Work to flush out water mains around Lynn will begin next week.
Anglian Water will be undertaking the overnight works over a period of almost three weeks.
In a letter sent to businesses and residents, which details which streets will be affected and when, the company said customers may see flushed water running into the drains.
But it added: “This work is essential to make sure that we can maintain the quality of your drinking water supply.”
The work will start this Monday, October 26, from 9pm and will take place on Mondays to Thursdays until November 12 from 9 or 10pm until 6am each day.
Customers are advised to fill a kettle or suitable container with drinking water before the work starts in their areas and not to use washing machines and dishwashers while the work takes place.
The company also says that if water supplies remain cloudy or discoloured once the work is complete, residents should run their kitchen cold water tap until the water runs clear.