We recently installed an internal drain system in our basement to alleviate flooding during the rainy season. Recently afterward, we started noticing a sewage-like (or perhaps pipe-like) smell in the basement during the late afternoon and evening hours. It's very unpleasant. Has anyone experienced this problem?

More info: Last winter I had the foundation drains roto-rooted during a storm (due to flooding), and the rooter pulled up foul sewage-smelling material... in the vicinity of the now-smelly basement. That same drain pipes now literally burps-up foul smelling liquid during the rainy season on occasion. Again, it smells very bad like sewage.

The thing is, our sewage pipe is located at the other end of the house and drains away from the house (through a neighbor's yard, unfortunately). I have a theory that sewage is creeping into our footing drains. Could that be? My house was built in '65.

Well, right off the bat, I would just like to point out that just because it smells horrible, it doesn't have to be sewage: I recently cleand 15 years' worth of rotting leaves from someone's roof gutters, and they smelled horrendous, not to mention that my hands still stank after washing them with antibacterial soap several times.

I'm not saying it isn't sewage. I'm just saying it doesn't have to be. My point is that any form of decaying organic matter can stink like heck, even if it's not bodily waste.