toilet plumbing input

[bluebird90]

just want some input on the toilet plumbing.
First a description of my bus. Cool story how I got it, will be posting it and pics soon. 90 bluebird conventional, 38 ft. very good condition with the exception of the DT466 engine thats blowing oil from #2 cylinder.( doing an inframe in a couple of months)

Bathroom on the pass side just ahead of the rear axle main waste tank on drivers side ahead of the axle. I was going to fabricate a small black tank under the bathroom with a run under the drive line to the drivers side to a dump valve. On this bus I can actually do that and have a slight slope to the tank and still have some road clearance.
My thought is to not have a black tank and have the toilet line run across the bus to the main tank. (Single tank maybe 75 gal.) To ensure solids get to the tank, you would have to fill the toilet bowl with water then flush.

BTW, we will be spending most of our camping at sites with dump facilities.
Any thoughts?

[thrash]

I wouldn't.

One reason I put my bathroom and all my tanks behind the rear axle was to stay away from that driveshaft, and to keep the tanks and the plumbing tucked up high. Note that the drift shaft moves around as the rear axle moves; it would suck really badly to have that driveshaft somehow knock out your black plumbing. Also, unless you put a internal valve between your black tank and the cross-pipe, that cross pipe will always be filled with the nasty stuff. So anything that happens is going to cause a leak with the gross stuff in it.

Here is how I have my bus drain plumbed currently:


This photo is taken from behind the axle, from the driver's side.

The bus under body is divided into 3 "Sections" by the two frame rails. There is a center section, between the rails, and then there are drivers-side and passenger-side outboard sections.

The 25gal black tank mounted directly under the toilet, in the drivers-side outboard section of the underbody. Goes immediately into 3" PVC elbows into Valtera 3" + 1.5" double black+grey blade valve. Note that the valve bodies are mounted upwards at a 45 degree angle. I read a tip that mounting them straight horizontally means that crud collects in the bottom track that the blade rides in, which can lead to leaks or other problems.

Note that because of the double-valve assembly, my dump fitting actually rotates freely up and down. So when I am under-way, I tuck it up inside the bus. This photo is a bit deceptive; very little of the plumbing is visible from outside the bus.

The gray tank is mounted in the center section, and has a 3" -> 1.5" reducer. 1.5" PVC slopes down and crosses under the frame rail to tie into the valtera dump assembly.

Ideally, my grey drain should also be 3" dia throughout, but in the interest of time and using the pre-made valtera doulbe-gate assembly, I have it plumbed using 1.5 for now.

The reason to use 3" dump plumbing everywhere is so that when you dump your gray AFTER dumping your black, you can completely fill the pipes and the drain hose that just had your 3" of black stuff going through it. This helps clean out your dump hose and pluming much better.

I'd definitely run separate black and gray tanks. I found that my gray tank filled quickly, and once I over-filled it. I was happy that dishwater & hand-washing water was the only thing leaking out of the vent pipe in that tank. A lot nicer than blackwater leaking out of anywhere.

My basic idea is this: I do not ever want to do any maintenance or road-side repair of anything related to human poop, nor do I want to have "performance problems" or "quirks" in a system designed to keep my family's poop away from my family. So I adopted a "take no chances" approach to engineering the toilet and black system.

PS: I highly recommend the Wastemaster kit from DrainMaster. It is the cam-loc dump fitting you can see in the photo, and a special dump hose that is truly awesome to use.

http://drainmaster.com/site/products/mini-view3

[lornaschinske]

I strongly suggest that you either keep your black plumbing (ALL of it) on the drivers side Or you invest in a macerator and put ALL of your black plumbing on the passenger side. You need a straight drop from the RV toilet to the black tank. Some folks & manufacturers will put a 45° angled stub into the tank but even that is risky. If you go the macerator route, you can put the toilet/tank on the passenger side and place the macerator at the tank... then thread your waste line (it will be small) over the beams to the drivers side and put a connection (and macerator control) there. Keep in mind that if your macerator poops out then you will not be able to get your poop out.

[browncrown]

A lot of what you do gets dictated by the bus and where things are located underneath. I have a mid-ship engine under the floor as well as the transmission. As a result, I only have room for one tank and that is the route I took. Not optimal, but it works. It's also on the right side of the bus because that was the place it would fit (the tank) for a straight drop from the toilet to the tank. There is an 3 inch pipe running from the tank under the driveline, wall to wall to the port side where the valves are for the tank. The cross pipe has higher ground clearance than the engine and oil pan. 99% of my camping is done in a place with hook-ups. So far no problems, but keeping the fingers crossed. As others have said, 99% of campgrounds will have the hook-ups on the driver side.

[bluebird90]

The macerator actually sounds like a good idea. I really don't need to worry about drive shaft movement because the black pipe will run almost right under the rear carrier bearing. I can run the pipe right between the frame and exhaust with black iron pipe as the cross section. even have a cleanout under the toilet "just in case". also a valve at the tank for insurance.