Private drinking water supplies

Coliforms are a group of bacteria that are commonly found in soil, vegetation and the intestines of animals. Most coliforms are not harmful, but their presence in drinking water can indicate that contamination has entered the water supply.

E. coli is a type of bacteria that is found in the intestines of people and warm-blooded animals. The presence of E. coli in drinking water indicates recent faecal contamination and may mean that disease-causing microorganisms are present. Water containing E. coli should not be consumed unless it has been appropriately treated or boiled.

Some examples of chemicals are Arsenic, Nitrates, Copper, Boron and Manganese. These have maximum limits which are listed in drinking water legislation.

Arsenic is a specific risk in the Queenstown Lakes Region, it can be present in food, plants and in some environments from historic mining activities. While low levels of Arsenic are common and generally not harmful, long-term exposure to high concentrations can pose serious health risks. Health New Zealand | Te Whatu Ora has further information about arsenic, and the University of Otago has substantial information on their Arsenic in the environment webpage.  

In regions with schist rock, (like Otago and the Queenstown Lakes District), arsenic can be present in groundwater due to both natural minerals in the ground, and human activities. This is not unique to our area—other parts of New Zealand, including Hawke’s Bay, Waikato, Manawatu, Marlborough, and Canterbury, also face similar issues with arsenic in groundwater. 

Arsenic cannot be removed by normal treatment processes, so even if your water is treated, you need to test regularly to understand how safe it is.

Another consideration is Aesthetic qualities of your water. These include factors such as Iron, pH, Turbidity, Zinc and hardness parameters. While these are generally not health-related limits, they can affect how your water tastes and behaves, as well as how your treatment system and household equipment performs.

Testing for these parameters can help you understand characteristics such as water hardness and whether scale build up is likely to occur. Over time, scale can reduce the efficiency and lifespan of appliances such as hot water cylinders, dishwashers and pipework. Understanding these characteristics can help you select appropriate treatment and maintenance options for your water supply.

You can see more on Aesthetic Values on the Taumata Arowai website.

It is essential that drinking water is treated with a multi-barrier treatment approach as a key principle of safe drinking water.

If your water comes from a bore or spring, Taumata Arowai has published guidance on protecting these supplies and managing water quality risks.

Because chemical, bacterial and aesthetic levels can vary over time and between water sources, it is essential to regularly test private bore, well or spring water for safety.

Groundwater supplies, like those from private bores, often aren't monitored regularly. This means changes in water quality can happen without anyone noticing. If you’re considering a new water source, make sure it’s tested to check it’s safe to drink.

Most laboratories will have a routine drinking water test suite. Baseline testing parameters include E. coli, Total Coliforms, Turbidity, Arsenic, Boron, Nitrate N, Manganese, pH, Total Hardness, Zinc and Iron. The list is not exhaustive and is dependant of your treatment and on previous sampling findings. Sampling of specific determinands should include any specific environmental hazards/risks relating to your water supply source.

In our district naturally occurring arsenic has been identified as a risk to our drinking water; it is therefore essential to monitor your water supply for arsenic. Make sure you ask to include Arsenic in the testing as it is not standard in a drinking water testing suite. Arsenic cannot be removed through treatment with filters and UV.

Also, remember that weather events like flooding, heavy rain, or power cuts can affect water quality by introducing contaminants. During these times, it’s crucial to boil your water until it can be tested and confirmed safe again. And if you're on the same water supply as others, let them know to do the same.

Testing seasonally or after events such as those listed above helps to ensure your water is safe to drink.

If you are not classified as a water supplier with Taumata Arowai – it is still important to test your water.

Some other important considerations include:

• It’s important to treat bore and spring water as microbial contamination can fluctuate. A multi-barrier treatment system such as filtration and UV can be easily installed. More information about this system.

• Ensuring the bore head or spring collection point is adequately protected from surface water, animals and contaminants.

• Maintaining separation from septic tanks, wastewater disposal systems and stock access areas.

• Inspecting the supply regularly for damage, flooding or changes in water appearance, taste or odour.

• Regularly test your water, baseline parameters may include E. coli, Total Coliforms, Turbidity, Arsenic, Boron, Nitrate N, Manganese, pH, Total Hardness, Zinc and Iron. The list is not exhaustive and is dependant on your treatment and on previous sampling findings. Sampling of specific determinands should include any specific environmental hazards/risks relating to your water supply source.

See more information from ORC.

If your water supply comes from a bore, well or spring water and it hasn’t been tested recently, we strongly recommend getting it tested as soon as possible. If multiple properties share the same water supply, testing can be done collectively for the whole supply.

If you take water from a private bore water supply, a 2021 Otago Regional Council public meeting gives extensive information about the issue across Otago.

To arrange testing, contact your water supplier or an accredited laboratory who can undertake the water testing. For peace of mind, we advise hiring a qualified professional to take the water samples, as they can ensure the correct sampling procedures are followed. They can also guide you to an accredited laboratory for the testing.

• Taumata Arowai, the water regulator, provides a list of accredited laboratories for drinking water testing. Queenstown, Dunedin, and Christchurch all have local labs that can test your water. You can see this list here.

• To arrange testing, contact the laboratory of your choice for a quote and specific instructions on how to collect the water samples, as well as postage and handling requirements.

• When ordering the test, be sure to specifically request arsenic testing, as it’s not always included by default.

Regularly testing your water is the best way to ensure it’s safe to drink.

Registered water testing laboratories

IANZ-accredited laboratories can undertake drinking water analysis. A list of accredited laboratories.

Many laboratories can provide sampling instructions and advice on appropriate tests for private drinking water supplies. They can also send out water test kits and information on how to take an accurate water sample. Alternatively, you can engage a water professional to undertake the sampling.

The first sample and annual samples should be taken from the raw water, before treatment, this ensures that you know what issues may be existing so that they can be treated appropriately.

Best practice is for the water samples to reach the lab under 5°C within 24 hours, however in our region this is often impractical. All efforts should be made to reach best practice, however results can still be effective outside of these parameters.

If laboratory results identify a contaminant above a drinking water Maximum Acceptable Value, the following approach is recommended:

• Review the laboratory report carefully and discuss the result with the laboratory if clarification is required.

• Consider switching to a safe water supply such as bottled water for drinking and cooking until you are satisfied that the water is safe.

• Inspect the supply for potential contamination sources or treatment system failures.

• If E. coli is detected, avoid consuming the water without effective treatment, consider temporary measures such as boiling water or drinking bottled water until the cause is identified and addressed.

• Service or repair treatment systems where required.

• Arrange repeat sampling as soon as practicable to confirm the result or retest the water after corrective actions have been completed.

• Seek advice from a suitably qualified water treatment provider or public health professional if elevated contaminants persist.

Further information is available from the Water Services Authority website.