Shower Drain's Rotten-Egg Odor Is No Yolk

By Jeanne Huber
Special to The Washington Post
Thursday, March 15, 2007

Q We have a terrible smell, like rotten eggs, coming out of our shower drain. On the advice of a plumber, we've been using a product that clears gunk with enzymes and bacteria, but the smell is still there. Our house is only four years old and the smell has just recently appeared. What can we do about it?

ASmells are often worst in a shower because the heat and spray circulates gases and vapors around the room.

There's a slim chance that the smell could indicate that sewage is somehow seeping into your piping. Rule that out by getting your water tested.

If you are on a private well, also have the sulfate level checked because this is the more likely cause of the smell. If you are on a public water system, call your water company and ask what minerals are in the supply.

If your water contains sulfates (picked up from mineral deposits in the ground), it could be turning into hydrogen sulfide gas, which smells like rotten eggs, in your water heater. Many water heaters have a magnesium rod to prevent corrosion, and when sulfate-laden water comes in contact with magnesium it results in a chemical reaction that forms the smelly gas. If this is the problem, you can eliminate the smell by replacing the anti-corrosion rod with one made of aluminum or other material, available at plumbing supply houses.

You can probably do this yourself. Just shut off the incoming cold water, remove the nut at the top of the tank, and pull out the old rod. Insert the new one, retighten the nut, and reopen the cold-water valve. As with all plumbing repairs you tackle yourself, do the work when plumbing stores are open in case something goes wrong and you need additional parts.

The smells could also be occurring because of bacterial growth in your water. It probably isn't a health issue, but to deal with the annoyance, call a company that supplies and services water softeners and water filters and ask for advice. The specific remedy depends on what other minerals are in the water.

Our bathroom sink drains slowly. I removed the stopper and can see that gunk has built up over the years in the pipe leading directly from the sink, before the trap. What is the easiest way to clean out this stuff?

This is a situation where the enzyme cleaners mentioned in the previous question would help.

Years ago, the first step in clearing a sluggish drain was dumping a big pot of nearly boiling water down the drain. Don't do that, though, unless you're certain your house's drainage system is made entirely of metal. PVC plastic, which is much more common today, softens at 140 degrees.

If the blockage is just in the first few inches of the drain, you might be able to clear it by removing the stopper and using tweezers, a thin bottle brush, or a bent wire to pull out hair and other clumpy matter. If that doesn't work, try taking apart the trap under the sink and cleaning out the plumbing from there. Put a bucket or pan under the trap as you remove it to catch the debris. Keep the parts in order and take them to a plumbing-supply store or home center and buy replacement gaskets to use when you put it all back together.

If you don't want to get your hands dirty or fear you won't be able to get the plumbing back together, try using an enzyme drain cleaner. One brand is Bio-Clean. It contains enzymes and bacteria that digest hair and other organic materials but don't damage piping, as lye-based drain cleaners can. The only problem is that you'll probably need to spend more than $40, since this product is sold in a two-pound size, good for about 100 drain cleanings. Depending on prices in your area, calling in a plumber might be easier and not that much more expensive.

Is there something in your house or apartment that's clogged, cracked, broken or bedeviling? We'd like to help. Send your questions to Jeanne Huber at .

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