Fluoride - There is for practical purposes no natural fluoride (<0.1 ppm) in the Town's potable water and at present, the Town does not add fluoride.
Chlorine - The Town sanitizes its potable water with the addition of gaseous chlorine which is maintained at a concentration required by the State Health Department.
Iron - The iron concentration in the Town's potable water is <0.1 ppm. This concentration is maintained by contacting the iron at the Town's mainland wells with chlorine, allowing it to react during its transfer to the Island and removing it by sand filtration before distribution.
Odor - Odor in the Town's well water is eliminated by contracting the water at the wells with chlorine and allowing a long reaction time as it travels to the Island. Odor similar to "rotten eggs" from sulfides may at times be noticed in hot water systems especially if not frequently used.
Hardness - With a hardness concentration of approximately 150 ppm, the Town's potable water has been termed "moderately hard" by the State Health Department. The effect of hardness in water is to require slightly more soap to form a lather and detergent to wash dishes and clothes. Harder water also may cause deposits in hot water heaters, coffee makers and refrigerator ice makers.
Annual Water Quality Report 2009