holding tank question

[ruthi]

We are having a bit of a problem getting a configuration for the floor plan and lining up the holding tanks in the basement. Just wondering how far the toilet can be from it without it causing a problem.

[4104GA]

 :)my pipe from the john is about 45 degree angle to the tank.  No problem in 10 years of use.

[ruthi]

The reason I am asking, we were told by someone, no names mentioned, but someone who has been in bussing many yrs. that you can run it as far as you need to. I would think you could run into problems by going too far. I think we will just have to rearrange our floor plans to accomodate.

[TomC]

I really don't know why everyone is so afraid of running your toilet drain a few feet to the tank.  After all your toilet at home runs all the way under your house, then all the way to the middle of the street by gravity only.  If you have a down slope pipe all the way to the tank, it will work every time.  The only time it might not, is if the bus is on a slant the keeps the sewer pipe from being in a down hill direction.  Good Luck, TomC

[gumpy]

I really don't know why everyone is so afraid of running your toilet drain a few feet to the tank.  After all your toilet at home runs all the way under your house, then all the way to the middle of the street by gravity only.  If you have a down slope pipe all the way to the tank, it will work every time.  The only time it might not, is if the bus is on a slant the keeps the sewer pipe from being in a down hill direction.  Good Luck, TomC

Just wondering if you have any personal experience with an RV toilet run under the conditions you describe?

The problem with running the lines out horizontally away from the toilet to the tank is that RV toilets typically use less than a quart of water. All household toilets manufactured since 1992 are required to use less than 1.6 gallons of water per flush. Now it doesn't take a rocket scientist to figure out that higher water volume will more easily push solids along a gravity sloped drainpipe. It also doesn't require an Einstein brain to know that houses don't generally change their orientation to gravity, while buses are seldom if ever level, which, unless you've designed one amazingly complicated plumbing system, will surely affect the abilities of drainage.

Without being too graphic here, consider that friction is not your friend when it comes to soft sticky substances going through a pipe at low velocities. You have to have a cushion of water around and under said substances to keep it from sticking. Once it sticks, and then has a chance to sit, it begins to dry, and sticks even more, and then will become a blockage as the next flush comes down the pipe.

So you have make a judgement call on how little slope is acceptable for the volume of water your particular toilet uses, and the distance you wish to run it. Most standard RV toilets are designed for a straight drop into the tank. Does that mean they won't work with a 45 degree bend? Probably not. How about a 60 degree offset? How about a 90 degree offset? How about a 5 foot offset to the opposite side of the bay? And along the judgement line, you have to factor in how well you like dealing with a clogged line because you deviated from the manufacturers recommendations, and miscalculated your particular installation. Of course the decision should also include the size of the tank relative to the horizontal offset distance. The shorter the tank, the more slope you can maintain. With a tall tank, you're more likely to restrict the slope due to limitations of space below the  floor. Obviously, you can't run the line into the bottom of the tank. 

Yes, your toilet can probably be offset from the tank, but there is no general rule.

[robertglines1]

I have run about 8ft maintaining 3/4 inch to a foot drop...no problem....just remember how far we run at RV park sometimes almost flat..would maintain at least 3/4 min drop.regular plastic sewer pipe only ;no RV sewer hose for connection toilet to tank!

[cody]

The advantage to the rv park hookup is a person normally has a pretty full tank pushing it but still after the tank itself is empty we still have to lift the hose and let it run out, our tank is offset from the toilet by about 4 ft with a 45 coming thru the floor then another 45 above the tank and a straight drop in, I tryed to keep a decent angle between the 45's and allow a little extra water with the flush to help push.

[jjrbus]

 I was in the situation where the practical space for the holding tank and the toilet did not line up. They were off about one foot. I put in 2 45 degree elbows to compensate for the offset, one attached at the floor flange one at the tank, with about an 18 inch drop. The drain line was in no place level. This worked without a problem full timing for years.
Taking into consideration the solids that have to be moved and the available amount of fluid to move them, also the unlikelihood of the bus being perfectly level 100% of the time. I would not be willing to trust a 1/8 or 1/4 inch slope over several feet.
You could run a test take a 3 inch pipe the length you think you need and see how much slope is required to consistently move solids through it with a quart of water
                                                                                                                                             JIm
                                                                                                                                   HTH

[bevans6]

The other option is a macerating toilet and put it where ever you want.  I think that's a great option to optimize both above and below the floor layouts.

Brian

[scanzel]

My holding tanks is low profile 16H x 24W X 72L and I will need one 45 at toilet flange and one 45 at tank with about 3 ft in between the 45's. I found a 3" fitting that has a 1 and a 1/2 " side tap so I will have my shower drain into the same 3" pipe that the toilet dumps into so this will flush out any possible build up. The shower P trap will be before the 3" toilet pipe. My 3x3 acrylic shower stall and toilet are next to each other because I am doing a side isle full bathroom.

[Len Silva]

Two to four feet is not going to be a problem.  So maybe occasionally, you need to use a little more water or flush twice.  Mine was about 4'-1/4 feet with maybe a 2" slope, never had a problem.

A consideration is how you use your bus, size of tanks and how conservative you have to be with water.  I think the typical busnut with large tanks and 3-5 days between dumps would not have a problem.

[ruthi]

Gumpy, your thoughts were what we were thinking. We use the bus pretty continually, and we do have to be conservative with water as we are in one spot, no hookups for 5 or so days at a time, and four people. Thanks to all for the opinions, and advice.

[gus]

My waste system is not like most others. It was that way, except for the tank vent, when I got it four years ago and I see no reason to change so far.

My toilet is not connected directly to the tank. It is on the opposite side of the bus from the tank (one tank only). The toilet pipe passes forward into the next bay, then across that bay back into the rearward bay and then into the bottom of the tank instead of the top!! It has very little slope anywhere and there are two 90* Ls in the line??

According to everything I've read on the forums this won't work, but it does, even on an opposite slanted parking spot??

This thing defies most all busnut postings. It was on the bus when I bought it and it works fine.

The only thing I can figure that makes it work is that we always use plenty of water to flush solids. Our toilet has two pedals which allows adding more water to the bowl without flushing, which we do for solid waste.

It seems to me that not having the toilet empty directly into the tank is much better than looking down through that big hole at all that mess every time the toilet is flushed. It works well so I see no reason to change.

It also seems to me that having the toilet drain into the bottom of the tank instead of the top blocks a lot of waste tank gas from rising up into the bus since most of the gas is in the top of the tank.

[JohnEd]

Gus,

No shiX    I just had to say that.

I have been reading on this topic for years now.  It has always occurred to me that running the toilet drain down and into the side of the black tank should work.  Never said anything cause I thought I would take a lot of shiX.  There are people like that around here, no shiX.   Also, thought that the pipe would then function as part of the tank to boost your shiX threshold a couple critical gallons.It for sure you don't want that shiX laying up there in the pipe without moving.  That shiX ain't Gorilla Glue, is water soluble, but still you don't want it still till the very end.

Gus would end up with a very shiXty problem if he were one of those guys that kept his tank drained dry all the time while in use or didn't flush it before putting it up wet.

One of the really nice features about doing it their way is:  When you flush you toilet, the load is dropped quickly and creates a positive tank pressure.  The gases get a puff up the vent.  Inertia keeps them going up for a brief instant.  That is why you can see straight down into the tank and not get a back draft.  We all know you have not gotten that backdraft cause you would be on the board crying and whining and blubbering.  That smell far surpasses shiX.  You can taste it in the air.  Never go there.

All that being said, and I am serious as shiX on this, I would do a "GUS", as it shall be ever more known, if I had to.  Fall back, if it gets shiXy, is a macerator.

John

[Bill B /bus]

MCI 102A3 Toilet is about 2 feet from drop into the waste tank. Two 90 degree fittings and a tee for 1.5 inch connection for kitchen and bath sink drains. The sinks' waste flow should move any stuck stuff into the tank. The tank vent is tee'd off the kitchen sink drain. Shower and washer drain is at the opposite end of the tank.  So far the system has worked for over two years.

Previous bus (GM4108), old school with two waste tanks, the toilet was above the forward bay and the black tank was in the after bay. About a 18" horizontal run, Worked for 12 years without any problems,

Bill