PROVIDENCE (AP) — About 25,000 customers of the Kent County Water Authority have been advised to boil their water until at least Thursday after tests found E. coli bacteria contamination in a storage tank.Water authority customers in Cranston, Coventry, Warwick, West Warwick, East Greenwich and some in North Kingstown and West Greenwich should boil their water vigorously for at least one minute before drinking it, cooking with it or brushing their teeth with it. The advisory also affects residents in the Potowomut section of Warwick, which purchases water from the authority.Customers are advised to not bathe infants and young children in the water, because they may accidentally swallow some.E. coli was found Friday during routine testing. The state Health Department said the source of the contamination is under investigation.The authority said Monday that samples are being collected from throughout the system to determine whether the contamination has spread. The Providence Journal reported that the results from the first day of three days of mandatory tests came back negative for E. coli.Health Director Michael Fine told WPRO-AM on Monday the boil-water order will be in place until at least Thursday.“It could go later depending on what the daily testing shows,” he said.Fine said the department doesn’t know of anyone who has become sick because of the contamination. The federal Centers for Disease Control and Prevention says most strains of E. coli are harmless, but some can cause illness, including diarrhea, urinary tract infections, respiratory problems and pneumonia.Timothy Brown, the authority’s general manager and chief engineer, told The Journal this is the first time in more than 25 years there has been an E. coli contamination in the drinking water supply.