How to : How to Get Rid of Drain Flies

Use an enzyme gel to break down organic residue in your pipes. Enzyme cleaners are designed to target buildup leftover from a manual cleaning and prevent future blockages. First, clean your drain with a metal pipe brush—run some warm water down your drain and then dislodge any buildup by inserting the brush as deep as it will go. Then, pour the cleaner down the drain and let it sit for several hours (check the instructions on the bottle for details). Then run some water down the drain to flush it out.^[6]

Cleanse your pipes with a traditional drain cleaner. Regular commercial cleaners are great for removing buildup that causes clogs and attracts drain flies. First, clean your drain with a metal pipe brush by running warm water down your drain and dislodging any buildup by inserting the brush as deep as it will go. Then, use your cleaner according to the instructions. Read the warnings carefully—some are unsafe to use more than once, and some are specifically designed for bathroom drains.^[7]

Try chemical sprays and bug repellents for severe infestations. Some pest control killers can be used to kill flies and larvae in your drain—check the label to make sure drain flies are listed. These repellents have harsh chemicals in them, so read the instructions and warnings carefully to confirm they’re safe for indoor use and won’t damage your pipes.^[8]

Clean your drains regularly to prevent an infestation. This is the best way to keep drain flies from moving into your bathroom or kitchen sinks. Drain or wipe up any stagnant water near all of the drains in your home. If you have a drain that’s prone to flies, pour boiling water or a cleaner down there 1-2 times per week for maintenance.^[10]

Clean up standing water in and around your home. Drain flies can infiltrate more than just your bathroom or kitchen sinks—all they need is stagnant water and something to eat. Keep an eye on places like sump pumps, potted plants, garbage disposals, dirty mops, buckets of water, condensation pans, or moisture underneath loose tiles. Remove any trash and food sources that can attract drain flies around your home. If you see standing water, clean it up immediately.^[11]

Look for drain flies on your walls as a sign of infestation. Drain flies are (ironically) bad at flying, so you’ll most likely catch them resting on the walls or ceiling very close to their source. The pipe or drain nearest to where you spotted the flies is most likely their breeding ground. Even if you only spot a single fly, it’s best to thoroughly clean the suspected drain with a pipe brush or drain cleaner as soon as you can (they reproduce very quickly).^[12]

Drain flies are small, gray, and fuzzy. They look like gnats, fruit flies, or moths and are also known as moth flies or sink flies because of their appearance and preferred habitat. Unlike these animals though, they have weak wing muscles and hop and jump around more than they fly. They can range from 2.5 millimetres (0.098 in) to 4.5 millimetres (0.18 in) long and have dense, hair-like scales on their wings.^[13]

Drain flies thrive in stagnant water and organic matter. They can eat almost anything, including food bits, slime buildup, sewage, or even just bacteria. This makes kitchen and bathroom drains, basements, sewers, septic tanks, and even wet soil a paradise for them, especially in humid environments.^[14]

Drain flies are not harmful. Drain flies don’t bite and don’t carry bacteria that are dangerous to humans. They don’t pose any health risks unless they emerge in massive numbers, which only happens in septic systems or sewers and not inside people’s homes. They don’t cause any physical damage to your pipes or indoor plants either.^[15]