I have recently installed an upflush toilet, which, by the way works just fine, but I have a little issue with the grey water. I have a shower that is plumbed in next to the toilet, connecting to a 3" sewer pipe. The upflush also connects to this pipe a little further down, away from the shower. When you flush the toilet, the maceration unit pumps the grey water (at this momemt in time, it is still clean, fresh water!), but since the two are plumbed so close together, the upflush is pumping the water so strong, that it is coming up into the shower. Is there any kind of one-way valve that I can put into the shower to allow the water to drain away, but would prevent the uplush from discharging into the shower?