A water company has said it is "increasingly confident" tap water in thousands of Surrey homes is not contaminated after finding E.coli at one of its treatment works.
People living in Oxted, Redhill, Horley, Biggin Hill, Tonbridge, Limpsfield, Godstone and Sevenoaks are being advised to boil their drinking water after the problem was uncovered on Thursday.
SES Water said one sample from its Westwood Water Treatment Works tested positive for the potentially deadly bacteria on Thursday, prompting the "boil notice" for 443 postcodes - about 6,500 properties.
But after multiple tests, it is thought the water will be cleared for drinking soon.
On Friday evening, Tom Kelly, SES' wholesale director said: "I am pleased to say that through our investigations over the last 24 hours, involving sampling and analysis of water quality throughout the area covered by the precautionary boil notice, there is no indication of contaminated water leaving the treatment works.
"We are awaiting final confirmation of this with a third set of tests within the next 24 hours but at this stage, based on the latest sampling results, we are increasingly confident we can lift the precautionary boil notice tomorrow."
He apologised for the "inconvenience and concern" but said it was "the right thing to do, based on the information available at the time"
The NHS says E.coli does not usually cause any problems while it is living in the gut, but that if the bacteria contaminates areas of vulnerability such as wounds, infection can occur.
Those considered most at risk if they do become infected include the elderly, people with urinary catheterisation and those suffering dehydration, prostate problems, gall bladder or kidney stones, open wounds or ulcers, or with long-term conditions such as COPD, bronchitis or diabetes.
While most cases are mild, some strains of E. coli can cause severe symptoms and even life-threatening complications, which can lead to kidney failure and death.
Officials reminded people in the affected areas to let the boiled water cool before using it for drinking, preparing food or cleaning their teeth and added the same process should be followed for water given to pets.
"Boiled water can be kept in the fridge, and should be covered and used within 24 hours," a spokesperson said.