Sometimes during a home inspection the water will smell like rotten eggs and that is an unpleasant situation. It can also be unnerving to a prospective buyer. This issue is most common in well systems; not so much in public water in this part of the country. The smell is hydrogen sulfide gas which is produced by anaerobic bacteria in the water and it normally originates in the water heater. An easy way to check is to run just cold water and then just hot and see when the water smells.
In water heaters there is something called a sacrificial anode that is made of magnesium or aluminum and that is what the water reacts with to make the hydrogen sulfide. Its purpose is to reduce the risk of corrosion in the water heater, so you can’t just remove it altogether. But sometimes replacing the sacrificial anode will eliminate (or reduce) the problem. Another possible solution is to remove the anode rod and pour a quart of peroxide or chlorine bleach into the water heater (peroxide is safer).
It’s one thing to find smelly water during a home inspection, but this problem became personal when my hot water started smelling bad. I have a 16 year old high efficiency gas water heater and I know better than to try replacing the anode rod on something that old. Fortunately, I couldn’t even find the anode rod so that possibility was eliminated. So, I tried the simplest solution. My hot water temperature was about 125 degrees F; that’s good to prevent scalding and plenty hot for a shower, but it is not high enough to kill the bacteria. So, I simply turned up the temperature to about 145 degrees which is high enough to kill the bacteria. It worked! Of course, the risk of scalding is higher now but I can always install a tempering valve which mixes a little cold water with the hot to knock the temperature back down. It’s nice when something simple and free works.
That’s all for now from the Helpful Home Inspector! Happy home-owning.