The Oxford Rural 1 drinking water supply has two main sources, McPhedrons Bores 1 and 2. Due to an upward trend observed in the nitrate levels in Bore 1 since January 2026, it has now been turned off and is no longer used to supply the community drinking water supply.

Bore 2 is now the primary source and Bore 1 will only be used as a backup source.

Speaking to a report to the Oxford-Ohoka Community Board on Tuesday, General Manager – Utilities and Roading, Gerard Cleary says the water supplied by Bore 1 still fully complies with the New Zealand Drinking Water Standards and the bore has only been turned off as a precautionary measure.

“Council is undertaking investigations to understand the elevated nitrate level trends observed in Bore 1 and will be looking at potential options for managing the issue in the short to long term,” says Gerard.

The maximum allowable limit (MAV) for nitrate in public drinking water is (NO3-N) 11.3 mg/L based on the NZ drinking water standards. Since January 2026 there has been a change observed in the nitrate levels in Bore 1 with levels at or over half of the MAV of 5.65 mg/L observed through routine sampling and testing. Bore 1 has reached a maximum nitrate level of 6.3mg/L based on tests taken since January 2026 compared to the historic median of 4.9 mg/L over the previous 12 months. The nitrate level of Bore 2 is much lower by comparison, at a maximum of 3.9mg/L and a median of 3.5mg/L.

Nitrate testing is undertaken monthly as required by the Drinking Water Quality Assurance Rules (DWQAR) under the Water Services Act.

“Changing the primary supply bore is a sensible precautionary measure. While water from this bore continues to be safe to drink, we acknowledge there is concern about nitrates and have made this decision to ensure that the community continues to receive the best quality drinking water possible.”

All Waimakariri District Council drinking water supplies, including Oxford Rural 1, provide drinking water that is compliant with the New Zealand Drinking Water Standards and are safe to drink.

Over the last 20 years Council has invested over $100m in high quality water infrastructure and we have a 100-year strategy to fund these assets. As part of the long term plan, a further $41 million went towards drinking water safety upgrades.

Nitrate testing results for all Council drinking water supplies can be found on our website.