22 Sep 2016

The Council will bring forward the completion of a programme to replace shallow wells supplying drinking water in the northwest of Christchurch with deeper bores.

The Northwest water zone. Click to view as a pdf

The Northwest water zone. Click to view as a pdf [PDF, 3.2 MB]

In most parts of Christchurch drinking water is sourced from deep wells that carry the highest possible grading for a secure groundwater supply, which is a B.

The northwest water supply zone, which stretches from Belfast through to Yaldhurst and includes parts of Riccarton and Addington, is graded D.  It has 22 shallow wells which supply about 80,000 people.

The shallow, unconfined wells are considered the most susceptible to microbiological contaminants as the ground water can be affected by land use activities above as surface water can seep into the aquifer.

Today Councillors approved a staff recommendation to speed-up a programme to replace those wells with deeper ones.

They also agreed that information should be prepared for residents, explaining the risks of providing water from shallow, unconfined bores and paying particular attention to those with special needs due to health, such as dialysis, or for fish tanks.

Council Head of Three Waters and Waste John Mackie said where possible water would be supplied from deep bores, although the more demand there was, the greater likelihood the Council would have to draw on the shallow wells.

“One thing we’d ask of people is to conserve water where they can, especially during summer. Fixing leaks and not watering gardens or lawns will reduce the likelihood we’ll have to use treated water from shallow bores.”

Most of the shallow, unconfined wells would be shut down by the end of March 2017.

As well as speeding up the replacement programme, the Council will increase its testing regime for E.Coli (testing is done daily in the northwest zone) and check wellheads for possible vulnerability to contamination.

Speeding up the well replacement programme is expected to cost about $480,000. It will be funded by bringing forward money from future budgets and deferring other less critical projects.

Canterbury District Health Board Medical Officer of Health Dr Ramon Pink said he supported the Council's decision to bring forward its plan to shut down the shallow wells by the end of March next year.

"I was also pleased to hear that in the interim the Council plans to prioritise using the deeper bores, further reducing the risk of contamination. Residents will need to make a concerted effort with water conservation measures over peak water usage periods, so that the shallow bores will not need to be utilised,'' Dr Pink said.

Canterbury DHB would continue to work closely with the Council to monitor the quality and safety of the current water supply. If there were any concerns about the level of risk to public health increasing, they would act swiftly to let people know.

“Northwest residents can be reassured by the clear results from the Council’s extensive water testing programme, which goes well beyond the requirements of the national Drinking Water Standards”, Dr Pink said. 

Learn more about Christchurch's water supply.