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Warkworth water supply update

Thursday 2 February 2017

An extremely low level of the herbicide Hexazinone was detected in the water produced by the Warkworth Water Treatment Plant – which serves the local Warkworth community – during routine testing carried out by Watercare.

 A recent test detected Hexazinone at a level of 0.0005mg/L in the water produced at the plant.

This level is 800-times below the Ministry of Health’s maximum allowable value (MAV) of 0.4mg/L, as defined in the Drinking Water Standards of New Zealand 2005 (Revised 2008).

Watercare general manager service delivery Shayne Cunis says the company is committed to the delivery of a safe water supply and therefore carries out extensive testing and treatment.

“We have adjusted the operation of the Warkworth Water Treatment Plant to prevent this substance from entering the drinking water supply,” says Cunis.

“Our staff have notified the Auckland Regional Public Health Service (ARPHS) and the Medical Officer of Health David Sinclair. ARPHS have confirmed that they are satisfied with our actions and response to this result.”

Further water samples have been taken and the test results are expected tomorrow.

Hexazinone is a broad spectrum herbicide that is often applied to control woody/herbaceous, annual and perennial weeds. It is known to be soluble in water, highly mobile and can leach from the soil. Watercare has notified Auckland Council’s pollution response team which is the entity responsible for investigating reports of environmental pollution.

In Warkworth, water is sourced from the Mahurangi River.

Watercare publishes detailed water quality reports for all of its water treatment plants each year on its website.