I have an SV34. The fresh water tank drain is under the bed. You have to take the bed support off to get to it.
The PVC drain pipe sticks out enough through the floor that I connected another 1” PVC pipe to it and a manual ball valve under the coach. I keep the valve under the bed open and then use the valve I added to drain it without taking the bed apart.
I just bought a motorized ball valve that I am going to install over the winter so I can just flip a switch to dump the fresh water tank.
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