How to Clean a Sink Drain When You Suspect Drain Flies

Drain flies often breed in slimy organic film near drains. Addressing that buildup and any ongoing moisture issue is more useful than killing only the flying adults.

A safer cleaning approach

• Look for small, fuzzy, mothlike flies near the drain and confirm the likely source.
• Remove hair and accessible debris from a removable strainer using gloves and suitable tools.
• Scrub reachable drain walls and components as the fixture manufacturer permits.
• Use an appropriate mechanical drain brush or follow a labeled enzymatic cleaning product’s directions.
• Repair slow leaks or drainage problems that leave damp buildup behind.

Keep in mind

Never mix bleach with acids, ammonia or other drain cleaners; hazardous gases can form.

Frequently asked question

Can pouring boiling water down the sink fix it?

Not reliably. It may not remove all biofilm, and very hot water can be unsuitable for some plumbing components.