Help!!! We moved into our 5-year-old house in July 2001. Last March (2002) we started getting a very bad sewage smell in the house during heavy rains. Subsequently, we looked in our crawlspace and discovered -lots- of standing water. A foundation drainage system and sump pump solved this problem. For a while, it seemed to solve our smell problem as well. Not quite. The problem is back. We get more than a couple of inches of rain, and the smell comes back! It seems to come from the A/C vents running through the crawlspace. The crawlspace itself smells of sewage. No water under the house now, that I can see, though.
The toilets, tubs, and sinks all drain fine, and no dry traps.
Any ideas?