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Published 22/04/2017

Chlorination of Lower Hutt’s water supply to continue

The recent chlorination of Lower Hutt’s water supply is to continue while investigations into the source of recent positive E.coli test results are underway. The water remains safe to drink.

A sample from a bore in the Waterloo wellfield returned a positive E.coli result on 12 April 2017. This was the third positive E.coli result in five months from water sourced from the Waiwhetu Aquifer. This, plus recent water quality testing across the aquifer showing an increasing amount of bacteria activity, has led to the decision to keep chlorinating the Lower Hutt water supply network while investigations are ongoing.

The public fountains at Buick Street (Petone) and Dowse Square (central Lower Hutt) have been closed as a precautionary measure because they can’t be chlorinated.

Chris Laidlaw, Chair, Greater Wellington Regional Council said “The safety of our drinking water quality has not been compromised and we're not taking any chances. We immediately chlorinated Lower Hutt’s water supply in response to the recent positive E.coli test and we’ll continue to chlorinate while we investigate the source of these positive results”.

Dr Stephen Palmer, Medical Officer of Health at Regional Public Health said “In accordance with the Drinking Water Standards, Regional Public Health is notified of all events such as positive E. coli test results. We continue to work closely with Wellington Water and Hutt City Council to ensure the public health risk is properly managed”.

Lower Hutt Mayor Ray Wallace said “There is no issue more important than the safety of our drinking water. We know many residents really value access to unchlorinated aquifer water but public safety will always be our number one priority. We're working together, taking a cautious and vigilant approach, and will continue to do so throughout the investigation”.

Mark Kinvig, Acting Chief Executive, Wellington Water said “The cause of the positive E.coli result and increased bacterial activity isn’t known at this stage and it may be related to the November 2016 earthquake. We’re carrying out investigations into the source but this is expected to take many months to complete”.

Additional information:

  • Wellington Water delivers around 140 million litres of safe drinking water to the people of metropolitan Wellington every day
  • Wellington Water has a rigorous and thorough testing programme to ensure water is safe to drink
  • A routine water quality test on water from a bore in the Waterloo wellfield (Lower Hutt) returned a positive E.coli result on Wednesday 12 April 2017. Other recent positive E.coli results were on 4 February 2017 and 2 December 2016.
  • Chlorination of the water network in Lower Hutt was immediately initiated after each positive result
  • About 70,000 customers in the Lower Hutt usually receive unchlorinated water supply (residents of Wainuiomata, Stokes Valley and Manor Park already receive chlorinated water) and around 330,000 customers in Wellington, Porirua and Upper Hutt already receive chlorinated water
  • Metropolitan Wellington’s water comes from an aquifer, rivers, and, in times of shortage, storage lakes. Water from the rivers and lakes is chlorinated before delivery. Water from the aquifer usually isn’t chlorinated
  • The addition of chlorine to the water as a precaution against contamination means that the water doesn’t need to be boiled before drinking
  • As part of their investigations, Wellington Water will be looking at non-chemical treatment options that will allow the public fountains to be reopened 

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