Normally our water has no detectable odor, however some customers may notice that after returning from a trip, or after replacing their water heater, the hot water has a sulfur smell, a bit like rotten eggs.

Newer water heaters have set the thermostat lower than was typical in the past, and more frequently use magnesium anodes with no zinc. These two factors have increased the prevelance of this issue.

The cause of this smell is a harmless bacterium that feeds on sulfate and produces hydrogen sulfide gas.  There are several steps that can be taken to reduce or eliminate the presence of this bacteria in your hot water tank.

  1. Turn up your water heater to 160F degrees or higher for several days to kill the bacteria, then flush your tank.
  2. Replace the anode with one that contains zinc, which will help to control the bacteria.
  3. Add 2 pints per 40 gallons of 3% Hydrogen peroxide to the tank, let it sit for several hours, then flush your tank.
  4. If you haven’t flushed your water heater in several years, now is a great time to do so.


The links below provide additional information.


Fact sheet about color, taste, and odor from Washington DOH.