Do not drink notice issued - nitrate levels breach acceptable levels in Lower Waihao

Today, the Water Services Authority – Taumata Arowai (the Authority) was advised by the Waimate District Council that nitrate levels in the source water for its Lower Waihao rural water supply have breached the maximum acceptable value (MAV) for drinking water of 50 mg/L and a do not drink notice has been issued. Around 650 households are affected. 

Steve Taylor, Head of Operations at Water Services Authority – Taumata Arowai, says, “An exceedance of the MAV for nitrates poses an immediate risk to some people’s health particularly pregnant women and babies if they consume the water. This differs from the MAV for arsenic which has been an issue in the Waikato and Auckland areas over the past week where the risk is based on long-term exposure.   

“Waimate District Council is responding to the current situation and is using all available communication methods to advise consumers to cease the use of the Lower Waihao rural drinking water supply (including Waikakahi East) for direct consumption or cooking. Boiling water will not make the water that has levels of nitrates exceeding the MAV safe to drink. An alternative supply of tankered water is available for consumers with locations available on the council’s websiteoutbound.   

“Elevated levels of nitrates in the source water for the Lower Waihao rural water supply are a known and ongoing issue. The Authority monitors the management of this by Waimate District Council. 

“Since October 2024, Waimate District Council has detected rising nitrate levels in the Lower Waihao source water and has been proactively informing the Authority of the results and its approach in response.  

Source water treatment processes used by Waimate District Council do not significantly reduce the level of nitrate.  

“We encourage private suppliers and domestic self-suppliers with bore sources to have their water tested for nitrate levels by an accredited laboratoryoutbound, particularly if it is being consumed by pregnant women or babies. The water should also be tested for the presence of bacteria as it is important your water is microbiologically safe.  

“The Authority is monitoring the situation closely and will continue to work with the Waimate District Council to ensure the appropriate steps are being taken to manage the issue.” 

The Council is continuously monitoring nitrates within the supply and will advise consumers when it is safe to reuse the water supplies. If you live in the Waimate District Council area, keep up to date with the Council’s advice and check its website regularly at Waimate District Counciloutbound (waimatedc.govt.nz). 

For more information: 

Maximum amount of nitrate acceptable in drinking water

Nitrate in drinking wateroutbound – Health New Zealand