We have a septic tank but have recently have a sewer smell by the washer (upstairs utility room). We have a low water level in our toilet in the main bathroom. We were told maybe it was a clogged vent, but looking down the vents as far as we can see; it dosen't appear so. We also have a 3/4 bath closer to the utility room with a shower we never use. Could it be a dry trap in there causing the smell? Is it unhealthy other than the smell to have this in our house? Annee

I had a similar problem and in my situation it was easy to fix. We also have our washer upstairs and underneath the washer is a catch-basin for potential overflow. The water in the drain trap evaporated and released a strong sewer smell. We simply put some water in this overflow drain and solved our problem. I hope your solution is as easy to fix!

Bobshank is correct. You gave it away when you said that the shower is never used. The trap, which stops sewer gas from coming up into the house, is replenished whenever the plumbing fixture is used, since the water going down the drain replenishes the trap. Not using the drain allows the water to evaporate, allowing the sewer gas (methane) through the drain and into the house.

As for the low water level in the toilet, assuming that it gets used, and that the water is not simply evaporating out of the bowl, the adjustment is inside of the tank. When you pull off the lid, you will notice a mark on the rear wall of the tank, indicating the water level. This is usually within an inch of the overflow pipe, in the center of the tank. There should also be a small tube which feeds water from the fill valve, on the left side of the tank, into the overflow pipe, where it goes through the rim of the bowl and fills the bowl to the proper level. If all is well with these, and there are no obstructions lodged in the toilet bowl trap or drain, and the vent stack is open to the sky (no dead squirrels in the stack), then the toilet should drain and fill properly.

Yes, methane gas is very unhealthy, and is also flamable. Fortunately, the solution to your problem is simple

There is an item called a trap primer that keeps a small amount of water supplied to these traps that have no regular water source to keep them from drying out.

I have a laundry room next to a restroom. I only use the toilet and sink but not the tub. When I enter my laundryroom it always smells stinky and Now since reading these comments maybe it is because I don't use the tub? Maybe dirty water is in the drain?

A trap primer is a small tube off one of the cold water feeds, which allows fresh water to enter a drain line, above the trap, in order to replenish a trap which doesn't get used. It is one remedy for the problem, and it does work. However, the cheapest remedy is to simply use the drain periodically, either by using the fixture which is emitting the odor, whether it is a tub, shower, sink, floor drain, or whatever, or by pouring a quart of water down the offending drain once a week.

I agree that your problem probably comes from a dried out trap below the washer. Upper-level laundry rooms usually have a floor drain under or near the washer to protect the levels below in the event of overflow. Unfortunately, these drains become open to the sewer lines if the water traps in them dry out, which they will do if not used or primed regularly. The best way to prevent this trap from drying out is to fill it with mineral oil (not water). It will not evaporate like water will but will still give way if the floor drain is needed in the event of an overflow. Simply pour a pint or so of mineral oil into the drain (you may have to move the washer aside or tilt it up to gain access to the drain below) and your problem should be solved. The same method can be used for the seldom-used shower. You'll need to replace the mineral oil if the shower ever is used, though.

If you find that it is not an empty trap, try having your septic tank pumped out. I had the same problem when using my washer and found that it was simply a tank overload. good luck.

Sorry to followup so late on this topic but...my finished basement shower is virtually never used and based on the previous posts I would bet the trap is dry, hence the lovely sewage smell we are now getting. 1. Will a dry trap cause the shower to leak as wekk as smell, should it be used in the future? 2. Should I call a plumber,, or will occaisionally running water through it solve the problem? 3. If instead of water I pour mineral oil into the drain (as suggested above), do I have to remember to remove the mineral oil before using the shower (and if so how)? Thanks all.