Drain flies are a constant reminder that your bathroom drains are clogged. As soon as you take away their habitat, they get the hint and head off. The first step to getting rid of drain flies is locating the culprit. The oil separation method is perfect for this. Fill the inside of a few plastic cups with cooking oil and place them over any drains in your bathroom. When the drain flies come out, they get stuck in the oil separator. The cup with the most specimens determines the likely breeding site.
After that, the next phase is cleaning up. Remove any rotting organic matter by scrubbing the drain thoroughly. Loosen the dirt in the pipes with a drain cleaner or long brush and pour hot water down the drain to flush everything out. To disinfect the drain, make a natural cleaning solution using 1/2 cup baking soda, 1/2 cup salt, and 1 cup vinegar and pour it down the drain. This not only kills germs, but also dissolves any remaining residue. Leave it overnight to allow it to work, then rinse again with hot water.