If you smell sulfur when you turn on a tap, the water is probably contaminated with hydrogen sulfide. While its smell may be its most offensive characteristic, this compound can cause nausea and tearing of the eyes at low concentrations, loss of smell at higher concentrations and death at very high concentrations, so it's nothing to take lightly. It's a byproduct of bacterial metabolic processes, and it could be coming from your well, a storage tank or the water heater.
Determine Where the Odors are Coming From
Sulfur odors may be present throughout the house, or you may notice them only at particular fixtures.
The presence of sulfur odors at every fixture in the house -- including the toilet tanks -- indicates a source of hydrogen sulfide contaminating either the water source or a holding tank that supplies the entire house.
- If you have a well, the water could be passing through a sulfur source, or it could be contaminated by other chemicals that produce hydrogen sulfide as a byproduct -- for example, nitrogen from agricultural sources.
- If a test of the well water reveals it to be free of odors, then suspect contamination in the holding tank. It's probably a buildup of non-pathogenic bacteria that are metabolizing the smelly gas.
- If only the hot water smells, the odor-causing bacteria are probably in the hot water tank.
- Smells coming from a particular part of the house, or a single fixture, usually indicate bacteria in the pipes. A common cause of these smells is a "dead-leg" run of pipes, which is one that has been capped off and is no longer used, but which nevertheless contains pressurized water.
- If you have a water softener, and the water from outdoor spigots is odor-free, the water softener is probably contaminated.
What to Do
If you have a whole-house problem, you may need to install a filtration system between the well or the water tank and the house -- it's usually best to install it as close to the house as possible.
- One of the most common and effective filtration systems consists of a chlorine feeder and an active-carbon filter. Chlorine oxidizes hydrogen sulfide gas to produce small, insoluble particles, and the filter removes these from the water.
- Aeration is another whole-house option. Water is sprayed into a ventilated tank, and oxygen in the air oxidizes the hydrogen sulfide gas. By itself, aeration may not remove the odors from highly contaminated water -- the addition of chlorine or another oxidizing agent, such as hydrogen peroxide, potassium permanganate or ozone, may be necessary.
For other problems:
- Removing dead-leg plumbing will solve odor problems affecting a single fixture or a group of fixtures.
- If you have traced the smells to a water softener, replace the filter.
- If the smells are coming from the water heater, shock chlorinating the tank should solve the problem. This entails draining the tank of sediment and, as the name suggests, disinfecting the heater with bleach.