Is there suppose to be a "p-trap" for the drain of our washing machine?

Question

For some reason there isnt a "p-trap" on the drain for our washing machine.Is there suppose to be one? It does run into our sewage pipe.

I am not a plumber but i do know what a p-trap looks like and how they work.Our sewer pipe does NOT have one on it.The sewer pipe runs straight in to the basement floor.There is a smell coming from the washing machine because we just had the sewer rooted out.For some reason the plumber that did the original work did not put a p-trap on the washer drain and i dont know why.I just wanted to know if there was a specific reason why he/she didnt install one,that way i should know to install one myself or not.Thanks.

There are a lot of good answers here!! Apparently i do need the P-trap.I will get one from the hardware store tomorrow and put it in.Since so many of you have mentioned it i will let this go up for a vote!!
--special thanks to Nickolas S for the cool idea on the rubber hose.I never thought of that.

Answer 1

based on everything i see, calypso was correct, if the plumbing was done right. based on your added details i'd say the plumber blew it.

you need to make up a trap in the sewer line. go down to the big box and pick up an s-trap in the right pipe material [pvc=white, abs=black].

you can also make one up with a series of 3 street 90 elbows plus one regular elbow. just cut the line added two el's so they loop back down and two el's so they loop back up. add a good length of pipe above to put the drain hose into.

good luck.

Answer 2

Seems you have a grasp on this, but let me confirm:

1. There is supposed to be a trap, "P" "S" or some kind.

2. If you smell sewer gas, that drain does not have one. That's fairly common on older lines cut in for laundry areas.

3. Go ahead and put one in. Set it as low to the floor as you can, and support it.

Good luck.

Answer 3

The reason for having a trap is to stop smells invading the house. If you have no p trap but have no smell there is probably a trap doing the job somewhere between the machine and the main drain. No problem.
But if there is a bad smell in your laundry room then you certainly need to fit a trap.

Answer 4

There should be some type of trap in place to prevent the fumes from the sewer coming into your laundry room. The water in the trap stops the fumes. There are several types of traps used. The "P" and "S" traps are the most popular. Either one will work for you. If the drain line goes into the wall, use the "P" trap, if it goes into the floor, use the "S" trap. Less popular are drum type traps.

Answer 5

The idea of the "p-trap" is to keep the fumes from the sewer from traveling out the opening where the washing machine hose is.. Does it smell of sewer at that opening? If not then there is a p-trap farther down the line keeping the smell at bay.

Answer 6

seems no-one answered your question.

there is a trap, it is not in the machine or on the line, it is on the sewer pipe in the wall or floor. if you pour a little water into the drain you should hear it splash into the water in the trap.

you don't need a second trap.

Answer 7

To answer your question. Yes, it should have a trap in the discharge piping. Normally, they are installed wherever the discharge pipe changes from vertical to horizontal. The trap needs to be the same size as the discharge pipe. Either 1-1/2" or 2".

Answer 8

If the discharge pipe from your machine is connected to a permanent pipe in the wall behind your machine, that permanent pipe ought to have a P-trap built in inside the wall. If your house is an old one, it may or may not have a permanent built in trap in the wall.

To make one without calling a plumber, attach a rubber pipe between your machine's discharge and the wall pipe and let the rubber pipe loop downwards about eight to ten inches to make the trap you may need.

Answer 9

Yes, there should be, that's what keeps the sewer gas from coming up into the room.

Answer 10

the p trap prevents sewer smell from coming back up the drain,, i would have one,,