In this diagram, you can see how water in the plumbing trap prevents sewer gases from getting through (back into the home) by creating a liquid or water seal. Sewer gas can’t get past the seal of water at the bottom of the U-shaped trap. This trapped water creates a seal in your pipe, which prevents any sewer gas from coming up through the drain and into your home. Water is trapped at the bottom of the U-shaped P Trap. Put another way, here’s what’s happening. However, in order for these plumbing traps to work - by “trapping out the sewer gas emissions” - water needs to drain into them to create a liquid seal. The traps stop smelly sewer gases from coming up from the floor drain and into your home. More so, each plumbing fixture - from kitchen sinks to toilets to showers to water heaters and more - is required to have a plumbing trap. This keeps your floors dry and safe from water damage. The floor drains allow water to flow from your house and into a city’s sewer or storm drains. How Does a Plumbing Trap Work?Īll plumbing fixtures in a home have floor drains. And yes, there are other shapes that accomplish the same thing. It’s just a U- or sideways P-shaped pipe that keeps water flowing out while keeping sewer gas from floating in.

Take a look under your kitchen sink or bathroom sink to see one for yourself. It can be made out of metal or PVC (a synthetic plastic polymer which has a white-plastic look). This U-shaped pipe also looks like the letter P on its side. A plumbing trap looks like a U-shaped pipe.

To keep that gas out, your drain requires a trap, and that trap needs a trap primer. When that happens, it’s quite possibly due to sewer gas coming into your home from your floor drain. What Is A Trap Primer And Why Do We Need It?.

Trap primer troubleshooting