Why won't drain flies go away after pest control?
Drain flies survive standard treatments and professional pest control because they breed deep inside the slime layer of pipes where surface sprays cannot reach. This leaves homeowners stuck in a multi-year cycle of temporary fixes that fail to stop the bugs from coming back days later.
What the numbers show
Counted from the threads quoted below. How we count
- Most of it landed at once — the busiest month was September 2026, with 12 people.
- This comes up 30.0× more often in r/Pestcontrol than across the site as a whole.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Using bio foam in sink and shower drainsDid this help you?
- 2Pouring baking soda, vinegar, and boiling hot water down drainsDid this help you?
- 3Applying bleach down the sinkDid this help you?
- 4Using Zevo or dynatrap trapsDid this help you?
- 5Using boiling water and green goblin down drainsDid this help you?
- 6Pouring vinegarDid this help you?
- 7Placing Zevo light traps in every roomDid this help you?
- 8Applying weather sealant tape around windows and doorsDid this help you?
- 9Changing out the kitchen sink P trapDid this help you?
- 10Dumping bleach, drano, and gnat killer down the drains nightlyDid this help you?
- 11Using light trapsDid this help you?
- 12Using apple cider vinegar trapsDid this help you?
- 13Removing potential attractantsDid this help you?
- 14Hiring professional pest control to treat the home multiple timesDid this help you?
- 15Searching for hidden smells or sources of the fliesDid this help you?
- 16Pouring boiling water and vinegar down the drainDid this help you?
- 17Using drain cleaner or specialized drain fly treatments like Green GobblerDid this help you?
- 18Placing yellow sticky traps or tape above the sink and in potted plantsDid this help you?
- 19Thoroughly rinsing unrefrigerated produce upon returning from the grocery storeDid this help you?
- 20Using Zevo plug-in traps near the entry pointDid this help you?
- 21pouring boiling water and bleach down drains multiple times a dayDid this help you?
- 22making traps out of vinegar, sugar, and dish soapDid this help you?
- 23using a blue light with a sticky trapDid this help you?
- 24covering up and hiding all foodDid this help you?
- 25wiping down counters constantlyDid this help you?
- 26Using boiling hot water and soapDid this help you?
- 27Pouring Drano into the sink and sealing the stopper shut for a periodDid this help you?
- 28Running boiling water down every drain for multiple days in a rowDid this help you?
- 29Checking plumbing and sewer lines for cracksDid this help you?
- 30dumping apple cider vinegar down drains and covering overnightDid this help you?
- 31running kitchen drain degreaser down the sinkDid this help you?
- 32mixing up a strong citric acid solution and dumping it in the drains overnightDid this help you?
- 33boiling a pot of water and dumping it down the sinkDid this help you?
- 34repotting indoor plants in different soil or compostDid this help you?
- 35adding a simple water trap close to the tubDid this help you?
- 36pouring a vinegar and baking soda solution down the drainDid this help you?
- 37using multiple rounds of boiling waterDid this help you?
- 38covering the drains when not in useDid this help you?
- 39using a foaming bio drain cleaner overnight to reach crevicesDid this help you?
- 40Pouring bleach down the sink each nightDid this help you?
- 41Setting apple cider vinegar and soap trapsDid this help you?
- 42Vacuuming up dead bugs from windows and wallsDid this help you?
- 43Checking cabinets for rotten produce and washing all trash cansDid this help you?
- 44Taking the trap off the sink and cleaning it out completelyDid this help you?
- 45Running ice and cleaner through the garbage disposalDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“Basement bathroom. We’ve dealt with them for a few years, but they were always so mild I never explored much intervention.”source ↗
“They are terrorizing me and my toddler and we have a new baby and I’m just going through it please help me on how to get rid of these”source ↗
“Hello, we recently moved to Southwest Florida and have had drain flies constantly getting into the front door.”source ↗
“I have a Zevo plug-in right inside the door and I am having to change the refills constantly.”source ↗
“Please help! I can't keep fighting to keep them out of the house. It's driving me nuts and they're winning.”source ↗
“I will start it by saying I am so sorry for this novel but I am genuinely losing it with these flies”source ↗
“3 days after pest control and my remedies, they’re still coming in.”source ↗
“I put a red cup with oil over my suspected drain producing drain flies and this morning I woke up to what looked like both drain flies and worms or something. Wtf nightmare fuel. How tf do I kill this shit.”source ↗
“I’ve tried light traps, I’ve tried apple cider vinegar, they’re not falling for either of those. I’ve removed anything at all they could be attracted to, yet they’re still sticking around.”source ↗
“They crawl a lot I’ve never seen gnats crawl”source ↗
“I’ve lived in my northeast home for two years and have bottle flies/blow flies in my home everyday from may-September arranging from a few to over a dozen depending on heat/sunshine.”source ↗
“I’ve had my home treated three times this summer which doesn’t seem to do anything.”source ↗
“It seems I’ve tried every solution and nothing keeps them out.”source ↗
“I haven’t been able to get control of the situation as the house is vacant most the time.”source ↗
“I need help getting rid of drain flies and getting rid of them right away. For weeks I’ve been struggling to get rid of them.”source ↗
“Every single day multiple times a day I’m putting boiling and bleach down my drains.”source ↗
“I need all the unhinged advice I can get on how to get rid of them because I’m so sick of them being in my house.”source ↗
“I had some drain flies start appearing at my kitchen sink for about a week. I did a vinegar and baking soda solution as well as multiple rounds of boiling water before and after. I covered the drains after the final round of boiling water. The problem now is that they are almost everywhere in the apartment.”source ↗
“i had a similar nightmare and the only thing that actually stopped them was a foaming bio drain cleaner left in there overnight, gotta get it in every little crevice”source ↗
“Dealing with a bout of drain flies for a few months. Scrubbed the drain and used a liquid enzyme killer nightly.”source ↗
“I have these gnats I believe are coming from the disposal side of my sink. There is that rubber stopper but I can’t take it out to clean/scrub it.”source ↗
“I’ve used boiling hot water and soap but it doesn’t seem to do it.”source ↗
“my family wakes up every morning to a bunch of flies (dead and alive) in and around the sink. there’s also some pink/reddish ones that fly around our faces. how do we get rid of them??”source ↗
“I had this problem when I was living in Kansas. Once a month, I would heat a kettle of boiling water, put baking soda in all the drains, followed by vinegar, then the kettle of boiling water.”source ↗
“Desperate for some help to deal with what we’re told are drain flies from our kitchen sink.”source ↗
“Came home to them in every room, on the windows and light sources - way more live than dead. One bathroom pretty much unusable.”source ↗
“It’s now Friday and we have been sucking up dead ones and spraying live ones every hour!”source ↗
“We’ve had a fruit fly and gnat problem for the last 6 weeks.”source ↗
“We kill around 50 a day and there’s more the next day.”source ↗
“I changed out the kitchen sink P trap. We dump bleach, drano, gnat killer down the drains nightly”source ↗
“It’s eating up a lot of my day and has become a 2nd job of ours. Can’t even enjoy a meal without them crash landing the plates.”source ↗
“Having issues with smell and fruit flies.”source ↗
Where this came up
People with this problem also raised
- 44How to get rid of tiny flying bugs coming out of wooden furniture
- 16Why do restaurant fly lights and cleaning fail to stop flies?
- 8Why does the same bug spray stop working after a while?
- 2Insects exploding everywhere after dethatching the lawn
- 3How do I stop a cricket chirping inside my wall?
- 28Why won't house ants go away no matter what I spray?