Discoloured water has been running from the city's urban supply since mid-December, the council says most likely due to a non-toxic, microscopic algae coming from its secondary source at Opihi.
Timaru District Council's drainage and water manager Grant Hall said work to increase the level of natural filtration by the river bed at will begin today, prior to the water reaching the intake, which is hoped to reduce the amount of algae coming into the system.
"All our water safety tests to date and those from independent testing laboratories show that the water is safe to drink and we're continuing to do extra water sampling until this situation is resolved," he said.
He said a test filtration plant for the water to pass through prior to treatment will be installed next week and the council is sourcing water from other networks to reduce the amount it takes from Opihi.
But for the measures to work effectively, residents needed to cut down on their water usage, Hall said.
"This is why from today Timaru Urban Water Supply will move to Level 3 Water Restrictions and a residential sprinkler ban.
"This will help support our efforts to resolve the discolouration issue, while ensuring we have enough supply to last through summer.
"Timaru City currently uses 21 million litres of water a day, we can only take 17 million litres a day from Pareora, and therefore we need to minimise the amount we have to supplement from the Opihi by reducing the water demand."
A sprinkler ban will be in force for all Timaru City residents - they can use a single hand held hose or micro jet system for one hour between 6pm and 8am but are not allowed to water their lawns.
Residents are also being asked to take shorter showers and only running their washing machines and dishwashers when they are full.
Hall said the council was taking the issue incredibly seriously.
"Most council staff live and work in Timaru, so we are both sharing the issue that the community is facing and understand the concerns about how long this is taking to resolve."
Water tankers have been organised for residents seeking an alternative drinking water source.
They are located at:
- Domain Avenue (outside the Botanic Gardens)
- Caroline Bay
- Aorangi Park