Trained Eye


Rat in Bathroom


I have a perplexing problem that needs solving and I am hoping you can shed some light.  At first glance, the problem may appear funny.  I am a 73-year-old woman. My husband and I live in a bungalow.   Last Sunday, at about 2:30 A.M., I went into the bathroom on the main floor, and I was startled to see what looked like huge black beans, on the floor and on the toilet seat.  When I looked further, I saw it. I was repulsed with fear, horror and more fear. The “It” was a white furry animal, with pink eyes that had crawled on to the back part of the toilet seat cover. That explains the material that looked like black beans.  It was actually droppings.  Naturally I screamed. My husband, who has a heart condition, jumped out of bed and fell, injuring his hip that was replaced.   He is okay now but he was hurt.  An exterminator was called and he killed what turned out to be a white rat, which was removed from our house. 

 We have not as yet been able to locate the rat's point of entry.  There are no droppings elsewhere.  This suggests that the rat may indeed have come up through the toilet.  The City of Winnipeg confirmed that it was possible for a rat to enter our drains and come out through the toilet.  Apparently, this is not an urban myth.

 My question to you is this:  Have you ever heard of this happening before?  How is it possible for a rat to enter our drains and end up in the toilet? What are the mechanics?

 A plumbing contractor suggested that we put a backwater valve on the main drain.  I don't understand what this entails.  Currently, we have a backwater valve that was put in when we had our sump pump installed in 1997.  Would a backwater valve on the main drain do the trick?  Do you have any suggestions? I hope you don't think this is a foolish joke on my part.  I have been traumatized by the experience and I am wrecking everyone's life with the stress, ever since I saw the rat. I can hardly think of anything else.

I am desperate.  Can you help?


I certainly don’t think that you are joking with your inquiry, but it is one of the strangest situations I have ever heard of. Halloween is not until the end of the month, but this horror story grabbed my immediate attention. I think your worries should be minor, as this is likely a very rare, bizarre, onetime occurrence. The chances of it happening again are probably the same as getting hit by lightening, twice. Nonetheless, I will try to explain what may have happened and what your back-up valve could do to prevent another unwanted guest entering your bathroom.

The municipal waste sewer system is an interconnected series of underground pipes connected between the sewage treatment plant, at the discharge end, and homes and businesses, at the intake end. The pipes increase in size as the sewage goes further down the line and may be two to three times the diameter at the mains, under the street, than in your home. Insects, fish, rats, mice, and even reptiles have been known to survive in the larger sewer pipes due to the relatively constant temperature, year round, and the presence of various types of waste as a food source. They rarely make their way out, once inside, due to the slippery nature of the round drains. It is very difficult for any animal, other than insects, to grip the inside surface of a smooth pipe, covered with waste products, soap and grease. This is compounded by the fact that water is constantly flowing in the downward direction, preventing a critter from travelling uphill, or upstream as the case may be, in this situation.

Obviously, from your experience, this may be rare situation but can occur. You may even have a neighbour upstream that decided they were tired of their pet, and flushed it down the loo. The rodent may have been able to find a foothold in an area of the main sewer near the intake from your home. If your home is older, there are likely many tree roots or cracks in the older pipes that the rat could climb up on and enter the main sewer beneath your basement floor slab. It would have to travel almost vertical for more than 2 metres, through the main stack, to access your toilet and get through the water in the trap integral in the commode. This is not easy.

I am assuming that your back-up valve is simply the small, rubber ball type that installs in your floor drain in the basement catch basin. This may be the reason the large rodent didn’t come in your basement through the easier floor drain access. An inline back-up valve installed in your main sewer may help prevent another intruder, but it would be costly to install and may not be permanent protection for an industrious rat with sharp teeth. A better solution would be to replace your main stack with a new, smooth ABS drain that would be virtually impossible for a rat to climb, but even that might be overkill.

The best solution is to have regular cleaning of your main sewer by a plumber or Rooter contractor. This will remove excess debris and roots that allowed Willard the ability to climb uphill against the normal flow. If you have this service done on an annual or bi-annual basis it should not only prevent further nightmares, but allow for better drainage overall. Sleep tight!




P.O. Box 69021
#110-2025 Corydon Ave
Winnipeg, MB
R3P 2G9