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Q. We have an A.O. Smith 50 gallon electric hot water heater which is about 8 years old. We are on well and septic and have a water conditioning system. The piping is copper. In the last 6 months or so, the hot water has a "rotten egg" smell which is particularly noticeable when the hot water first starts to flow, then drops off with continued usage. I had been told that this might be a result of the anode deteriorating. I flush the water from the bottom of the tanks every 6 months or so, and there is usually a residue of a gray-white sandy material. If my memory serves me well, a few years ago you responded to an inquiry about the anode, however, I don't recall your answer. Will the sacrificial anode contribute to or cause the sulfur smell? Can the anode be removed without significant loss of tank life? Please advise.
A. The rule used to be if the water heater has an anode-- almost all do-- and the water stinks, pull it out. Removing it completely will reduce the smell and may eliminate it but it will certainly void any warranty left and may shorten the working life of the heater tank. I’ve known homeowners who have taken that route and struck the bargain of shorter water heater tank life in favor of hot water that doesn’t stink.
However, all wells in this area of which I’ve had any experience import some bacteria into the house. You can place a UVC sanitizer light on the well line and reduce that by 99.9% but most people don’t do that and the bacteria generally isn’t harmful to most humans. One of those strains of bugs that gets into the water heater is called sulfur-reducing bacteria (SRB) and lives in the tank giving off the very odor you describe.
A water heater provides a good environment for SRBs because of the sacrificial anode. The anode helps protect the water heater by corroding instead of the tank lining like the zincs used in boating and to protect wire crab traps. SRBs, it turns out, are nourished by electrons released from the anode as it corrodes.
There are two ways of getting rid of these bugs. You can put a sanitizing agent into the water heater tank itself for a one-time cleansing-- bleach-- or you can turn the thermostat of the water heater up to 140ºF. To do that you take the following step s. Step one is to turn off the electrical power to the water heater. It will be a 30-amp 220v breaker in your electrical panel box and should be listed. If you cannot find the right breaker then don’t go to steps two or three.
Step two is to remove the small covers on the side of the water heater tank to expose the rear of the heater elements. You may have to pull some insulation out to see them. Remember to put it back when you are done. Step three is to take a screwdriver and insert into the slotted screw at the rear of the element and turn it so the little arrow points to 140. Do it for both elements. Some water heaters only have one element so if you just have one don’t worry, just set that one. Make sure both element s are set to the same temperature then replace the covers on the tank side and turn the power back on. It should take a few days but the elevated temperature should kill the bacteria and eliminate the smell. Some professionals recommend setting the elem ents even higher to 160º for awhile then back down to 140º. If you do that be sure you warn everyone in the house about it.
Before 1990 or so all water heaters came out of the factory pre-set at 140ºF. I was told the original setting of 140º came from the need of water that hot for older automatic dishwashers to work well.
There are a whole bunch off nasty bugs that can’t survive in water 140ºF and above, like SRB. Legionella pneumophila bacterium is another one. One way you get Legionnaire’s disease is by taking a shower using water that has the bacteria in it and inhali ng droplets of infected water. It’s happened. It wouldn’t have if the setting was left at 140º. There are all sorts of plumbing devices that eliminate the potential of scalding and I recommend them.
Now, upping a water heater’s temperature to 140º and leaving it there is heresy to many for a number of commonly accepted reasons. The argument is that you don’t need water hotter than 120º and to a great extent that’s true. It greatly reduces the scald ing hazard which is why the heaters were turned down to 120º from the 140º factory setting pre-1990 or so. It was the lawyers that drove that change, not water heater designers or enviromentalists.
The lowered setting saves electricity because you are not storing water at a temperature that you are most likely to mix with cold water to use, rendering the whole idea of such hot water silly. It used to be that the manufacturers of dishwashers wanted 140º water but that need went away when they started incorporating a water heating feature into the washers themselves and the detergents got better.
Pulling the anode out of a water heater can be a lot more difficult than you might think depending upon the headroom you have above the tank. You turn off the water (and I turn the power off too, just to be sure), then open a hot water faucet to take the pressure off the tank and unscrew the bolt of the anode and pull it up and out. That’s easy if you have the room. Anodes don’t like to bend. The worst case is you have to empty the tank of water, unhook all connections-- wire and pipe-- and place the tank on its side to pull the anode out. That can be a big job for a do-it-yourselver and if you think you’ve got problems at home now, wait till you screw that job up and have to call a plumber to bail you out leaving the house without hot water for ho urs if not days until the pros show up. I never attempt a plumbing repair on a weekend. Murphy’s Law always awaits me.
Try the temperature trick first. It’s easier.