Have you ever seen those slow moving flies bumping around in the restroom and wonder what they are and where they came from? They’re drain flies and can live year-round in restrooms. Drain flies breed on polluted, shallow water or the scum that often collects around drains. They love drains that are full of stagnant water. The remedy is to simply pour water routinely down all drains, especially floor drains in commercial buildings. Hot water helps kill the larvae. A bleach and water solution can be used also but be careful. Some drain cleaners and bleach don’t mix. It’s a toxic combination. Make sure your cleaning/janitorial contractor flushes your drains regularly.