house indoor sewer smell

Hi all,

We have a finished basement in our house with a shower/bathroom, a sink, basement floor drain and washer/dryer. In the last five years, we have never had any sewer smell in the basement. We keep the sink/drain traps full with water, washer discharge pipe all taped up so no air escapes, and right everything seems to drain/flush ok.

But in the last few weeks we are getting this smell on and off, and lately it has been pretty bad. I checked the roof to see if the vent is clogged/iced over, but that's not the case. I checked the catch basin that's behind our house today (first time since the Chicago snow melted).

Here are pictures:

https://www.box.com/s/1jz4wz39uyiwxhgvjlei
https://www.box.com/s/w6540heli311pwa5v1tm

The water level has never been so low before, this is the first time that I am actually seeing the drain pipes.

Looks like there are two pipes, the one on the top (say 12 o'clock) is facing towards me. The other one (say 1 o'clock) is a lateral pipe, it seems. Although it looks like there is sediment in front of the second pipe I think it is kind of misleading, from where I saw the pipe did not look like it was blocked.

Is it normal that the water level is so low that these are visible? We are five people in the house so I'd assume there is going to be enough water flow with the three showers and bathrooms under use.

Also, do you think the smell is coming into our basement because there is no water and the trap(s) may be dry? If that's the case, filling the catch basin up with water may eliminate the issue?

Thanks in advance.

Does the floor drain have a trap and do you have another under the water tank.
Do you have natural gas?

The floor drain has a trap, and we have been filling it, too.... drain hole for the water heater leads to the French drain that leads to the sump / sump pump. I smelled the sump and it does not smell sewer at all. The smell comes more from the center of the basement, I think.

Yes we have natural gas and a furnace.

If it smells like a rotten egg smell, I would have the gas company come out and check your water heater and furnace. Natural gas smells like sewage also.

Thanks but I do not think it is gas. Will check it again, though...