Smelly Shower Drain

I have a standalone non tub shower that routinely smells. There is never any standing water on the shower floor itself. I unscrewed the drain cleaned it out there was some hair and dirt. There then was a little bit of water below the drain so I poured some bleach in it and it seemed clean or just didn't smell.

After a day or so, the smell returned. Is there supposed to be water below the drain in the pipe and if so how much? Or do I have to pour Drano in there etc.

Thanks!!

 

Don't use Drano! Save your money. Yes, there must be water at the bottom of the drain in the P-Trap. It's the water that keeps the sewer gas from entering the room.

Do you use the shower every day or the odor returns after a few days of non use?
When the odor returns is there water at the bottom of the drain, just lower or about the same?
Is this a new install, or and old one where this problem just started?
Is the pipe PVC or iron?

For some reason the water level is dropping. Causes could be a few things, one is there is not enough venting and if a large volume of water drains, a suction is created behind the flowing water and it pulls some of the water out of the trap. Usually when there is little use of a sink or shower drain, the water can evaporate but this is probably not your problem. If this is on a slab the p-trap could be leaking into the ground. Just google "how does a p trap work" and you'll find plenty of information.

 

To answer your question:

The shower is used about twice a day. When the odor returns the water level seems to be at the same level.
It is not a new install, shower is about 5 years old. This problem has existed for at least 1 year. The pipe I believe is PVC. This shower is located on the 2nd level of our house.