Found this setup, and am not sure how to write it up. The vertical pipe behind the clothes washer is connected directly to the washer, check valve, no trap. The vertical pipe on the right is connected to the laundry sink drain, which has a manually switched pump, check valve, and no trap. As you can see, both lines connect to the outgoing line, which goes to the septic system. The good news is that it works.
Very ingenious, IMO. Obviously a gravity drain was out of the question since the main drain line is above all the appliance and laundry sink,… waste water has to be forced up to it some how. The washing machine uses its own expulsion force to send the gray water up and out and the laundry sink, like you said was fitted with a pump to do the same. Pretty Cool! Owner must work for NASA! lol
Only other way is to install a sump pit in the floor,… which would do the same thing (pump waste water up to the main drain line) which is exactly what this set up does. I think its cool. Maybe non conventional but still cool.
Recommend a licensed plumber for further evaluation. Actually, the washer could discharge into the laundry sink if equipped with trap and pump with an automatic on/off switch.
actually my main problem was the stand pipe above the washer with only a check valve…washer lint can easily clog the check valve and then trouble…ingenious maybe, but wrong yes …