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Yes, Rats Can Swim Up Your Toilet. And It Gets Worse Than That.

They eat our food. They furnish their nests with our detritus. They chew through our sheet metal, our lead pipes and our concrete. They outsmart us at every turn. They are our shadow, our enemy, our next door neighbor.    —”Rat City!Spy magazine, 1988

“You have to think like the rat,” my new friend Gregg told me. At the time, we were pushing Gregg’s homemade rat detector through a small hole in my basement ceiling. He had bought an endoscope camera online—the kind a doctor uses to hunt for polyps in one’s nether regions—and attached it to a bent wire coat hanger. The camera’s images would be displayed on his laptop.

Gregg became obsessed with rats when they took over his girlfriend Anne’s house, across the street from mine. Having tracked and conquered her rats, he was eager to bring his rat-buster skills and tools to my infestation. Gregg showed up on a Sunday afternoon with the endoscope and a two-gallon bleach sprayer and explained my role: Simply turn the endoscope’s light up or down on his command as he threaded the coat hanger through ceilings and walls.

In the ceiling space above the basement bathroom, we hit the mother lode: towering piles of little black rat turds appeared on the laptop screen. “Here’s your nest,” Gregg proclaimed, our first small victory in what had been a long, losing battle. As I wrote in May, I had already suffered an invasion of live rats, followed by stinking dead rats and a Flymageddon of bottle flies and flesh flies that hatched out of their carcasses.

I had learned a few things about rats by this point: They are creatures of habit. They establish trackways through a house, following the same paths each day: in, out, to food, to nest. And they can, in fact, rise up from the sewers.

VIDEO: WATCH OUT! A rat’s super swimming ability and flexibility enable it to make its way easily from the city streets to your toilet. See how they do it.

This last point became central to my investigation. When my husband, Jay, cut out a section of the bathroom ceiling where Gregg’s endoscope had led us, we found that our rat nest was centered around an old sewer drain pipe that, unbeknownst to us, had been cut but never capped during the removal of an upstairs toilet. Dark oily smudges marked the rim where rats had climbed up from the sewers and dropped into my basement ceiling space.

Upon further research, I found that not only is it pretty easy for a rat to climb up a three-inch toilet drain pipe (most of the time there’s not even water in it), but I live in a part of D.C. with a combined sewer system, so the storm drains on the street and the pipes from the toilets run to the same place. A combined sewer is one big, happy, Rat Central Station. 

Having figured out how our rats were getting in, and assuming that any remaining rats would have been scared away by our noisy labors and hole-poking, Jay capped the pipe, and we congratulated ourselves on a mystery solved.

Maybe you read my last post, and you can see where this is going.

One With the Rats

Rats’ superpowers are near-mythical: They can swim for three days. They can fit through holes the size of a quarter. They’ve even been said to have no solid bones, just cartilage (definitely false, and I can’t confirm whether they can collapse their ribcages). I looked to science for the truth. But I was surprised by the dearth of studies on the Norway rat—the common city rat, Rattus norvegicus—in the wild (the wild in this case being any city on Earth). Despite our long human history with lab rats, we know very little about the lives of the rats in our homes.

In fact, as veterinary scientist Chelsea Himsworth told me, “We probably know more about the ecology of polar bears than we do about rats.” Himsworth is studying how rats spread disease in cities as part of the Vancouver Rat Project.

“The interesting thing about Norway rats is they don’t exist in the wild,” Himsworth said. Their migrations—through Asia, over continents and across oceans—are our migrations. They’ve been in contact with humans for so long that they not only live with us, they depend on us almost entirely for food.  

They don’t stray far from our homes. One of the most important findings of the Vancouver Rat Project has been that rats form highly stable family groups or colonies, block by block in a city. And when people break up rat families, say by indiscriminate trapping or poisoning, the remaining rats are forced to move—and that’s when they tend to spread disease.

Sewer Rats

I was, of course, trying not to be indiscriminate at all. I wanted to kill them all—the whole rat family.

I told this to Robert Corrigan, who was described to me as the “rat king of New York City.” He seems okay with the title. Corrigan has spent his career fighting rats up and down the Eastern Seaboard, which—with its dense population, waterways, and old pipes—is pretty much rat heaven.

Corrigan said he agreed with Gregg in part: To wipe out an infestation you have to think like a rat. “But I also think it’s not difficult to out-think a rat,” he said. Unlike many animals, a rat must have both food and water every single day to survive. No skipping meals.


“If it doesn’t have food and water, it goes into this kind of ‘crazy mode,'” Corrigan said. Rats have a very low tolerance for hunger—so to get rid of them simply ask where they’re getting food and eliminate the source.

But what about my rats?, I asked him. How were they getting food? Clearly they were coming up an old toilet pipe from the sewer, and there wasn’t any food in my basement ceiling.

That’s where it got a little ugly. I was right about the combined sewer system, Corrigan said; it does make it easier for rats to get into toilets. As if to make the point, the day after we capped our toilet pipe, a rat popped up in my next-door neighbor’s toilet.

Plus, toilet drainage turns out to be a boon for sewer rats. “Lots of food gets flushed,” Corrigan pointed out. (This remains hard for me to fathom, but I do recall a landlord once complaining about a tenant who always flushed chicken bones down the toilet.)

“Also, if push comes to shove, human feces and dog feces contain undigested food,” Corrigan said.

“They don’t turn up their nose at anything that floats by.”

Let’s pause on that for a moment. What Corrigan is saying is that the rats in my basement ceiling were climbing up and down a toilet pipe into the sewer every day, whereupon they ate and quite possibly dragged back up caches of food that may or may not have included human excrement.

“That’s repulsive to humans, but it’s called coprophagy, and it’s part of the reason rats are so successful,” he said. “They don’t turn up their nose at anything that floats by.” 

Not Again

So it was smart of us to cap the sewer pipe. But little did I know when we cut off the entrance and exit to the basement ceiling, that at least two more rats remained in the ceiling—or that only one would survive. Survivor Rat chewed its way out of the house, leaving in its wake a gnawed-off condensation tube spewing water into the basement ceiling. Loser Rat didn’t hold out long enough and died in unknown quarters, spawning a new flock of flesh flies.

When the big striped monsters began to emerge and cruise the basement skies, I pretty much lost it. I Can’t. Do. This. Again.

Caving to the chemical solution, I bought a bug-fogging bomb and waited until I thought most of the flies would be emerging from their pupal cases—when I’d have the best chance of killing them. (Check out this video of  house flies emerging.)

I approached a hole we’d cut in the ceiling where I’d observed flies emerging. Using salad tongs, I pinched the plastic cover and pulled it back an inch. A rain of black flies drip-dropped from the hole onto the floor, buzzing. They had emerged from their cases but couldn’t quite fly yet. Perfect. I yanked the cover the rest of the way off, jumped back as a mass of flies hit the ground, some taking wing, and hit the button on the fogger.

Then I dropped my tongs and ran.

Those are dead flies. Multiply by entire basement.  Photo by Erika Engelhaupt
Those are dead flies. Multiply by entire basement. Photo by Erika Engelhaupt

Here is what I came home to.

It wasn’t as bad as Flymageddon.

40 thoughts on “Yes, Rats Can Swim Up Your Toilet. And It Gets Worse Than That.

  1. So rats (and mice, no doubt) are also part of the human ecosphere — a cloud of them follow us around. Maybe they served to feed the cloud of cats (house, barn, feral, and wild) which also follow humans around and regulate the numbers and locale of the rodents. I keep cats, which seems to obviate the rodent problem in my dwelling, but not everyone can do that, and the outdoor cats which would greatly reduce outdoor rodent numbers have been chased away by ignorant landlords and developers. So we have swarms of rats and mice outdoors, feasting on the torrent of garbage we provide. I wonder what else is out there….

  2. used to do commercial pest control as a younger man, nothing like sticking your head up into a drop-tile ceiling and coming face to face with one of these buggers – their eyes glow red in the blackness…

    is that so hard to do??? stop it with your plyboard homes, with houses made crossed pieces of wood that create tens maybe hundreds of spaces…
    Build a ** brick house, with almost all the spaces filled or not connected to each other, cover all the potential access points like pipes/around the cables/around the drainage pipe… but you americans build homes just like the piglet that build his house out of sticks…
    A house made of brick can have mice in it only if they come in thru the front door or if someone intentionally brings them inside!

    they cannot chew brick or concrete, they do not have tens upon tens of spaces in between the plyboard walls (or drywall for that matter), if you do not have a drop-tile ceilling they are unable to make nests over there, if you cover up any spaces between the water pipes/drainage pipes then the mice would have no way of getting in…
    your home is basically swiss cheese, and you wonder why there is mice in the holes… no holes no mice… EVER!

    but to me this trend of creating a “skeleton” of the house out of wood or whatever then covering it up with drywall or plyboard (or whatever you people use) is just stupid that is not a house that is a shed/shack/barn… it only encourages the idea that somehow houses are perishable and that you should just move the ** out… poorly built homes look nice on the outside, it’s only after you take down the drywall and plywood that you actually realise that you’ve paid a lot for some criss-crossed pieces of wood with drywall on top of them

    1. Actually, brick construction is no guarantee against rodent entry. My house is a brick rowhouse built in 1924, very typical for Washington, DC. And rats find ways into these houses all the time. They can come up through sewer pipes (even more easily if your area has a combined sewer system), chew through seals around the many pipes and wires that enter homes (we have to examine the entire exterior every year), find ways in through the roof, or burrow into the ground and find underground entries (yes, exterminators see it all the time here). Rats and mice are often using houses for shelter, and bring in food from outside. The ultimate solution for controlling rat populations is to eliminate their food source, which is largely our trash. Rat-proofing garbage cans and rigorously enforcing littering and trash-control ordinances are solutions that are not glamorous, but they are effective.

      Swear words have been removed from the comment above.

      1. Now that is an excellent idea but what people don’t understand is that rats can chew through bricks and concrete. Disgusting as they are they are very resilient.

    2. except that they can chew through concrete and steel… if that one statement didnt invalidate your entire point you may have a good point, but it does so you have no point at all. just a rant

  4. I kind of admire a rats tenacity
    There must be better ways to control numbers though. There should be more study done. I think people fear rats irrationality, it’s better to understand them and from that learn to avoid problems with Rats.

  5. I understand your points on common “sewer rats”, however, you fail to realize that rats make one of the best domesticated pets. Rats are smarter than cats and dogs, they rarely if ever bite for no reason, the are great for children with allergies to animals and the list goes on for a while. Unfortunately the picture of rats is painted by what people hear and see in media. “dirty, disease filled flea bags who spread disease everywhere and ruin your house” is what people think. That is so far from the truth. Domesticated rats have been disease free for decades, you can train a rat to do tricks, rats will come when they are called. After my son had allergies to dogs and cats, and a hamster bit him, i got a rat. It was the best decision ever. Sadly, the lifespan is only on avg 2 yrs but it was a wonderful pet to have.

  6. I’m thinking that rats getting rid of human sewage is not the worst thing in the world..at least it’s not going into the oceans. There must be a purpose for a rat population in this world, as there is for any creature, really. Maybe finding a way to keep their populations relatively manageable, and their diseases away from us humans might be something to consider?

  7. Dearth of studies? Google Scholar lists tens of thousands of papers on rattus norvegicus, about 20% in the last five years.

    1. Lots of studies (medical, etc) use lab rats, as I noted, but not so many studies of rat behavior in the “wild.”

  8. I find it odd that the video producers made it significantly easier for the rat by having the trap and main drain completely filled with water.

    The level of the water is sitting well above the trap lip, and the tube going down to the sewer is filled with water. This isn’t the way a toilet at rest looks at all, except when it’s actively flushing. Normally the main drain is completely empty except for air.

    I’m guessing this made it easier for the staged rat (it could simply swim up, instead of trying to climb a vertical drain), but also randomly forced it to hold its breath — a point they explicitly raised when they mentioned a not-actually-existent pocket of air at the top of the trap.

    I’m completely confused why the producers did it like this. Do they not know how a toilet works? Was it supposed to specifically show a rat swimming up during an active flush? Or were they simply not able to coax a rat to climb to the top in the real situation, and that was ruining their video?

    Even during a flush, the main drain isn’t filled like that, it’s more like a waterfall. I doubt a rat would be able to swim up during a flush. The way this was presented seems bogus.

  9. “I was, of course, trying not to be indiscriminate at all. I wanted to kill them all—the whole rat family.” You thought killing Cecil the lion was bad, eh? This guy wants to indiscriminately wipe out an entire family!! “Ruin his business!!” “Burn him at the stake!!” “Torture him!!” “How dare he, filthy human being, imagine he can kill one of US animals?!!”

  10. An analogy that I thought of: wild pariah dogs and King Charles spaniels are the same species, but no-one would think that studies on the latter would tell you anything about how the former live.

    Lab rats and pet rats have been bred from feral stock, but studies on the bred individuals doesn’t tell how their feral cousins make their living.

  11. My question is why is there water in the pipes. The toilet bowl should be the only thing full of water. The rat should have a fairly dry crawl up until sharp turn in the toilet assuming no one is flushing it.

    1. The black rat or roof rat, Rattus rattus, is found on the lower half of the East Coast (and in the Southeast and West Coast), but it is not more common than the Norway rat. The Norway rat is found throughout the US and is the common “city rat” found in most urban areas. Here’s a website with more on R. rattus: http://icwdm.org/handbook/rodents/RoofRats.asp

  12. I’m fighting this battle right now and am at my wits’ end. I had the exterminator in to seal the outside of the house and trap. He only got 1 in 6 weeks, so he had me call the plumber. Plumber came in and spent 3 hours with cameras and then cutting into wall. Couldn’t find an open sewage pipe. Exterminator still thinks they are getting in thru an unknown pipe. We hear them on the ceiling of our bedroom every night. Next step is to cut into the ceiling. Open to any other ideas!.

  13. to fight a rat invasion in your house you simply need to take advantage of their social behavior. If one rat enters your home and finds food it will carry the good news back to its family. If you catch the rat and kill it another explorer will find its way in your home. If the rat however has some unpleasant events while in your house but survives, the bad news will be transmitted to the rest of the family. I learned this from an old men at the hardware store way back in my younger years when my parent’s apartment in the city had a rat invasion. Just like this article mentions it found its way in our apartment through an old unused sewer pipe. We caught the first and killed only to be followed by another one next day and so on for the a couple of weeks. After hearing that piece of wisdom at some point we caught a rat alive and manage to stick a piece of wire about an inch long just under the skin without killing it. We then released the rat back into the sewer and we never had rats since. My parents still live in the same place and decades later still no rats!

  14. Yeah, that would apply to houses on concrete pads and connected to sewer systems. That would give the almost horizontal outflow pipe. The toilet water is in the bowl and up to the “lip” before the outflow pipe. That is right. Mine is a 4″ out flow pipe and goes vertical downward. No rat can climb that unless he had suction cup feet.
    The fact the upstairs toilet was removed and nothing was placed over the opening means a “sewer smell” to the house…as that would just fume sewer gases.
    I heard ( and it may be an old wives tale) my dad said that a field mouse’s skull could collapse so it would fit through very small holes about a 25 cent piece. Or under doors that had big openings at the bottom. Most of the time they come in when you leave the door open(like in the summer time)
    Stick structures can be just as tight if not tighter than brick buildings and I ain’t seen anything get in. Razor sharp claws just do not clamp to ABS plastic or vertical cast iron. Every pipe is either grated(like a floor drain) or capped off when not in use.

  15. Mark C – I feel your pain. We are in a similar situation, living in a 85 year old house in Montreal which we bought in May of this year. We have had smoke tests, sewer camera tests performed and apparently nothing is wrong with the pipes which only leads to a more puzzling problem: finding their entry way. At this point, the exterminator wants nothing to do with me and ignores my calls – if its not a sewer entry way, they response is a flat: theres nothing more we can do (regardless of the 600$ spent on their so-far useless services). Instead of being in the ceilling, the rats are living freely in the space between my foundation concrete slab and the basement floor itself. We are not trying to stay positive and having seen the Martian (at the movies last week) we will now try to science the shit out of this problem… We have installed motion activated cameras under the floor- FAIL, rats are creatures of habit and either they never adjusted to the change or our camera placement was faulty. We are now going to lift the bath from the basement bathroom (all of the 9 rats we caught in traps in the past 3 monts have been found under the bath, accessible through small traps destined to provide acces to the bath’s whirpool engines). Now pressure to find the entry way is mounting as the rat nesting is bound to start as we head in sub zero temperatures in Montreal. If anyone has any wisdom to share, ideas or suggestions – all would be welcome at this stage.

    1. I found a way to keep them out of my attic by running a diffuser 24 hours a day w/ peppermint oil in it. I live in a condo and all our attics are connected and I couldn’t get everybody on board for an exterminator so my choice was to get rid of them in my attic. Now apparently they have sealed up all the problem areas but didn’t get rid of the ones already living in our attics so I’ll be interested to see how much damage they cause as they have to eat.

  16. I want to recommend a book that I found absolutely fascinating. I think everyone who read your article would enjoy it immensely. Good luck with your rats.

    Rats: Observations on the History and Habitat of the City’s Most Unwanted Inhabitants by Robert Sullivan

  17. I had a rat living in my house who learned to avoid conventional traps after some rough encounters. I invented a new kind of trap that might be useful to others. I took a gallon bottled-water container (the kind with a narrow neck and slippery sides) and filled it 1/4 full of water. I then made a little plastic thing which floated some cheese and peanut butter in the water. I made a platform for the rat to crawl up to the lip of the bottle, and added some traces of cheese and peanut butter there. Not enough to satisfy the rat, just enough to make it crazy to get to the mother lode in the water. I also added a bit of loose dry weak grass to make the inside of the bottle less strange to the rat. It fell for my plan on the very first night, and I had a bottled rat.

  18. We’ve had a rat problem for a few months and now have mice as well. We tryed catching it alive but they avoided the traps then killed and ate a pet bird which was so very sad. I declared war then and would love nothing more than to see that rat bastard die a slow and painful death but they have been avoided all the traditional traps too. I found its nest yesterday under the couch and vacuumed it up but that apparently made it try to find a new nest and I woke to it crawling on me under the covers in bed. Fucking disgusting. Not sure what to do now, I don’t want to lay bait after your last post. Our remaining bird has been sleeping at night in a cage next to our bed but she’s being terrorized there too and I’m scared to leave our baby to sleep on her own at night as well. I HATE rats. Think we might have to borrow the neighbours cat to sort it out.

    1. Get Tomcat black plastic snap traps, fill them with peanut butter, place them strategically along the walls and anyplace else you find evidence of rat droppings or markings. You will catch the rat.

    2. If you put the bird in a hardware cloth cage, 1/2 inch hardware cloth, no mice will get in. Or move him to this cage at night at least. Use heavy hardware cloth and they won’t chew through it.

  19. Erika, THANK YOU! I read flymeggedon and this one and well, you make my listening to a ‘mice gone wild’ in my room, after eating poison, a much lighter matter. They will leave! (My peppermint spray did not seem to work as well.) Thank you for the helpful tips and humor. I enjoyed your articles. You are a gifted writer. May God bless you, Jay and your home!

  20. About a year ago, I heard my mother scream in terror and then saw her running to the door, holding something wrapped in a towel and throwing the thing outside, on the concrete floor. She then proceeded to tell me the horrifying story of how she was brushing her teeth over the sink, when something pushed up the drain stopper and popped its little head up. Suddenly, there was a smallish rat in the sink. We’ve never had a rat in our house or near our house before. We’ve always lived with cats and perhaps that’s why rats never dared to come near us. Anyhow, the rat was now in our yard and we were all looking at it, cold and wet, shivering, unable to move, trying to crawl away, as two of our cats were moving slowly towards it. It looked as if it had been hurt and it couldn’t move its hind legs. I was cheering the cats on, begging them to kill it as quickly as possible, because it looked like it was in pain. Then, just seconds before Romy, the deaf cat jumped on it, the rat produced a gut-wrenching sound and I was suddenly 100% sure it wanted to live and was asking for help, so I picked it up and took it to my room. For the next hour, I kept it in my lap, warming it up with an electric fan heater. Its fur started to look all fluffy and nice and the little creature seemed to enjoy itself when I rubbed its head with my finger. I could swear it was looking at me with gratitude in its eyes. At not point did it try to bite me or run away. It just sort of got comfy and tried to hide it’s face in my uderarm area, just like my cat does. I then let it rest for 20 minutes in a shoe box and when it regained its strength, it was like a completely new creature. It was cleaning itself and was able to move normally. So I took it outside and let it go, but it didn’t leave right away. It just stared at me for a couple of minutes, sniffing the air and cleaning itself. Then it ran away. I hope it had many babies and I hope it taught them not to get lost in the drain of my sink.

    1. You aren’t the sharpest tool in the shed! Should have given the cats a treat! If I knew you personally and you told me that story, I would never visit your home ever again! It hasn’t been that long, he’s probably gone to tell the rest of the rats in the city about how gullible you are and they will figure out how to destroy your house next.

  21. in Turkey, we have cute stray cats everywhere, people put food and water for cats on streets, no rat problem 🙂

  22. Actually, rats are very tuff, and they are also very adaptable. We can compare them to cockroaches, but still roaches win. I have seen them on the fifth floor, and now in the toilet. Need to do something before these disease spreading rodents come inside your house.

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