Replaced my sink and shower S traps with waterless self-sealing traps. Now no more gray tank odors from loosing the water seal in the home style S trap (HOPEFULLY).
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Glad you brought this up. I have more than just foul odors - on steep inclines with a full grey water tank, I get grey water in my bath cabinet. I should have realized this when designing it - if I'm on a steep Seattle hill and the level of the grey water tank is ABOVE the level of the bath cabinet drain, of course it's going to drain back up into the bath cabinet - even with an 8" difference in height from the bottom of the bath cab to the top of the grey water tank. Do you think this valve is robust enough to handle liquids as well as gasses?
Now if we're going off road somewhere I have to remember to empty the grey water, or put a plug in the drain.