Should washing machine trap be higher than sink?

[Bob49]

Hello,

I have a sink waste that after the trap has piping down to floor level where it then exits the house. At this point the plumbing for the washing machine trap joins the same waste pipe. It's one of those traps where you shove the washer waste tube down into the pipe. The top of the washing machine trap is less than the height of the sink.

Does this mean it is possible when emptying a full sink that it could overflow the top of the washing machine trap?

It doesn't seem to, maybe because the water drains away fast enough. But is this right? I thought water in pipes will equalize in height.

Thanks,

Bob

 

[just pumps]

Providing the washing m/c is on the floor then rule of thumb is around 36" in 40mm pipe.

 

[Madrab]

You won't have an issue with that under normal drainage. The water will always take the easiest downstream path. The only time it may become an issue is if the waste pipe to the outside blocked up and you emptied a sink full, the water would then find the lowest point to drain out of, that would then be the appliance stand pipe.

 

[Bob49]

You won't have an issue with that under normal drainage. The water will always take the easiest downstream path. The only time it may become an issue is if the waste pipe to the outside blocked up and you emptied a sink full, the water would then find the lowest point to drain out of, that would then be the appliance stand pipe.

Thanks, that makes sense.