I have researched drowning fleas. There is a lot of good data at Can dish soap really be used to kill ticks and fleas? the summary there suggests if you wash fleas away in the yard, your pet well get them back tomorrow. But if you wash them down the drain they are gone forever.

There are multiple online reports of "drowning fleas" and killing them with soapy water. After looking for the science there does not seem to be much support for these fatal claims. There is little doubt that giving your pet a soapy bath in the tub will help remove the fleas, they may even appear dead. But in all likelihood these fleas are just waiting to dry out and be revived, hopefully in the city sewer. If you bath your pet in the yard, and than let the dry pet in the yard again the next day the clean pet and clean revived fleas will likely reunite. Soapy water is more likely to facilitate removal of the comatose flea from the pet and carry it down the drain. So it is reasonable to have noticeable decrease in the flea population after a bath. But excessive bathing has it's own risks and given the life cycle of a flea soapy baths alone are unlikely to be a final solution.

I believe some insects, like spiders if flushed or washed down the drain will often climb back up into the home.

Does the same hold true for fleas? Does flushed = "Gone" or "On a short trip, be right back"?

  • You can always make sure they're dead, and as you groom your pet after a bath, press these fleas between your nails(I've seen that regular shampoo makes them lethargic) and then just toss them in a container with a weak mixture of water and bleach, then pour that mixture down the drain.
    – Just Do It
    Jun 18, 2016 at 14:25

4 Answers 4


In the US, modern plumbing has a trap. A small amount of water stays in the trap to prevent sewer gases from entering the building.

If a flea is washed down the drain but doesn't get pushed all of the way into the sewer, it will hang out in this water pool, and thus, will never get dried out to revive.

Sometimes the traps of infrequently used drains will dry out, but the flea will die in 24 hours of submersion. The trap will not dry out in 24 hours.

  • @James Jenkins, I think zaralynda has it covered. I just wanted to add that the soap itself probably doesn't kill the insects unless it's an insecticidal pet soap, which I would use if I suspected my pets had them. What the soap does is break the surface tension of the water, so that instead of sitting on top of it and eventually working their way to the edge and climbing out, they sink and drown.
    – Dalton
    Jun 20, 2016 at 13:18

I know it’s probably the least of the concerns right now, but you aren’t supposed to put any type of those hard core bug killers (bengal, Raid, etc.) into any type of drain or anywhere that will have it going into the water system. It’s very toxic and not meant to be introduced to water systems.

Not trying to nag, and I do sympathize with your issue, I recently found a bunch of fleas on me after given my cats flea treatments for the season. I don’t know if they jumped off of them and onto me or what, but because I didn’t initially realize they were fleas, I panicked and bought a kit to treat lice in the hair, it wasn’t till after using the de-licer kit that I realized it was fleas, but it did work nonetheless, and I haven’t had any troubles since.

Just a suggestion, I know they aren’t in your hair but maybe that de-licer stuff could help in some way. Good luck.

  • The products you mention are NOT appropriate for using on people or animals. So I am confused on how/why you would be putting them down the drain for this question. Maybe you are suggesting that people should not, put these products down the drain after washing the pet/person? Jul 14, 2020 at 12:16

Yes!!! I just tackled a flea problem in my house and while I was dealing with the problem I kept pulling fleas off my socks and washing them down my bathroom sink drain. A few times I noticed a flea or two hanging out in my sink so I thought maybe they weren’t going down the drain, so I stayed and watched them to make sure. A while later, there was a flea in that sink again. I started thinking maybe the water was attracting them to the bathroom sink. But then I wondered if they were somehow hopping out and that’s how I got here. Now that I think about it, I know this drain has a partial clog because my sink empties slowly and belches up a bubble before fully emptying. I bet they’re getting caught in whatever nasty debris is hanging out in the drain. They dry out and revive when the water stops and hop back out a little stunned but no worse for wear. They can probably even hold onto the sides if they’re coated with enough gunk. I’m guessing that running scalding hot water for a few minutes ought to do the trick. They are determined survivors. I give them that.


I don't care what all the internet posts say about fleas not being in drains. I have them. I am a biologist. I know a flea. These are not snow fleas or gnats or drain flies! I have the flea bites! I recently bathed my two dogs that were covered in fleas in our guest bathtub. I treat my dogs monthly with Advantage and have not had a flea problem on dogs OR house or yard in years! However, they were covered in fleas. Maybe I got a bad batch?? I don't know. After the baths I cleaned the tub as usual - been doing this for 25 years in same tub. One night I took a bath in there. There were fleas on me! I cleaned real good - didn't see any. I noticed this again soon after. Now when I go in that bathroom, the white tub has fleas -yes, real fleas that bite, same ones on dogs - all on the bottom only of the tub. I have sprayed with Bengal, I have bleached. I have poured salt down the drain. I have let bleach water stand in tub overnight. Next day, more fleas on bottom of tub. They are not on the sides or around the edge. If I reach in to swipe with a paper towel thinking they are dead, they jump on me and bite. The only place they can be coming from is the drain. I am thinking from when I bathed the flea ridden dogs and let their fleas go down the drain. I have set off two excellent flea foggers in the past week in that room alone. (Can't think of a way to fog the inside of a drain. I did spray Bengal down the drain.) Right now I have a tub full of dead fleas. I am not going to clean it. I am going to let that fog residue just sit. I am sick of it. Just don't discount the reports of fleas in drains!!

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