Residents encouraged to have their wells tested for nitrates to ensure levels are safe

Nicole Mathewson Reporter from Northern Outlook

By David Hill, local democracy reporter

Private well testing in the Waimakariri district has found there are no wells above the national standard for nitrate levels.

But a report prepared by Waimakariri District Council water environment adviser Sophie Allen found several wells had nitrate concentrations exceeding the limit set in Plan Change 7 of the Canterbury Land and Water Regional Plan.

"We are continually finding the wells we are testing in Eyreton and Cust are exceeding the limit set in Plan Change 7," Allen said at a recent utilities and roading committee meeting.

"It is about encouraging landowners to agree to have their wells tested."

The maximum acceptable value for nitrate-nitrogen was 11.3 milligrams per litre, set in the Drinking-water Standards for New Zealand (2022).

But overseas studies have suggested that level is too high.

This prompted the Waimakariri Zone Committee to recommend a median value of half of the maximum acceptable value of 5.65 mg/L, which has been set as a target in Plan Change 7.

The council began testing wells in 2019, after concerns were raised by the zone committee, and as now testing about 40 private wells each year.

While the well testing was voluntary, changing national standards meant it could become the council’s responsibility to act on unsafe drinking water in private wells in the future.

The property owners took the samples themselves, usually in the spring, and sent them to the council for testing.

It meant there was no consistency, as some property owners sent in multiple samples, while others chose not to send any.

Environment Canterbury has also been testing private wells throughout the region.

The committee's chairperson, councillor Niki Mealings, encouraged private well owners to submit to testing.

"It is not the end of the world if the numbers come back not great, but it means there are things you need to do to ensure your water source is safe."

Councillor Paul Williams questioned if more could be done to bring newly subdivided properties on to council controlled water supplies.

Three Waters manager Kalley Simpson said new property owners were offered the option of going on to a council supply wherever possible.

"Where it is not a requirement to be on a council supply, they are entitled to put in an individual bore.

"There is value for developers in their marketing to advertise that there is potential to have their water connected to a council supply."

A council booklet was also included in LIMS reports explaining the ongoing maintenance required for private water supplies.

■ Public interest journalism funded through New Zealand on Air.