John Powers, West Tisbury health agent, got the all-clear Tuesday from the state Department of Environmental Protection. A water ban begun September 23, and affecting the water supply for the town hall, the Grange Hall, and the old library, has been lifted, he said.
Because the cause of the contamination has not been determined, Mr. Powers has scheduled an inspection today of the water system. He also plans to continue to monitor water quality over the next four to five weeks, he said.
The news was expected. On Monday, water samples taken from downtown buildings on September 24, 25, and 26 produced clean results. Mr. Powers notified the Department of Environmental Protection that afternoon.
The West Tisbury board of health warned September 23 of contamination of the water supply for the town hall, the Grange Hall, and the old library. The warning instructed the public not to drink the water in those buildings until repeat test samples were free of contamination.
Coliform bacteria and E. coli bacteria were found on September 20 in a routine sample collected from the water well that supplies the buildings, according to the notice. Fecal coliform and E. coli are bacteria whose presence indicates that the water may be contaminated with human or animal wastes, the notice said.
In a telephone interview September 23, Mr. Powers said that additional water samples subsequently collected also showed the presence of bacteria. The town began to chlorinate the system on September 23.
After 24 hours, the water system was flushed, and additional repeat test samples taken. Water samples must test clean from bacteria three to four days in a row before the Department of Environmental Protection will lift the ban on using the water.
During the ban, all of the water fountains and faucets fed by the well were shut off in the buildings and grounds. Toilets still functioned.
For more information, contact the board of health at 508-696-0105.