Since very recently, our washing machine's drain pipe started overflowing. It has worked fine for the last couple of years but for some reason it doesn't anymore. When the washer dumps only one load of water the pipe instantly overflows onto the floor. We checked for clogs and cleaned it out but found nothing.
NB: When I say "we" I mean me and the other tenants, as we share a washing machine and dryer.
I'm not able to take pictures at the moment, so I drew a rough idea of how it's all connected. I added some numbers to indicate points of interest, I've explained them below the image. It's not quite to scale but I did pay attention to the relative positioning of elements (like how the trap is at the lowest point). There's also a tough plastic clamp attached to the washer's hose to keep it in place at the top of the pipe.
- Unused pipe, what's this even for?
- This is a plastic cap with a white plastic ring in it, but parts of this ring seems to have broken off (judging by the rough edges).
- There seems to be a small leak here (droplets of water fall down).
The "neighbour" is my downstairs neighbour and he's the only one on the ground floor. Everyone's toilets and showers etc still drain fine, if it matters.
I'm not entirely sure what influences the ability to siphon properly, but I know air (both excess and absence of) is a big part of it. It seems like a simple fix so calling an expensive specialist is something we'd like to avoid.