Drain Flies: What They Are, Why You Have Them, and How to Get Rid of Them
- Mazzer

- Nov 25, 2025
- 1 min read
If you've ever walked into your kitchen or bathroom and noticed tiny flying insects hovering around the sink or shower drain, you're not alone. These little insects are called drain flies, and while they're harmless, they're definitely annoying. The good news is they can be eliminated once you know what's causing them.
What are Drain Flies?
Drain flies (also known as sewer gnats or moth flies) are small, fuzzy-looking insects about the size of a sesame seed. They love moisture, organic buildup, and slow-moving drains, making your plumbing a perfect home for those annoying flies.
Why Might You have Drain Flies?
Drain flies show up for a few common reasons:
Organic gunk in drains- Soap scum, grease, hair, and food scraps create buildup where flies lay eggs.
Rarely used drains- Stagnant water allows bacteria to grow, attracting drain flies.
Sewer line backups- Excess moisture or blockages can lead to breeding areas
Leaky pipes or damp areas - Any moisture source can become a breeding ground for them.
How to Tell if They're Coming From Your Drain
Here's a quick test:
Place a piece of tape sticky-side down over the drain overnight. If you see small flies stuck to it the next day, you've found the source.
When to call a Plumber
If the flies keep appearing or you find a strong sewage smell, it may indicate:
A cracked drain pipe
A broken trap
A sewer line issue
Hidden moisture behind walls or under floors
A plumber can inspect the system, clear clogged drains, repair leaks, and eliminate drain flies at their source.





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