Almost 120 well heads have been raised above ground since June 2018 under major efforts to future-proof Christchurch's drinking water network. (First published 2018)

Christchurch residents are still largely ignoring a call to conserve city water or risk restrictions or more chlorination.

The Christchurch City Council has asked householders and commercial water users to cut back to ease the pressure on the system and make vital well repairs easier to carry out.

As part of a five-month campaign that began in November, the council said it wanted collective water use across the city to be no higher than 140 million litres per day.

STACY SQUIRES/STUFF Christchurch locals filling containers with spring water last May instead of drinking chlorinated tap water.

However, an analysis by Stuff of water use over the Christmas-New Year holiday break shows residents are paying little heed to the council.

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With the exceptions of Christmas Day and New Year's Day, when total use fell just a few per cent below the 140m litre threshold, taps have been left running regardless.

Julian Matthews The city council has already warned watering restrictions might be necessary if residents fail to reduce water use while wells are repaired.

On December 29, the city used 183m litres of water – more than 30 per cent higher than the requested maximum.

Residents have already been warned that, without reductions, the council might have to start using those wells from which water would need to be chlorinated.

In March last year the council controversially began chlorinating Christchurch's water after testing showed damaged well heads risked contaminating water rising from the aquifers under the city.

STACY SQUIRES/STUFF Helen Beaumont, head of the Christchurch City Council's water supply improvement programme, and engineer George Chapman visit a well-head pumping station.

Watering restrictions may be another consequence of not enough buy-in from the public.

Christchurch mayor Lianne Dalziel has previously said the plea to conserve water was not because of any shortage – there has been plenty of rain – but to allow for speedy repairs.

On the council's website there are nine "Our Water Use" dials – one for the city as a whole and eight for each water zone.

STACY SQUIRES/STUFF Repairs are under way to wells below Christchurch, prompting city council calls to conserve water.

Each has three segments: green for average and "no restrictions necessary", yellow for heightened alert, and red for danger and "restrictions may apply".

According to the council's figures, Christchurch residents, from December 24 to January 1 inclusive, used a total of 1.394 billion litres of water – an average of 154,916 litres a day, or about 11 per cent higher than asked for.

During that nine-day period, water use in the central city zone was constantly in the yellow segment of above 55m litres a day.

On six days – December 24, 27, 28, 29, 30 and 31 – city zone use broke up into the danger red segment above 75m litres a day, peaking at 88.139m litres on the 29th, 17 per cent above the top of the yellow.

The council's website says that level of use means "we may need to impose water restrictions".

"When demand for water is high we can only supply so much through the network. The pumps, pipes and reservoirs can only deliver a certain amount of water at any one time. If people use too much there could be a pressure loss in the system, shortages or not enough to fight fires."

On December 30, residential water use across all eight zones pushed the limits.

Six zones – Ferrymead, Northwest, Parklands, Rawhiti, Riccarton and West – were in the orange segment. Central and Kainga-Brooklands were in the red.

The council was approached for comment but a spokeswoman said nobody was available to talk about it. Only emergencies or breaking news were being responded to.

It is unclear if the council has taken any action as a result of residents' high water use over the holiday period.

In November, Helen Beaumont, head of the council's water supply improvement programme, said there was a clear message for residents – use less if you don't want chlorine back in your water.

"The less water that's used, then the faster we can do the work."

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