Plumbing

Attaching trap to vertical waste pipe for washing machine + dishwasher

Anonymous user 09/03/2024 - 3.28 PM

Hi all, Hope you're well! Would appreciate some advice please: I have a dishwasher and a washer/dryer in my kitchen (based in London). The waste/drain pipes for these machines were recently installed by some questionable builders (!) and there is currently a fairly strong smell coming from the pipes. I believe this is because they connect directly into the sewer nearby and there are no P traps (or similar) installed on the pipes to prevent smell from coming into the property. I am going to ask a plumber to fix this but want to be sure it's done in the best possible way under the circumstances. Here is a photo of one of the connections: https://photos.smugmug.com/photos/i-PpFD74N/0/ecfa3537/X3/i-PpFD74N-X3.jpg As you can see, the pipe is vertical and has been inset into the wall to allow a bit more space for the machine (the same will presumably need to be applied to any traps attached to the pipe). As the waste pipes are vertical I'm not 100% sure of the best way to attach a trap to them. Should I simply use an S trap? Or do I use a normal P trap but connect it to the vertical pipe with a sanitary tee? Is there a need for any kind of vent? Also, what should the placement of the P/S trap be? I've read that the waste pipe should be higher than the drum of the washing machine to prevent siphoning, so should the P or S trap be installed closer to the floor to allow for a taller pipe? Thanks very much for the help and guidance!