How do I get ride of gnats in my basemnt?I had a new water system put in and there is a gap between the wall and the lip of the water system. They told me that gap was for any leakage in the wall and that it it would drain down so it would not get on the floor. I plugged up the that side of the wall with the round form strip. Also could the gnats be coming coming through the discharge pipe that goes outside. Right now the pipe lays in grass and I do have water. Its been about four months laying there.