Dehumidifier was source of 'dirt' or mold smell
I am writing as a warning for people who might make the same mistake we did regarding hooking up the drainage of their dehumidifier to a basement drain pipe (I bet most people know this, but we didn't). We redid our basement 3 or so years ago and bought a sears dehumidifier. On his own initiative, our contractor hooked up our dehumidifier to a drainage pipe that feeds into our cesspool. About a year ago I started noticing a "dirt" smell. I had a lot of theories for the source of the smell but ruled them out one by one. I had a plumber come in and he couldn't find any leak or moisture anywhere. Finally a second plumber came in and identitied the problem as the dehumidifier -- it was blowing nasty pipe air into our basement (you couldn't really smell bad air while it was working)! We we tossed the sears humidifier and bought another that just drains into a sink. The smell went away. I can't believe I was so stupid!