Investigation into Ruakaka Treatment Plant closure under way

Production was stopped at the Ruakaka Treatment Plant after an unknown infiltrator upset the treatment process. Photo / Supplied

An investigation into what caused the closure of the Ruakaka Treatment Plant could take up to three weeks.

Production at the treatment plant was stopped last Tuesday, and Bream Bay residents were urged to conserve water.

The treatment plant takes water from two sources, Wilson's Dam and the Ruakaka River and council staff believed the plant took something in from the Ruakaka River which upset the treatment process at the plant.

Due to high turbity - haziness or cloudiness of the water - from the filters, the treated water had to be disposed of.

The plant was back up and running at about 8.30pm on Tuesday evening, but residents were asked to continue to conserve water on Wednesday to bring the levels in the reservoirs back up again.

Whangarei District Council general manager infrastructure manager Simon Weston said after getting the plant up and running, the focus now moved to investigating the cause.

He said it could take two to three weeks to get to the bottom of the issue.

Earlier Mr Weston said the infiltrator was more likely to be a substance than an object.

He said it may never be known what caused the problem, and that the council would need to know what to test for to find out what it was.

The council had asked Northland Regional Council to follow up to see if there was evidence of any substance in the water.