Before we get to the heart of the matter, we feel it is important to remind you that rats require only the smallest of holes to gain access to a building. It is believed that adult rats would need a hole around the same size as a wedding ring — ¾ of an inch — and whatever is not already that large, will be chewed until it is then large enough to squeeze through.
Rats and Plumbing
Rats CAN get into a house or building through the plumbing, but more modern homes will have a special valve inserted into the plumbing works to ensure this doesn’t happen. We all know (or should do) that rats live in the sewers, and our homes have pipes that lead right to the sewers, but the valve only allows one-way access essentially. The stuff that needs to get out can get out, but rats and other sewer-swelling critters will not be able to get in.
Rats, especially the brown rat (or Norway rat), are pretty good swimmers, can treat water for longer than most humans, and have absolutely no problems living in dark, damp, and otherwise considered revolting conditions. Plumbing works that have fallen into disrepair will allow these creatures to gain access, firstly into the sewer systems itself, and then further on from that — into homes and commercial buildings. Many governments have updated their sewer systems and waterways to ensure that rats are not too much of a problem, but this is an ever-evolving animal and for every method that we come up with to put them off, they somehow manage to find a way around it. Sewer systems that are not well-maintained or have suffered damage as a result of a disaster, such as a flood or earthquake, are likely to be home to rats.
Brown rats specifically are very good climbers, which means that the lower level pipes are probably not going to be as hard-hit as you might think. It is very common for rats to enter buildings and to then live in the pipes and ducts that are found in the upper levels, including the attic. Paying attention to the lower-level pipes and where they enter the building is important, but you cannot forget about the ones that are higher up on the building.
How to Prevent Rats in the Plumbing of a Building
The easiest way to prevent rats from getting into the pipes — and your building in general — is to make sure that inspections are kept up with and the building is properly maintained. There will be repair work from time to time; that’s part and parcel of property management. When you leave those little jobs for too long, they’ll become bigger and more costly jobs. A small hole that is overlooked or ignored now can soon become a much larger hole, that is home to a colony of rats that is hundreds or thousands of rats strong. By avoiding rat holes and potential vulnerable patches, you can rest in the knowledge that you have enough of a barrier between you and the animals on the outside world.
As well as making sure that your home is well taken care of, you should also pay particular attention to areas that break up solid walls, such as where pipes and ducts or vents enter/exit the building, windows and doors (and their frames), corners, where the chimney or ceiling meets the walls, etc. Those are usually home to many common rat entry points.