Tag Archives: turned p-trap


S -Traps, P-Traps, J-Traps – Oh MY!

“Little Lady, the problem is you have an outdated S-trap. That’s illegal is some states, ya know, so I’m going to have to rip that out and install a P-Trap. It’s probably going to cost you.”

Don’t be fooled by the fancy alphabetical references, sink traps are everywhere, keeping sewer gasses from coming up through your drain. It’s true that some traps work better than others because of their shape, but most are a simple fix for a licensed plumber.

In our final blog about sink traps (because who knew there was so much to say about them) Brandon and Greg Sheck from G&C Plumbing and Heating want you to be in the know when interviewing a plumber for a job, however small. So, here is the rest of everything you need to know about sink traps…

The S-Trap

Invented by Alexander Cummings in 1775, the S-Trap was crucial in the success of indoor domestic plumbing. This simple S-shaped piece of plumbing solved the problem of sewer gasses traveling back up drains and into homes by providing an internal trap. Problem was, the S-shape tended to get clogged, required an overflow, and could easily siphon dry even when well-vented. So, introducing the…

U-Trap, Turned P-Trap, Turned J-Trap

Originally coined the U-Trap by Thomas Crapper in 1880, (No, we are not making that name up) Mr. Crapper (Yes, we will use that as often as we can) found the U-shape of the drain trap to be more efficient in maintaining a water seal to prevent the escape of sewage gasses into a building. Crapper’s new U-bend also didn’t clog, so, unlike the S-bend, it did not need an overflow. The most common of these traps is referred to as a P-trap or a J-Trap because of the later addition of a 90-degree fitting on the outlet side of the U-bend that created a P or J shape – depending on which way you’re looking at it. These are the shapes of a trap most often installed under a sink. Thanks Mr. Crapper!

Sheck Tip For Turning an S-Trap into a P-Trap

“In older homes with original plumbing (AKA New England Homes) it’s not unlikely to run into an S-Trap. We can easily convert it into a P-trap by adding a four or five-inch horizontal length of pipe on the outflow side pipe and connecting a vent. Venting is the trickiest part of this conversion, but we’ve got your back.” – Grand Master Plumber Greg Sheck who means “tricky” for the average Joe, which he is not.

As Shakespeare’s Plumber liked to say…

A drain trap by any other name, is still a drain trap.

S-Trap, U-Trap, J-Trap, or P, it’s keeping the sewage gasses out of your home or business, but don’t let someone fool you into thinking one letter is any more difficult to fix or install than the other!