Temporary water restrictions have been put in place for residents connected to the Oamaru supply while routine maintenance is carried out at the water treatment plant.
The Oamaru supply extends to Kakanui, Enfield and Weston.
Waitaki District Council contracts engineer Michael Goldingham said the maintenance included replacing filtration membranes for the first time since the treatment plant was commissioned in 2007.
While the work was being done, the amount of water able to be treated by the plant would be halved.
''We are asking people not to water their lawns and gardens and generally conserve water use from this Wednesday for 10 days,'' Mr Goldingham said.
''Careful watering of vegetable gardens will be OK during this period.''
The new membranes had the capacity to clean and filter 25% more water and were expected to last 10 years as opposed to seven years, saving $300,000 in replacement costs and $100,000 each year in operating costs.
Half the filtration membranes would be replaced now, and the rest in a ''few months' time''.
''We will let the public know when stage two is about to take place,'' he said.
