I just had the whole sewer line replaced about 5 weeks ago. We had the camera test done and discovered that the whole line was cracked and opened. We noticed drain flies and gnats all over the house. I am still seeing flies and gnats now that the work is completed. My plumber said that it could take a while for this problem to go away. How long will it be before this problem is resolved?

The difficulty in getting rid of these bothersome little flies is that they can continue to lay eggs in the organic residue left over from the broken pipes. If only the broken sections were replaced, there could still be soap scum and other organic residue in the old pipes that are still good. An enzyme based drain cleaner can get rid of that residue and get them out of the pipes completely.

If the bad pipes were under the house and left spillage in the soil, the flies could come in around the pipes or electric conduits or even the clothes dryer vent. A layer of lime will help break down the spillage faster and eliminate that as a breeding site as well as reduce odors from organic decay.