Water that is giving off a distinctive rotten egg smell in Massachusetts is most likely contaminated with hydrogen sulfide. Hydrogen sulfide does not usually pose immediate health problems at the levels it is found in domestic drinking supplies, however, it is certainly an inconvenience to one’s sense of smell.
WHAT IS HYDROGEN SULFIDE?
Hydrogen sulfide is a colorless gas that can exist naturally in groundwater. Sulfur-reducing bacteria present in groundwater use sulfur as an energy source to chemically change sulfates to hydrogen sulfide. The bacteria use sulfur from decaying plants and other organic matter in oxygen-deficient environments. They can occur in deep or shallow wells, and reside in plumbing systems. The distinctive rotten egg smell is undeniable!
Hydrogen sulfide shows up in other ways too. The magnesium rod used in water heaters for corrosion control can chemically reduce sulfates to hydrogen sulfide, thus resulting in the same rotten egg smell when turning on the hot water.
Hydrogen sulfide, if present, will vary by well due to varying geology. It is the most common in shales and sandstones. The occurrence of hydrogen sulfide gas has been correlated to groundwater with low pH and groundwater with high levels of iron and/or manganese (common minerals in New England). It also may be associated with hydrocarbons and peat formations.
For a detailed paper on Hydrogen Sulfide, see the link at Hydrogen Sulfide Paper.
REMOVAL OF HYDROGEN SULFIDE
There are various methods to remove hydrogen sulfide. They should be chosen based on the level, the amount of water being treated, the levels of iron and manganese, and the water’s pH among other factors. Methods to reduce or remove hydrogen sulfide include activated carbon filtration, shock chlorination, ion exchange, manganese greensand filtration, oxidation, oxidizing filtration, ozone treatment, and water heater modification. Your selected water treatment professional will know the proper system for your particular situation. If the rotten egg smell persists, you know the correct solution has not been determined.