Landowners Reminded to Test Wells

The Waimakariri District Council is reminding owners of private wells to test their water regularly, following a recent pilot study of 19 private wells in the Cust and Eyreton areas.

Nitrate and other chemical parameters were analysed in private wells by the Council, in response to a recommendation from the Waimakariri Water Zone Committee. Cust and Eyreton were chosen specifically as areas for the study because of selected reports of elevated nitrate levels.

The pilot study results highlight the importance of private well owners to understand that they are responsible to undertake their own water monitoring, and what frequency to test their water.

The pilot study found one of 19 private wells with nitrate above the Maximum Acceptable Value (MAV) of 11.3 milligrams per litre (mg/l) nitrate-nitrogen (equivalent to 50mg/L nitrate), as set out in the Drinking-water Standards for New Zealand. The study also unexpectedly found one private well with arsenic and manganese over the MAV in the Drinking-water Standards.

Consumption of nitrate over 11.3 mg/L (equivalent to 50mg/L nitrate) can cause adverse health effects for unborn babies, young infants, and those with rare metabolic disorders. Therefore it is important to test regularly, at least annually, to check that water is safe to drink. Nitrate levels can change seasonally.

“The test for nitrate is particularly important in the inland plains areas of our District, stretching roughly westwards of Rangiora towards the hills” says Council’s Water Environment Advisor Sophie Allen. “Nitrate is just one contaminant that all well owners should look for, with testing also recommended for other potential contaminants such as manganese, arsenic, and bacteria such as E.coli”.

Elevated levels of nitrate over the MAV have been found in an Environment Canterbury monitoring well in the Cust area, and in private wells in Eyreton prior to the pilot study.

Utilities and Roading Manager Gerard Cleary says “Private well owners should have their water checked by an accredited laboratory to ensure water is safe to drink.”

Affordable treatment options exist for nitrate removal. However, many standard filters are not adequate for the removal of nitrate, and advice should be sought from a water treatment specialist on the appropriate filtration system for removal.

Gerard advises “There is no need for landowners supplied by a Council reticulated water scheme to test their water. The Council supplies have regular testing, with no water supply in the District affected by high levels of nitrate or other contaminants.”

Any private well owners who have found nitrate levels over 11.3 mg/L nitrate-nitrogen (equivalent to 50mg/L nitrate) in the District are encouraged to notify Sophie Allen - Water Environment Advisor, Waimakariri District Council.

Find out more about health risks of nitrates in drinking water.

Do you get your household water from a private well?

Recommended Testing Regime:

  • E.coli and bacteria - four times per year (following rainfall where possible)
  • Nitrates - annually (during spring, when nitrate levels tend to be higher)
  • Arsenic - annually
  • Iron - annually
  • Manganese - annually

Contact: Sophie Allen

Phone: 0800 965 468

Email: sophie.allen@wmk.govt.nz