Water samples taken Monday in Oak Bluffs were found clean, raising hopes that a boil-water order issued by the state could be lifted by the end of the week.

The order was issued by the Massachusetts Department of Environmental Protection last Friday after coliform bacteria was found in the public water supply.

Water samples from 40 different sites on Monday were flown to a private water testing firm in Sandwich. The town must record three consecutive days of uncontaminated water samples before the state order can be lifted.

Town administrator Michael Dutton said Wednesday he was optimistic the boil-water order could be lifted by Thursday afternoon.

“Monday’s results passed and we just received work that Tuesday’s results are looking good . . . although we’re waiting for definitive word from the state,” Mr. Dutton said.

Until the order is lifted the town will continue to hand out free bottled water at the town library on Pacific avenue. The water distribution is open from 8:30 a.m. to 6 p.m.; a police officer will be at the library after hours to hand out water if necessary.

The town has handed out approximately 275,000 gallons of water to town residents at an estimated cost of about $30,000, Mr. Dutton said.