If you’ve ever looked under your sink, you’ll see that it doesn’t just drain into a straight pipe. There is a u-shaped portion of pipe that is connected to a straight pipe. Leading to the rest of your drainage system in fact, it looks like a “p” lying on its side.

That portion of pipe is known as a p-trap and even though it sometimes interferes with storage space under the sink, it serves a vital purpose for your health.

The purpose of p-traps
The best way to understand the role of p-traps is to consider what would happen without them. After all, they seem like more of a hindrance than anything. Making waste flow through an extra loop before leaving the sink. But a pipe that runs straight to the sewer without traps will allow a free flow of smelly sewer gases back into your home.

P-traps are designed to hold some of the water flowing through them as a barrier between your open drain and the sewer system. Not only does it prevent the rotten smell from entering your house. It keeps dangerous gases like methane from accumulating and making you sick.

P-trap problems
P-traps that are not properly vented can lose their seal through pressure differences that pull the water out, leaving it dry. A dry p-trap is as useful as no p-trap. Hence there is a maximum distance allowed between the trap and the vent stack serving it.

Some drains, like floor drains, are seldom used. The water that seals the trap isn’t replenished and dries out, leaving an open path for sewer gases. To prevent this from happening, you can throw water down the drain at regular intervals, or you can have a professional install a trap seal primer. Trap seal primers provide a controlled flow of water to p-traps via a small tube connected to a supply pipe.

P-traps don’t just hold water. They are also prone to accumulate dirt, hair and other debris going down the drain. Some have clean-outs that can be removed to clear the unwanted gunk while others must be removed completely. To prevent backups, have your p-traps cleared as part of regular maintenance.

If you need assistance with your drainage system and its p-traps, give us a call and we can help keep the smells away.