Regional Council Votes to Permanently Chlorinate Lower Hutt Drinking Water
Greater Wellington Regional Council has approved the permanent chlorination of Lower Hutt’s drinking water. The Council
voted in favour of a recommendation from Wellington Water, which has completed an investigation into the contamination
of water supplied from the Waiwhetu Aquifer.
Wellington Water has completed multiple reviews, technical assessments, analysed incident reports, and sought advice
from local health authorities and independent international experts about the change in water quality detected since
September 2016. The most significant change is three detections of E.coli between December 2016 and April 2017.
The outcomes of these investigations were considered by the GWRC today.
Greater Wellington Chair Clr Chris Laidlaw says technical experts have provided a solid picture of the environmental and
physical factors that could be influencing the aquifer, but there is no clear evidence of a single cause. Therefore
decisive action is required.
“This is a complex area of study in an aquifer that is yet to be fully explored, and it’s shown us there are no quick
fixes to the issue of contamination. We can’t take chances when it comes to protecting public health, and that means
continuing to chlorinate drinking water from the Waterloo Treatment Plant.”
Wellington Water’s review of the source of the changes at Waiwhetu Aquifer considered a broad range of scenarios,
including the ‘shaking effects’ of the Kaikoura earthquake, pathways into the aquifer via well-casings, and leaking
stormwater and wastewater pipes. Although these scenarios are considered unlikely to be the cause of the changes, they
cannot be completely ruled out.
“We will continue to investigate the aquifer through a longer term study. This will improve our understanding, and
ensure we have the right planning controls in place to protect the aquifer,” says Clr Laidlaw.
Wellington Water took action to continue to provide safe and healthy drinking water to Hutt City customers in April
2017. The decision to continuously chlorinate the water supplied by the Waterloo Water Treatment Plant was taken as a
precautionary measure in April in response to positive E. coli test results and a concerning increase in total coliforms.
Around the same time, a decision was also taken to install ultra-violet (UV) water treatment units to provide further
protection against potentially harmful organisms in water supply. Wellington Water made these decisions in collaboration
with GWRC and Hutt City Council, as well as Hutt Valley District Health Board’s Regional Public Health while
investigations were completed.
Non-chlorinated drinking water will be available from fountains in Buick St and Dowse Square Lower Hutt. Drinking water
at these fountains is now subject to filtration and UV treatment. Regional Public Health support the addition of UV
treatment to the Buick Street and Dowse Square bores as a way of managing potential public health risk.
Lower Hutt Mayor Ray Wallace says no chances should ever be taken when it comes to drinking water quality.
“No one wants a repeat of the Havelock North experience. Public safety has always been our number one priority, and we
must continue to listen to the experts who tell us that a combination of chlorination and UV treatment for our network
is the best long-term approach.
“It’s fantastic that we’re also able to offer an unchlorinated solution in Lower Hutt for those that prefer it at the
Buick Street and Dowse Square fountains. These fountains are now both open and treated with a UV filter and filtration.
At the flow-rate of water from the fountains, the UV and filtration provides effective barriers against possible
contaminants and means the water complies with the Drinking Water Standards of New Zealand.
“While it is sad that this has happened and investigations have not found a single root cause, it is something we must
accept and I am confident that the best possible solution has been found for our city.”