we have one shower in the house. (I had the cesspools checked and the
cesspool guy said they're not the problem)
It doesn't smell until you start the shower then this acrid smell comes
out of the drain that's pretty awful then it goes away after about a
The cesspool company said maybe it's a venting problem. My plumber said
it couldn't be something about the trap and how it's situated vis a vis
the vent( I didn't understand)
the plumber suggested pouring bleach down the drain that there was some
stuff in there. It didn't help! The trap and the piping under the
shower is new PVC.
Any ideas. I think it is a venting problem but the plumber doesn't want
to get his A## over here. and my guess is worth nothing when it comes
Thanks for any help
Remove the drain cover and look down with a bright light.
Can you see the water in the trap?
Yes? Then the trap is working and "trapping" sewer gases.
Flush the toilet while watching water in the trap.
Does the water remain relatively still? Doesn't get sucked out?
OK? Then it's not a venting issue.
Usually shower drain odors are caused by mold/mildew growth
on soap scum which is located *above* the trap inlet. Hot water
from showering releases noxious gases from the molds.
The fix in this case is a thorough scrubbing (toothbrush) with
a bleach solution to get rid of the scum. Just dumping bleach
down the drain won't get rid of it.
I had a similar problem a while back and was offered the same options for a
cure. However in my case, it turned out to be water leaking into the floor
around the drain and rotting the material underneath. Consider this if all
else fails. I had to remove and replace the floor and re-tile.
Another possibility is that it's hydrogen sulfide. It may not actually be
from the drain, but from the water itself. This has as characteristic
"rotten egg" smell that could be described as acrid.
If the problem comes from the water heater, it will typically appear when
the water is first turned on, and then go away after about a minute. It's
caused when sulfates in the water react with hydrogen in the water, and the
anode rod in the water heater can contribute to the problem. It can be more
prevalent if you have a water softener. Logically, it would happen with all
tap water, but since shower water has heat that forces the gas into the air
in a relatively enclosed place surrounded by the moisture that holds it,
it's often noticeable in the shower only.
The trap is still a sensible first place to look. If looking at the trap
gets you nowhere, then figure out if this odor comes from hot water only or
cold water too, if it's possible to do that in your shower. If you find
that it happens only when hot water is running, then your water heater may
need flushing, and the magnesium anode rod may need to be replaced with an
If this is the problem, be sure to read up on flushing water heaters before
you actually do it.
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