How to Get Rid of Sewer Flies

If you’ve noticed tiny, moth-like flies hanging around your sinks or showers, chances are you’re dealing with sewer flies. These pests, also known as drain flies, breed in the gunk and grime that collects in moist drains and plumbing fixtures. While they don’t bite, their presence can be more than just annoying—they often signal hidden buildup or plumbing problems. Left untreated, they multiply fast and may even spread bacteria around your home. 

Fortunately, getting rid of sewer flies is possible with a few targeted steps. In this blog, we’ll show you how to eliminate sewer flies at the source—and how Lickety-Split can help keep them gone for good.

What Are Sewer Flies?

Sewer flies—also called drain flies, moth flies, or filter flies—are tiny pests known for their fuzzy, moth-like appearance and erratic flying patterns. They’re usually gray or black, and only about 1/8 of an inch long. Despite their small size, they’re easy to spot once they start clustering around sinks, tubs, or floor drains.

These flies thrive in damp environments with organic material, making your home’s drains an ideal breeding ground. They lay their eggs in the slimy film that builds up inside pipes, and their larvae feed on that sludge until they’re ready to emerge as adults.

While sewer flies aren’t dangerous in the traditional sense, they can indicate a bigger problem in your plumbing system—like clogs, dirty traps, or standing water. And until you clear out their breeding source, they’ll just keep coming back.

Signs You Have Sewer Flies

You may not notice a sewer fly problem right away, but once they multiply, the signs become harder to ignore. Here’s what to look for:

Seeing Small, Moth-Like Flies Around Drains

The most obvious sign is spotting tiny flies hovering near sinks, bathtubs, or floor drains. They often rest on walls nearby and are most active in the evening.

Larvae or Slime in Drain Openings

Check inside the drain with a flashlight. If you see slimy buildup, dark sludge, or tiny worm-like larvae wiggling near the surface, that’s likely the breeding ground.

Persistent Drain Odors or Slow Drainage

Foul smells and slow-draining sinks often point to organic buildup—exactly what sewer flies feed and nest in. These plumbing issues usually go hand-in-hand with an infestation.

What Causes Sewer Flies?

Sewer flies are more than a nuisance—they’re a red flag that your drains may need some attention. Here are the most common causes behind an infestation:

Organic Buildup in Drains

Grease, soap scum, food particles, and other debris can collect inside your drains and create a perfect breeding environment for sewer flies. This sludge is where they lay eggs and where larvae thrive.

Standing Water or Moisture Issues

Drains that don’t fully empty—or those with constant moisture—are ideal for sewer flies. Leaks, slow drains, or faulty traps allow water to pool, giving flies a place to breed and feed.

Unused or Rarely Cleaned Drains

Basement floor drains, guest bathroom sinks, or laundry room tubs that aren’t used regularly can become breeding grounds. Without water flow or cleaning, bacteria and grime build up and invite flies in.

How to Get Rid of Sewer Flies

Getting rid of sewer flies requires a two-step approach: eliminate the breeding ground and kill the adult flies. Here’s how to do both effectively.

Clean the Drain Thoroughly

Start by scrubbing inside the drain using a long, stiff-bristled brush to remove slime and buildup. Follow that with a natural solution like boiling water, baking soda and vinegar, or a commercial enzyme drain cleaner. These options help break down organic material without damaging your pipes.

Kill Adult Flies

While you’re cleaning the source, use fly traps, sticky tape, or apple cider vinegar traps near affected drains to capture adult flies. Keep the area as dry as possible—sewer flies need moisture to breed, so reducing humidity makes your home less inviting.

Address Underlying Plumbing Issues

If the problem keeps returning, you may have a leak, clog, or damaged drain trap that needs professional repair. A licensed plumber can inspect the lines, clean hard-to-reach buildup, and ensure your plumbing is in top shape.

How to Prevent Sewer Flies from Coming Back

Once you’ve gotten rid of sewer flies, it’s important to take steps to keep them away for good. Prevention is all about consistent drain care and moisture control.

Run Water in Unused Drains Regularly

If you have a guest bathroom or basement drain that doesn’t get used often, run water through it weekly to prevent dry traps and stagnant water.

Clean Bathroom and Kitchen Drains Monthly

Use a natural cleaner or enzyme-based treatment to break down gunk before it builds up. Regular scrubbing can stop new breeding grounds from forming.

Use Enzyme Cleaners or Drain Treatments

These products are safe for your plumbing and effective at removing the organic material sewer flies love. Incorporate them into your cleaning routine.

Schedule Seasonal Drain Maintenance

A professional cleaning from Lickety-Split can help flush out buildup and identify early plumbing issues before they attract pests.

Flush Sewer Flies Away with Lickety-Split

Sewer flies may be small, but they’re a clear sign that your drains need attention. Whether it’s organic buildup, standing water, or plumbing issues, tackling the root cause is the only way to stop these pests for good. A quick fix might reduce the swarm—but without cleaning the source, they’ll be back before you know it.

Regular maintenance, proper drain care, and fast action can make all the difference. And when you need expert help to eliminate sewer flies and clean your drains thoroughly, we’re just a call away.

Contact Lickety-Split today for reliable drain cleaning services and sewer fly solutions. We’ll get your plumbing—and your home—back to fresh and fly-free in no time.