Improvement work at the Oamaru Water Treatment Plant this spring will halve its capacity.
The Waitaki District Council is asking those on the Oamaru water supply to conserve water while the work is under way to avoid water restrictions.
The council issued a statement yesterday asking those on the supply to hand-water gardens, spend less time in the shower, only run full loads in dishwashers and washing machines, not wash cars and ensure leaks are fixed - "including running toilets, dripping taps and leaking pipes".
Council water services and waste manager Martin Pacey said the installation of four new membrane racks at the treatment plant over the next few weeks would be the final work to upgrade treatment membranes, which has been ongoing throughout the year.
The council was waiting for parts to arrive and work would begin when they did.
"This will require us to halve treatment capacity at the water treatment plant for just a few days," Mr Pacey said.
"We're heading into the summer period when water use traditionally ramps up with the warmer days, so it's something we need to consider and prepare people for now.
"Depending on how things go, there is a possibility we'll need to issue a conserve or restrict water notice while the membranes are being installed. However, we're hoping to avoid this, if possible, by encouraging the community to get behind this important upgrade and to reduce their water use now so we can keep our water reservoir topped up."
The work was part of a larger project to improve the supply's resilience to adverse weather events and increased demand in the future, which was to include the installation of an additional 8700cu m treated water reservoir at the treatment plant site in 2020.
A report to the council's assets committee over winter stated the water treatment plant "can only produce slightly more than demand with little margin for outages or faults".
Mr Pacey said at the time the new membranes would increase the plant's capacity by 30%.
In December, the council had issued water restrictions, warning that about 15,000 people on the Oamaru supply could run out of treated water after sustained heavy rain made the water entering the Oamaru treatment plant three times dirtier than it had ever been.
The Oamaru supply serves users from Oamaru to Moeraki.
