Eight months after town health officials first detected a contaminated plume running beneath Edgartown Meadows subdivision, they are turning their attention to installing clean drinking water in the neighborhood instead of pinpointing the cause.

"This has dragged on for more than half a year. It's obviously more of a long-term problem," said Matthew Poole, Edgartown health agent.

"The most important thing is for people to have safe drinking water regardless of whether the source is septic systems or the golf club or something we haven't even considered," he added.

A new round of private well tests in an Edgartown neighborhood this week intensified the mystery for Island officials working to pinpoint the source of groundwater contamination spreading through the West Tisbury Road subdivision.

"It's too much of a puzzle, too many unknowns at this point," said Matthew Poole, Edgartown health agent, noting that now 20 per cent of the homes tested have water unsafe for drinking.