How to Get Rid of Drain Flies

Give these nasty pests the boot before they take over the kitchen, and keep them away for good

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June 13, 2022
drain fly clogmia albipunctata

Drain flies are about the same size as fruit flies — 1/6 to 1/5 inches long — but have wings that give them a mothlike appearance.

Photo by: Shutterstock/Macronatura.es

Shutterstock/Macronatura.es

Drain flies are about the same size as fruit flies — 1/6 to 1/5 inches long — but have wings that give them a mothlike appearance.

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There are few things as annoying as flies in your house. They buzz around your food and your stuff, spreading germs and grossness. One of the most common flies that gets into your house is the drain fly.

These irritating insects congregate around your sinks, showers and bathtubs — especially if the sink or drain isn’t used daily. Here’s what you need to know about these household pests and how to get rid of them.

What Are Drain Flies?

Drain flies are also called moth flies, sink flies or filter flies. Their fuzzy, dark-colored bodies are about the same size as fruit flies (1/6 to 1/5 inches long), but they have wings that appear large for their bodies that give them a mothlike appearance. They range in color from pale gray to black, and they don’t fly as aggressively or well as fruit flies. You’ll notice they hop from place to place, instead of buzzing you Top Gun-style, like fruit flies do. These common pests are short-lived, only on Earth for three weeks or so, but they can breed and make up to 300 more flies in just 48 hours. This means drain flies can go from a couple of flies to a full-on infestation, fast.

Why Are Drain Flies in My House?

Drain flies are attracted to small amounts of stagnant water they find in plumbing pipes, sinks or other drainage areas. The flies feed on tiny amounts of bacteria, algae and sewage, so you can find them gathering around kitchen and outdoor sinks, shower and bathtub drains, basement sinks, sewers and septic tanks. Drain flies love sinks and drains that don’t get used much, so if you have a guest bathroom or a shop sink in a garage, drain flies are more likely to find the pool of dirty water they need to feed and breed. They come into your house from the outdoors when they smell water and they set up shop in a drainpipe.

The presence of drain flies doesn’t mean you have a dirty house or mucky pipes. Drain flies can pop into a clean kitchen while you are away on vacation. All they need is a little undisturbed water in the crook of a drainpipe and a few days with no human disturbance.

Fruit Flies Will Get in Your Drain, Too.

Drain flies aren’t the only pests who will set a colony in your sink. Fruit flies will, too, attracted to rotting food that can get caught in your drain when you do dishes. They will lay their eggs in that decaying food that makes a gunky buildup in your drainpipe.

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How Do I Get Rid of Drain Flies and Fruit Flies?

You're going to need to clean out the infested drain, whether the pests in question are fruit flies or drain flies. The good news is you can do it yourself. Here are some ways to get rid of those pesty flies.

1. First, clean your sink and drain with your regular cleaning solution.
Use a tube brush to scrub around and inside the drain. Rinse the cleaning solution down the sink and drain with hot water.

2. Once you have cleaned the drain, do one of the following:

  • Make a natural cleaning/fly killer mixture. Mix together 1/2 cup of salt, 1/2 cup baking soda and 1 cup of vinegar. Pour the mixture down the drain. Let sit overnight, then flush the drain with hot water in the morning. This should kill all flies and the organic material they’ve been feeding on.

  • Bring in the big guns. If your homemade cleaning solution can’t clear the flies and gunk out of your drain, use a store-bought drain cleaner like Bio-Clean. It uses a combo of natural bacteria and enzymes to digest the organic waste (like grease and food particles) those drain flies are eating. Other commercial products that can wipe out drain flies are Green Gobbler and Natural Armor Drain Fly Killer.

3. If you’re still seeing drain flies, make an organic fly trap.
Pour apple cider vinegar into a bowl and cover it with plastic wrap. Punch holes in the plastic wrap and leave the bowl near the sink where you are seeing the flies. Flies will go in those holes to get the vinegar and get trapped. They aren’t real smart. They’ll drown in the vinegar. Another way to make an organic trap: Seal off the drain with duct tape for several consecutive nights. The drain flies will stick to the tape and die.

DO NOT pour boiling water in your pipes.

There are some home advice sites that tell you to get rid of drain flies by pouring a pot of boiling water down your drain repeatedly. If you have PVC pipes, boiling water ­— which is 212 degrees — can damage them. Don't do that. Cracked PVC pipes are a bigger problem than drain flies.

How Do I Prevent Drain Flies From Returning?

Flush out your pipes regularly with water or cleaning solution. If you have a drain that goes days or weeks without use, close it with a stopper to keep the drain flies out.

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