may come from rain and irrigation water that falls on the land to the north of the Waimakariri River.

Protecting Christchurch’s groundwater

We work with the community to help ensure we protect our freshwater now and for generations to come. People from across our region are working together as kaitiaki to protect and improve our water resources.

Christchurch’s groundwater is famously pure at its source. To ensure it stays pure, the area above the aquifer is subject to strict land-use rules under the Canterbury Land and Water Regional Plan to minimise the risk of contamination.

That’s why you’ll find recreational parks and very low-intensity stock grazing in this part of Canterbury.

The Christchurch City Council is the only organisation that can apply to take more water from our aquifer, and it can only do so to use for community drinking water supply.

For information regarding chlorination of the Christchurch drinking water supply, see the CCC website.

Find out more about drinking water protection zones.

Private water supplies

Some properties have their water supplied by a privately owned community water scheme. If your water is supplied by a privately owned scheme, you should contact the scheme's owner directly if you want information. That provider must have a drinking water safety plan or acceptable solution.

Taumata Arowai maintains the public register of drinking water supplies where you can search and find the drinking water supplies in your local area. Some drinking water supplies may not yet appear on the register because of the phased introduction of this requirement for smaller suppliers.

If you own or operate a water supply that is being used as drinking water by people outside of your own home, you are deemed to be a drinking water supplier and will have responsibilities under the Water Services Act 2021.

Our drinking water action plan

While ensuring the safety of privately sourced drinking water is the individual provider’s responsibility, we’re taking the lead in making sure people have the knowledge to make well-informed decisions regarding their drinking water.

In 2025, Council passed a Notice of Motion which included a directive to take a leadership role in raising awareness of the nitrate issue, especially with respect to self-supplied drinking water. Additionally, the Regional Delivery Committee was presented with our Drinking Water Action Plan.

From this work, we've produced an updated nitrate risk map for shallow groundwater in Canterbury, and an estimate of the number and location of properties supplying their own drinking water.

Mapping nitrate risks in Canterbury

The nitrate risk map updates our data on concentrations of nitrate in groundwater. However, the 2025 map contains several changes, including the introduction of “elevated risk” areas.

We informed this map by testing shallow wells (less than 40m below the water table) in our groundwater testing network. Not all wells are used as a drinking water source.

For this map, risk refers to the risk that nitrate concentrations in groundwater from wells in the area could exceed the drinking water maximum acceptable value (MAV) for nitrate. It does not directly inform risk to human health, and does not consider risks associated with any other contaminants.

Within each area, nitrate concentrations in individual groundwater sources will vary due to factors like well depth. Generally, deeper wells tend to provide water with lower nitrate concentrations.

High-risk: nitrate concentrations inmost shallow groundwater samples are likely to exceed the MAV.
Elevated-risk: samples are generally over 50% of MAV for nitrate, and some samples approach or exceed the MAV.
Moderate-risk: nitrate in groundwater will generally be lower than 50% of MAV but occasionally can approach or exceed the MAV.
Low-risk: most of the shallow groundwater samples have nitrate-nitrogen concentrations of less than 3 mg/L and samples are unlikely to exceed the MAV.

Some parts of Canterbury do not include a risk analysis. This is due to the lack of wells or groundwater present, or in the case of Banks Peninsula, where self-supplied drinking water is sourced from streams or rooftop collection.

It is important to note that nitrate is one of several possible contaminants that can be found in drinking water, and these maps do not measure the likelihood of any other contaminants – like E. coli – being present.

Self-supplied drinking water

We commissioned the New Zealand Institute for Public Health and Forensic Science Limited (PHF Science) to produce a report estimating the number and location of properties in Canterbury providing their own drinking water.

The report estimates that more than 20,000 Canterbury households are supplied by self-supplied drinking water. By overlaying the locations of these households on our nitrate risk map, we can estimate the number of self-supplying properties in each risk area, for each council.

Those properties in areas with no known aquifer are likely to rely on non-groundwater supplies of drinking water, such as rainwater or river water, so appear in a risk category labelled "unknown".

Nitrate risk for these households will depend on several factors besides risk zone, including:

well depth
whether the wells are currently used for drinking water
the water treatment is installed
how the well is maintained.

Keeping your private water supply safe

Water can be contaminated by bacteria, viruses, nitrate, metals and other chemicals. Some contaminants occur naturally, while others come from human activities. If you have your own well or surface source, the responsibility to keep your drinking water safe rests with you.

Visit Taumata Arowai's page on domestic self supply for the best guidance.

Find out about actions you can take to keep your water supply safe and test your water supply for contaminants.

Actions to keep your water supply safe

As a private well owner, there are actions you can take to keep your water supply safe, for example:

Learn where your well is located, how deep it is drilled and ensure it’s in good condition.
Protect your well head (the top of the well where it emerges from the ground). Remember, this is your drinking water. Whatever goes down your well ends up in your glass. Follow these simple steps:

1. Well cap - install a secure well cap, and seal between the casing and any hoses or cables going down the well.
2. Well casing - ensure the well casing is elevated at least half a metre above the ground surface.
3. Concrete apron - seal between the well casing and the surrounding ground with a concrete apron. If you're drilling a new well, install a bentonite seal around the casing.
4. Backflow preventer - install a backflow preventer to stop contaminants siphoning back into your well.
5. Area around well - keep the area around the well-head clear of animals, pesticides, fertilisers, compost and rubbish.
6. Sample point - have your groundwater supply analysed if you suspect a problem with the water quality.

Check the historical use of the land to understand possible groundwater contamination risks. In Canterbury, one source of information is the Listed Land Use Register.
There may be metals like lead and copper in the plumbing of your property, such as taps or other fixtures, that can impact water quality. When you first turn on your tap in the morning, run your tap to fill a large cup of water and tip this down the sink. You should also do this at other times when your tap has not been used for a while, like when you come back from holiday.

Regularly test your water supply by taking a sample and sending it to a lab for analysis. Taumata Arowai maintains a register of accredited water testing laboratories around New Zealand.

Testing your water supply

There is potential for a range of contaminants to reach groundwater and surface water. Testing for these is important because drinking contaminated water can have serious health consequences. Contaminants that can be found in our water include the following:

Pathogens (bugs)

Pathogens, such as viruses or bacteria can come from faecal material from grazing animals or animal or human effluent storage and disposal.

E.coli is an indicator of faecal contamination. You should test for E. coli quarterly, especially following heavy rainfall.
Drinking Water Standards for NZ 2022 state that the maximum acceptable value for E.coli is less than 1 in 100 mL of sample.
Seek specialist advice if your water requires treatment for pathogens. Methods could include one or a combination of ultraviolet disinfection, chlorination, and filtration. As an interim solution, boiling water for one minute will destroy most pathogens.

Nitrate

Nitrate can enter groundwater from farming activities, usually through animal urine and fertilisers, as well as from wastewater disposal and landfills. It can remain in the subsoil during dry periods and seep into groundwater following significant rainfall.

We recommend testing nitrate levels annually, preferably during spring or autumn when nitrate levels tend to be higher. You should flush the tap for 10 minutes before sampling.
Nitrate levels can spike after heavy rainfall, especially if that rainfall follows a long dry period. These nitrate spikes are greatest in shallow wells.
Water with nitrate above the maximum acceptable value should not be used to prepare formula for young babies. Pregnant women and parents of new babies should talk to their lead maternity carer about the risks.
Boiling or filters do not remove nitrate from the water.
If your water requires treatment for nitrate, seek specialist advice. Methods could include reverse osmosis or ion exchange.
Drinking Water Standards of NZ 2022 state that the maximum acceptable value for nitrate is 11.3 mg/L expressed as NO3-N or 50 mg/L expressed as NO3.

Learn more about the actions being taken to reduce the risk of nitrate contamination.

Download Risk Maps of Nitrate in Canterbury Groundwater 2022 (PDF File, 2.85MB)

The maps show where we have previously found high levels of nitrate in water samples from wells.

Heavy metals and organic chemicals

Heavy metals include cadmium, lead, manganese and arsenic. Organic chemicals include petroleum compounds, industrial solvents and pesticides.

These contaminants can come from a variety of sources including old sheep dips, landfills and industry.
The Listed Land Use Register (LLUR) is a publicly available database of sites where hazardous activities and industries have been located throughout Canterbury. This can help you identify whether any of these activities have been carried out on or near your property.
Arsenic and manganese also occur naturally in the sediments in some parts of Canterbury and can reach harmful levels in groundwater, especially if the water is low in oxygen. If a water supply has a bad odour (smells like rotten eggs or sour cabbage) or high iron levels causing rusty staining where it comes into contact with air, these are signs that the water is low in oxygen and it is advisable to test for arsenic and manganese.
A test for a full range of heavy metals and organic chemicals can be expensive, but only needs to be done once, unless you notice a change in the water.
Boiling or filters do not remove dissolved heavy metals from the water. Seek specialist advice if your water requires treatment for heavy metals or organic contaminants.

We manage an extensive database of water quality sampling results. Check water quality for a specific site or well number.

Water treatment

If you are concerned about the quality of your water supply, or if testing shows that the water does not meet drinking-water standards, you may need to consider treating the water. Water treatment is complex and requires specialist advice specific to an individual supply.

ESR (Institute of Environmental Science and Research) has produced a comprehensive guide to household water supplies, which can be viewed or downloaded from the ESR webpage.

703.5kB Download brochure: Do you get your household water from a private well?

Nitrates in waterways

Nitrate contamination in waterways is a concern for everyone in Waitaha/Canterbury. Intensive land use, including agriculture, is a leading contributor to increasing nitrate concentrations in groundwater. Other sources include wastewater disposal from septic tanks, sewage treatment systems, and industrial wastewater.

Learn more about the actions being taken to reduce the risk of nitrate contamination.

Support and resources

Contact your local water zone committee.
Learn more about Canterbury's drinking water protection zones and the restrictions on activities within them.
Find out more about drinking water safety.
Information about the supply of safe drinking water to households (PDF File, 4.7MB) that are not connected to town water supplies.