Fast Plumbing Answers: Get Rid of Drain Flies

There’s a slimy layer of bacteria, biofilm and organic sludge attracting drain flies to your sinks. These gross little gnats show up every time you wash dishes or visit the bathroom sink. You don’t just want to kill them- you want them gone forever.

Don’t worry- we’ll answer all your questions in 3 minutes or less.

Drain flies are attracted to the organic material in your drain pipe. If you kill them, they’ll just come back. You need to eliminate standing water, organic blockages and biofilm in your kitchen and bathroom sink drains to get them out of your home.

Our Master Plumbers explain why drain flies keep coming back, and why bacterial and enzyme drain cleaners are the best way to get rid of them for good.

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Quick Answer: Pro Drain Cleaning and Non-Toxic Maintenance

Don’t want to read the whole article? Here’s the quick solution to drain flies in your sinks:

Start with a professional drain cleaning from a licensed plumber with specific knowledge of residential drainage plumbing systems. That includes your drain, drain pipes and the sewer line underneath your yard.

Follow that up with a bacteria or enzyme drain cleaner. These products actively eat away at organic material in your drains for up to 30 days between uses. The pesky little flies won’t have anything to eat, and your sink drain won’t be an attractive place to lay eggs anymore.

“Use a bacterial cleaner like Endure or BioOne instead of the harsh chemicals,” says our Responsible Master Plumber Steven Smith (RMP-43457). “You need a cleaner that keeps getting rid of the grease and hair mats that gnats love long after we clean your drains.”

Why Your Sink Has a Drain Fly Infestation

The gnats that gather around your sink drains want the organic buildup that’s accumulated in your drain pipes. No matter how clean you are, you can’t keep every ounce of bacon fat or strand of hair out of your sink forever.

“You’re not dirty if you have drain gnats,” Steven explains. “It’s a part of life. You eat food, brush your hair, use the garbage disposal- they’re going to show up from time to time.”

The Four Drains Where Sewer Flies Show Up Most Often

You probably noticed these pesky drain flies in one of these four locations:

1. Kitchen sink and bathroom sink drains
2. Shower and bathtub drains
3. Laundry room floor drains
4. Basement floor drain areas

The Tape Trick to Find Your Drain Fly Problem Area

Dry the area around your sink, floor or shower drain. Place a piece of tape sticky-side down over 90% of the drain, leaving a small opening for airflow.

In the morning, check the underside of the tape. If you see small, fuzzy sewer gnats stuck to the tape, you found your infested drain.

Why Are Sink Flies So Hard to Kill?

Drain flies show up for two reasons: to eat, and to lay eggs. That’s precisely why they’re so hard to kill: by the time you get rid of the original adult drain fly population, the drain fly larvae hatch and take their place.

“It feels like you’re fighting an army,” Steven says. “They’re so small, but they frustrate our customers so much.”

These DIY Remedies for Drain Flies Fall Short

Boiling water and bleach are popular “DIY sink fly killers”, but they rarely work as intended. And as we've covered in other articles about slow clogged drains, baking soda and vinegar is an “all show, no sizzle” solution that does nothing to kill adult flies or their eggs.

Boiling Water: The moment hot water hits your drain pipe, it starts to cool. You'll see “phantom results”- it kills a few adult flies on contact. But it doesn't resolve the sludge and organic buildup in the pipe that attracted them in the first place.

Bleach: “Pouring bleach down the sink is never a good idea,” Steven warns. “It runs by too fast to kill the flies or the eggs, and it corrodes the drain pipe on the way. You still have flies, but now you have plumbing damage."

Baking Soda and Vinegar: The fizz is a great show, but that's it. It doesn't break down the fats, oil and grease in your sink drain. And it doesn't reliably kill sink flies or their eggs, either. A few might drown in the solution, but they would have in plain water.

Chemical drain cleaners don’t work on sink flies. They flush past too quickly without clearing the entire organic blockage or killing the entire population. All they do is hurt your plumbing.

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The 3-Step Plan to Kill Drain Flies For Good

A little bit of elbow grease (DIY scrubbing), a professional drain cleaning appointment and ongoing use of enzyme or bacterial drain cleaner gets rid of existing sink flies, kills their larvae and eggs, and keeps them out of your home.

Here’s how:

1. Scrub thoroughly. Use a stiff wire brush to scrub the inside of your affected drain pipes. Don’t worry about the adult population- you’re getting a head start on eliminating the eggs and larvae that cause recurring issues. 
2. Schedule drain cleaning. Hire a licensed plumbing service that utilizes non-toxic drain cleaning products. This ensures that your plumber’s intensive cleaning clears the organic matter from your drains and kills the flies without damaging or corroding your drain pipes. This is particularly important for older PVC and cast iron materials.
3. Monthly bacterial or enzyme drain cleaner use. Use Endure, BioOne or a highly-rated enzymatic or bacterial cleaner every 30 days. These products turn organic buildup in drains into water and carbon dioxide. No corrosion, no toxic chemicals in your house, and nothing left for the flies to feast on or lay eggs in.

Tiny flies in your DFW sink? Call Mother 24/7 for drain cleaning service, plus a free bottle of Endure drain cleaner to keep the flies away forever.

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