Rotten egg smell in the hot water? Start with the water heater

One thing first. If the smell is in the air around the water heater or anywhere in the house, not in water from a tap, and your home has gas or propane, it may be a gas leak. Do not flip switches or light anything. Get everyone outside, then call your gas company or propane supplier, or the fire department, from outside.

If the smell comes from a drain you rarely use, run water into it for a minute to refill the trap. A dry trap lets sewer gas into the house.

If the smell is in the water itself, you are not the only one. UGA Extension counts sulfur odor among the things Georgia well owners run into, and it usually has a plain cause. One quick check tells you where to look.

First, smell the cold water

Run the cold tap, then the hot. If only the hot water smells, the water heater is the likely source. UGA Extension explains that the magnesium rod inside many water heaters, there to slow corrosion in the tank, can turn the natural sulfates in groundwater into hydrogen sulfide gas. That gas is the rotten egg smell. If the rod is the only source, only the hot water smells.

The sulfate is natural. The U.S. Geological Survey lists it among the most common dissolved minerals in water from the Upper Floridan aquifer.

If the cold water smells too, the water heater is not the only source, and the smell is more likely coming from the water itself.

If it is only the hot water

UGA Extension's fix is to replace the magnesium rod with one made of aluminum or zinc, preferably by a licensed plumber, and to use only an aluminum rod if the water heater is set above 150 degrees.

Do not just pull the rod out and leave it out. Penn State Extension points out that running a heater without one can increase corrosion, shorten the heater's life and will likely void the manufacturer's warranty.

A water softener can make it worse. UGA Extension says softened water dissolves the magnesium rod faster, and the dissolved magnesium can feed the bacteria that make the gas.

If the cold water smells too

On a well, the usual cause is bacteria that live underground, where there is no oxygen, and turn sulfur compounds into hydrogen sulfide. UGA Extension says that in well water it is usually just a nuisance.

When bacteria in the well are the cause, UGA Extension says shock chlorinating the well can clear it up. If two tries do not work, continuous chlorination or another treatment may be needed.

In rare cases, the smell can mean sewage is reaching a shallow or poorly built well near a septic drainfield. If there is any chance of that, UGA Extension advises testing for coliform bacteria and nitrate.

Test before you buy anything

Before you spend money on a filter or treatment system, get the water tested. UGA Extension's advice is that the right system depends on how much hydrogen sulfide or sulfate is actually in the water, and it recommends testing a private well every year anyway.

• In Liberty County, the UGA Extension office at 100 Main Street in Hinesville offers well water tests. You pick up the kit at the office.
• In Long County, the Extension office on West Academy Street in Ludowici is a good first call to ask about testing.
• In Tattnall and Evans counties, the county health department will test a private well for bacteria at the owner's request.

If it turns out to be the water heater, give us a call. We repair and replace water heaters, tank type and tankless, gas or electric.

Sources: UGA Extension, Hydrogen Sulfide and Sulfate; UGA Extension, Removal of Hydrogen Sulfide and Sulfate; Penn State Extension; USGS Ground Water Atlas; UGA Extension, well water questions; UGA Extension, Liberty County; Southeast Health District.