How to Reduce Drain Flies by Cleaning a Sink Drain

Small mothlike drain flies can breed in organic film on wet drain surfaces; physically removing buildup is usually more important than pouring in a scented product.

Practical steps

1. Identify whether the insects are fuzzy and lingering near a particular drain.
2. Remove accessible hair and sludge from the stopper or strainer.
3. Clean accessible drain surfaces with a suitable brush, following plumbing safety guidance.
4. Flush according to the drain and cleaner manufacturer instructions.
5. Investigate recurring leaks or blocked pipes if adults keep returning.

What explains the result?

Drain flies differ from fruit flies and fungus gnats. Their larvae live in the film that develops around persistently wet organic matter, so an adult trap addresses only the symptom.

What to avoid

Never mix bleach, ammonia, acids or drain cleaners; hazardous gases and burns can result.

Frequently asked question

Will boiling water alone eliminate drain flies?

It may rinse some residue, but physical cleaning and fixing moisture problems are more reliable, and boiling water can damage some plumbing.