It sounds like an urban legend. Then a picture of a wet rat in a toilet bowl shows up in a neighborhood group, and suddenly you're looking at your own bathroom differently. So can it actually happen? Yes. It isn't common, but public health departments get these calls often enough to publish instructions for them.
Yes, rats can come up through a toilet, though it's uncommon. Norway rats (Rattus norvegicus), the species also called sewer rats, live in sewer lines, swim well, and can travel up a home's sewer pipe and through the water in the toilet trap. It happens most with old or cracked sewer lines and after flooding or heavy rain.
How Does a Rat Get Into a Toilet?
Every toilet drains into a pipe that runs from your foundation to the city sewer main. Plumbers call that pipe the lateral, or side sewer. Rats that live in the main sewer can travel up the lateral toward your house.
Public Health Seattle and King County explains why they head that way: rats follow the scent of food washed down your drains. Kitchen sink pipes are too small for a rat to get through, so the toilet is the opening big enough to use. To get into the bowl, the rat swims through the water sitting in the toilet's trap, the curved section that keeps sewer gas out.
The Allegheny County Health Department in Pennsylvania adds that rats can crawl up the house drain and come out through uncovered basement floor drains, roof drains, sewer vents and toilet bowls. The University of California Statewide IPM Program lists "entering through toilets or broken drains" among the ways rats get into buildings.
Which Rats Do This?
The Norway rat, also called the brown rat or sewer rat, is the one to blame. The University of California notes that Norway rats are more powerful swimmers than roof rats (Rattus rattus), and indoors they stick to basements and ground floors. Allegheny County points out that sewers stay warmer than the surface in winter and cooler in summer, and that garbage disposals send a steady supply of bite-size food down the line.
Roof rats are climbers that favor attics. They can still use the plumbing from the other end, which is why the University of California recommends screening rooftop vent pipes more than 2 inches across. If you're not sure which rat you have, see roof rats vs. Norway rats.
Why Would a Rat Come Up My Toilet?
An intact sewer line with no food in it gives rats little reason to travel your way. Trouble usually traces back to one of these:
- Old or broken sewer pipes. Allegheny County says rats find breaks in older brick and clay pipes caused by age, settling, tree roots and digging, and can burrow up through as much as eight feet of soil from a break.
- Flooding and heavy rain. King County notes that floods and storms can drive rats out of the main and into the side lines that run to houses. That matters in low-lying parts of Charleston, Mount Pleasant, Norfolk and Virginia Beach, where street flooding after a heavy storm is familiar.
- Food and grease in the drains. More food down the drain means more scent to follow.
What to Do If You Find a Rat in the Toilet
Public Health Seattle and King County publishes these steps, and they're good ones:
- Stay calm and close the lid so it can't climb out.
- Squirt liquid dish soap into the bowl. Soap breaks the surface tension of the water and degreases the rat's fur, so it has a harder time staying afloat.
- Flush. The rat usually goes back down the way it came. You may need to flush more than once.
- If it gets out, shut the bathroom door to keep it in one room, set a rat trap, and call a pest control company.
Don't grab it. A cornered rat can bite. For what to do once a rat is loose in the house, see what to do if you see a rat in your home.
Is It Dangerous? Cleanup After a Toilet Rat
A rat out of the sewer has been in sewage, and the CDC says leptospirosis spreads through the urine of infected animals, including rats, and through water or soil contaminated with it. The University of California lists leptospirosis, typhus and food-borne illness among the most common diseases rats transmit.
The CDC's rodent cleanup guidance applies here: wear rubber or plastic gloves, spray the area with a disinfectant or a fresh bleach solution (1.5 cups of household bleach per gallon of water), let it soak 5 minutes, and wipe up with paper towels. Don't sweep or vacuum droppings. If someone was bitten or scratched, wash the wound and see a doctor. For more on the health side, read are brown rats dangerous?
How to Keep Rats From Coming Up Your Pipes
Most of the fix lives in the plumbing. In Allegheny County, the health department notes, repairing the house line is the homeowner's job. Check with your local utility about who owns which part of yours, then work through this list:
- Keep food and grease out of the drains. King County suggests scraping dishes into the trash, never pouring grease or oil down the sink, and using the garbage disposal as little as you can.
- Get the sewer line camera-inspected. Allegheny County says a plumber can check the house drain and lateral with a sewer camera, and broken or root-damaged lines may need replacing. Seattle Public Utilities recommends a side sewer inspection every 8 to 10 years.
- Watch for a burrow that keeps coming back. King County calls a rat hole in the yard or along the foundation that reappears after you fill it a sign rats may be using a broken sewer line.
- Cover floor drains and screen roof vents. Keep basement floor drains covered, and screen plumbing vents over 2 inches across, per the University of California.
- Seal the rest of the house. The University of California says to seal holes larger than 1/4 inch around pipes, wires and vents. See rodent proofing your home.
When to Call a Professional
- A rat got out of the toilet and is loose in the house
- You've seen a rat in the toilet more than once, or droppings near a floor drain
- A burrow keeps reappearing along the foundation or over the sewer line
A plumber handles the pipe. We handle the rats. Our rodent control service covers homes across Charleston, Columbia, Greenville/Spartanburg, Raleigh and Hampton Roads, starting with an inspection to find how rats are getting in. If you want someone to take a look, request a free quote.
Key Takeaways
- It really happens, but it's uncommon. Health departments in Seattle and Pittsburgh publish guidance for it.
- The culprit is the Norway rat, the sewer rat, a strong swimmer that can travel up a sewer line and through the toilet trap.
- Broken pipes, flooding and food in the drains are what bring rats up the line toward a house.
- Lid down, dish soap, flush. If it escapes, shut the door, set a trap and call for help.
- Fix the pipe too. A sewer camera inspection finds the break a rat is using.
Sources: Public Health Seattle and King County, "Keep rats out of your toilet and sewer"; Allegheny County Health Department, "How Rats Enter Homes From Sewers"; N. M. Quinn, "Pest Notes: Rats" (Publication 74106), University of California Statewide IPM Program; Centers for Disease Control and Prevention, "About Leptospirosis" and "How to Clean Up After Rodents".
Frequently Asked Questions
Yes, though it's uncommon. Norway rats live in sewer lines, swim well, and can travel up a home's sewer pipe and through the water in the toilet trap into the bowl.
Public Health Seattle and King County says rats follow the smell of food washed down drains, but kitchen sink pipes are too small for them. The toilet drain is the opening large enough for a rat to use.
Close the lid, squirt liquid dish soap into the bowl, and flush, more than once if needed. If the rat gets out, shut the bathroom door, set a rat trap and call a pest control company.
Yes. The Allegheny County Health Department says rats can crawl up a house drain and come out through uncovered basement floor drains, roof drains and sewer vents as well as toilets. Keep floor drains covered.
Keep food and grease out of your drains, use the garbage disposal sparingly, and have a plumber camera-inspect your sewer line for breaks.
It can be. The CDC says leptospirosis spreads through the urine of infected animals, including rats, and through contaminated water. Disinfect anything the rat touched while wearing gloves, and see a doctor if you were bitten or scratched.
Photo credits: Biswarup Ganguly, CC BY 3.0, via Wikimedia Commons; Photo: Giorgio Trovato on Unsplash.