Residents of Baildon in West Yorkshire have been told to boil their tap water after it was found to contain higher than usual levels of a type of bacteria.
Yorkshire Water issued a boil order on Wednesday evening covering around 600 properties in the BD17 5 postcode area following the discovery of coliform bacteria in the supply.
It said water should be boiled until further notice for drinking, cleaning teeth and preparing foods which will be eaten uncooked, such as salads.
A spokesperson said: "We'd like to remind customers that boiling water provides sufficient protection; however, we appreciate that can be inconvenient and have delivered bottled water to any customer on our priority services register. "
They added: "We are working hard to get things back to normal as quickly as possible and would like to thank everyone affected for their patience."
Coliform is a family of bacteria containing E. coli.
Tap water can still be used for washing, bathing, toilet flushing, washing dishes and laundry, Yorkshire Water said.
A full list of streets affected can be found on the Yorkshire Water website.
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