South West Water staff were out at work on New Year’s Day to repair the main sewage pumping station in Newquay.
Flows from the station have been diverted into tankers and out to sea through the emergency sea outfall at Towan Head.
The water company first became aware of the problem at the Gannel Sewage Pumping Station at 11.30pm on New Year's Eve and worked through the night to contain the problem and minimise the risk of pollution in the town centre.
Waste Water Operations Manager Mike Galligan said the company had been working night and day to fix the issue as quickly as possible.
The Environmental Health department of Cornwall Council has been informed. They will assess the issue and make a decision whether to put up signs at affected beaches. Beaches most likely to be affected are Crantock and Fistral Beach.