We have a terrible septic smell after long showers or if a toilet runs continuously. It does not matter if it is the shower or toilet is on the first floor or second floor, all create the same smell. The smell comes from the basement, not the room where the water is generated. There are no open caps/pipes and there are no dry traps. Seems to be worse in the winter but condition has been evident for years. Any suggestions where to start? We've called numerousl plumers thinking we need to smoke test for leaks but no one seems to know what that means.

Thank you in advance for any advise.

If the smell is coming from the basement, that's probably where the problem lies...

Here's a couple of questions for you: Are you on a septic field, or city sewer? Does the main line out go under the floor, or out through the foundation wall?

If you're on a city sewer line, call the city and ask for their help.

I would suggest a couple of possible causes for the odor.. By no means should you consider this a complete list! 1) There's a partial blockage in the main line, causing waste water to back up after heavy use. The backed up waste is seeping out somewhere, causing the smell. How long after running the water does the smell last? If it dissipates quickly, I'm thinking a vent problem.. If it lingers, then maybe it's liquid.

2) Are there any unused drains in the basement? Floor drains, a laundry sink that isn't used.. something like that? If there is, try pouring a gallon or so of soapy water down that drain and see if it helps... Sometimes the water in a drain trap evaporates, letting the sewer gasses escape.

If there is a partial clog (even if there isn't) it's a good idea to use some Roebic's Main Line Cleaner on your system. There are other brands too - make sure you get one with LIVE bacteria. Basically, the bacteria gets in there and eats all the old soap scum, grease, hair, paper bits, etc. It takes a few applications, but it does a lot of good.

I hope maybe some of this helps.. Sorry if it's a little rambling - been up for 38 hours with some of my own issues.

Good luck!