Waste pipes

[Flight102C3]

What kind of slope in 4 ft is good? If not level front rear, side to side, your standard household slope won't work!! I know I can't always be level.   Thanks

[PCC]

My waste water pipes are sloped at 3/4" or more per foot, at least for the first 4 - 6 feet from the fixture. Then I make sure there is a vertical drop into the tank of at least 8" above the center of the holding tank. If the vehicle is parked at an angle that prevents flow at those specs, then walking around will also be less than comfortable.

My coach has all the plumbing drains within 7 feet of the vertical drop, into the macerating pump which pumps into the holding tank. None of my lines have yet returned anything I have sent away.

[gus]

My commode is on the opposite side of the bus from the tank (one tank only). The sewer pipe passes forward into the next bay, then across that bay back into the rearward bay and then into the bottom of the waste tank!! It has very little slope anywhere!! And there are two 90* Ls in the line??

I don't think a lot of slant will matter, but I don't know that for sure. It would seem to me the solids would move faster but that may be wrong. Sort of like a water slide, so to speak!!

This toilet sewer pipe is about 12' long and is also connected to the kitchen sink and shower near the commode!!

 According to everything I've read on the forums this won't work, but it does, even on an opposite slanted parking spot?? My setup violates all the rules laid out by the naysayers on the forum.
 
I probably wouldn't have done it that way but it was on the bus when I bought it but works fine.

The only thing I can figure that makes it work is that we always use plenty of water to flush. I don't mean great quantities, just a little extra. Anyway, I believe that the more water in a black tank the better.

Long may even be better because you aren't exposed to the whole black tank surface every time the toilet flapper opens. Since my sewer pipe goes into the bottom of my tank the only surface area my toilet sees is whatever is in the drain pipe.

I also have a tank vent which makes a loop above the tank then back down through the floor. I'm not recommending you do this because the code police will get on my case, but it works for me and a few others.

[eagle19952]

I also have a tank vent which makes a loop above the tank then runs back down through the floor.
I do tooo...oh noooo,

[gus]

Oh no, the code police will get you!!

[Scott & Heather]

Ditto....black tank vent loops above tank and drops down through bay floor 

[Kwajdiver]

My bathroom sets above the gray/black tank.  Waste runs through a trap straight into the tank. Simple..

Bill

[belfert]

My bathroom sets above the gray/black tank.  Waste runs through a trap straight into the tank. Simple..

Do you actually have a trap on your toilet?

[Dave5Cs]

1/4 inch per foot is standard. If to steep the water will flow over the solids and sooner or later you will need to clean it out. If not steep enough nothing will move. In a RV the vent should be up and out and the entrance to the tank should be on the top, generally straight down into the tank from the toilet. Separate tanks for Black waste and grey waste, but again some have 1.

But as you can see what works for some works good and if it ain't broke don't fix it.

Dave5Cs

[Kwajdiver]

Oophs,  now that I go back and look at photos, I don't have a trap.  "The mind is a terrible thing to lose".

If the picture works out, notice the large PVC pipe on the right. That comes from the toilet.

Bill

[arutkow]

Standard household toilets have the trap built in (you can see the shape of it in the porcelain on some toilets).  I assume the standard rv toilet doesn't need a trap to block gasses, since it has a physical valve that opens the bowl to the drain pipe.

Am I right?

[belfert]

Standard household toilets have the trap built in (you can see the shape of it in the porcelain on some toilets).  I assume the standard rv toilet doesn't need a trap to block gasses, since it has a physical valve that opens the bowl to the drain pipe.

Am I right?

Correct.  RV toilets are not intended for use with a trap.  The water sitting on top of the valve blocks gases from coming in.  The reason they don't use a trap is to conserve on water usage.