Re: Sewer smell from shower drain
There are several possibilities that create a foul smell, but you should first prove that it is the drain and not the hot water that is causing the odour.
Sometimes the anode rod has a negative reaction to your local water and this causes a sulphur like odour.
You can test this by running the shower with cold water only.
If you don't get the odour with cold water only …. then try to smell the hot water at another outlet and see if it has odour.
It’s more likely to show up while taking a shower since this is when the most hot water is being used for an extended period…… aside from the enclosed washing machine or dishwasher.
There's only two ways you would get sewer odour from the shower drain.
One is if the trap seal were lowered or reduced, allowing sewer gas to escape.
The other is if there were back pressure down the vent causing a "blowback" of sewer gas through the trap.
But you would likely hear "gurgling" or "bubbling" noise in the drain when the toilet was flushed.
The reason for a trap seal is to contain sewer gas.
The inside surface of bathroom sink, tub and shower drains can also be a huge source of odors.
Kitchen sinks frequently have similar odor problems.
The odour may be from rotting hair mixed with soap and other things creating a bio-film of slimy goo. Bacteria that is breeding and multiplying in the bio-film is coating the vertical tailpiece between the fixture trap and the actual drain outlet in the fixture.
For the most part ….. all sinks have a piece of pipe called a tailpiece that extends from the bottom of the sink into the top of the p trap which is constantly exposed to the air in your bathroom.
All of the bacteria, dirt, grime, mold, etc. pass through this pipe on its way to the sewer or septic system …. often some is left behind. Over time a thick layer of slime starts to collect on the inside surface of this pipe allowing mold and bacteria which can begin to grow and some produce noxious odors.
The reason you smell this when you first use a fixture …… the motion of the water first hitting the bio-film releases some of the bacteria molecules into the air
Remove the drain strainer in the shower and you will see a layer of slimy goo on the side of the pipe leading down to the trap. Clean off this goo with a 50/50 mix of chlorine bleach and water and a stiff bottle brush works nicely.
Do the same in the sink. You will have to remove the sink stopper to gain access to the vertical tailpiece.
Bathroom sinks can also develop odors in the overflow part of the actual sink. The overflow is a little hole at the top of the sink that connects to the bottom of the sink. It is also susceptible to slime buildup.
It is tougher to clean but using a turkey baster filled with a 50/50 mix of chlorine bleach and water to kill the bacteria does work. You have to squirt the solution into the overflow tube vigorously several times and let it sit to try to coat the entire lining of the tube. Try to use a small bottle brush to clean this passageway.
The same can be said about the overflow located on a tub.
Just some thoughts.
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