Originally Posted by blrpix
Mine is a 20ft 65' Globe Trotter...I know the tank idea will work...BUT my shower is in the back, near the toilet...drains the same, bypasses the black water but comes out the same outlet. My concern is the run from the low shower drain to the new GW tank...does it need slope? I need to take measurements, but I could conceive that it could run flat, but with much slope it will lose tank capacity..correct? Thoughts?
slope would be optimal...so would having the drain line enter the tank from above...but in this kind of confined space, it isn't really practical. fact of the matter is that water will seek its own level. the shower drain is on the floor of the trailer; the highest point of an under-floor grey tank is going to be lower than that, if only 3/4 of an inch. therefore, the water will drain from the shower pan to the tank...no matter how high or low on the side of the tank the drain is attached. (as long as there the tank is vented from the top..that's "key"). it'll just drain slowly when the water level in the tank rises to the level of the drain pipe. you wouldn't want to do this in your house, where you might run the shower constantly for prolonged periods...but since RV showers are always "GI" type, due to the low hot-water capacity of the camper, the slow drain is not a big problem. really, no different than using a 3/4 hose from the sewer cap to an external "blue-boy". (I had a little standing water in the bottom of the shower this past weekend when I took a shower under these conditions....it drained, eventually.).
Last year, I experimented with mounting my huge blue-boy to the underside of the trailer, in the spare tire carrier. the belly pan is cut away in that area, opening the cavity formed by the frame just aft of the a-frame, to make room for a tire to fit up in there. I dont' have a spare, and I really wanted to go dry camping with a group, at a place where grey dumping was verbotten. so I rigged this up w/ a long piece of pex tubing, connected to the 3/4 fitting on the sewer outlet, and mounted the blue-boy on the spare tire carrier. ran the pex up over the axles, and to the front of the trailer. had garden-hose fittings on either end of the pex pipe. I attached the pipe to the blue-boy via a short piece of garden hose to another sewer cap fitting on the blue boy. (this blue boy is a 4-wheeler, so it has a dump valve, just like a camper's, mounted in the lowest spot; it would be too heavy to lift and dump otherwise.). so this drain dropped down from the trailer's sewer outlet, curved back uphill to where it was secured w/ hose clamps to the pan, snaked its way all the way to the front of the camper, then sloped down and under the blue-boy, and back up the other side, and then filled the blue-boy from the BOTTOM. and it worked. We took showers that weekend, and everything worked just fine.
I did find that it was a PITA to mount the blue-boy on the spare bracket, because its big, bulky, heavy, and just barely fits. but it did work in a pinch. It also hung down pretty low, too, which sort of made me a little nervous...but people w/ newer trailers have plumbing that has just as little ground clearance, so...
I posted a diagram here somewhere...I'll see if I can find it.