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Old 04-06-2005, 10:57 AM   #1
Join Date: Jan 2005
Location: bossier city La
Posts: 21
help on black water and grey water hookups

hey guys and gals;
ive been on this project now for a couple months and i just order my tanks my question is. i know the toilets hook up with a standard closet flange dose the pipe go straight into the tank and if so dose the black water tank need to be vented thur the roof. same with the grey water tank. i will have a shower sink and toilet. any help would be great thanks all.while your here take alook at the bus and give me feed back good or bad i can take it the more feed back the better the bus i allways say.

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Old 04-06-2005, 06:38 PM   #2
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You do need to vent the tanks. You can vent through the roof or out the side.
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Old 04-06-2005, 08:02 PM   #3
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I don't have tanks on my bus yet either, but is there any reason you couldn't have a "common" vent for both grey and black tanks? That way you would just have one vent pipe/line going through the roof or side of the bus.
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Old 04-17-2005, 06:55 AM   #4
Join Date: Jan 2005
Location: bossier city La
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Originally Posted by AK-Brando
I don't have tanks on my bus yet either, but is there any reason you couldn't have a "common" vent for both grey and black tanks? That way you would just have one vent pipe/line going through the roof or side of the bus.

i dont see why not as long as the pea traps are in place and have water in them that was my concern with a single vent was that if you bus sat alittle while and you did'nt get you black water tank flushed good and your peatrap on your sink dryed out you would start to smell it in side thats why i am going with two vents.
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Old 04-19-2005, 09:56 AM   #5
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I ran both of mine straight up about 4 feet so the water would not mix while going down the road, then tied them together and only had to cut one hole in the roof - less holes in the roof=less posibilities for leaks.
I do dilegently keep water in the p-trap in the sink and tub.
The grey water tank stinks almost as much as the black........
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Old 04-21-2005, 09:35 AM   #6
Join Date: Mar 2005
Location: Plymouth MA
Posts: 197
No one has answered his question about mounting the toilet to the tank, and I'm curious does it go in? I'll be doing mine later this year, and also want to know.

As for the vent, I guess a common vent exiting the roof is OK, but a good installation whether one or two vents through the roof doesn't matter. If you have a good roof seal, then no leaks.
I'd still worry about gas from the black tank getting back through the common vent line, p-traps or no p-traps. I'm planning separate vent stacks.

A thought comes to mind:
where in the tank you attach the toilet.
I'd think in the CENTER of the tank, as it's in a position to resist surges from driving/stopping the bus. Less pressure, less chance of splash or back flush.


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ALthough I understand slide-outs have their share of problems, It's an interesting solution to space concerns.

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Old 04-22-2005, 09:42 AM   #7
Join Date: Dec 2003
Posts: 245
Of course you need to get all the measurements right …but here’s the condensed version on how to hook up the toilet to your Black tank

1….Toilet Attaches to Closet Flange w/ bolts (don’t install it yet)

2….At the underside of the flange you glue your black pipe section leading down to the black tank (holding tank)
But don’t glue it to the flange until you get your tank setup to receive the pipe.

3….using a hole saw attachment on your drill or an exacto knife ….cut out the hole(s) on your tank where the black water pipe & vent pipe will enter the tank. Then glue a rubber tank grommets into the holes
This is a good time to cut out the hole where you’ll attach the out-flow parts too. Some tanks are already setup with this hole …but some aren’t.

Since you’re starting from square one here …the easiest way to get everything straight and matching up….is too take a section of pipe(s) ,insert it into the tank grommet (don’t push it into the tank ,just let it sit on the ‘shelf’ built into the grommet)…then boost it up under the rig making sure the pipe enters the rig and then either temporarily attach the holding tank to the bus …run back inside and mark the point on the pipe where you’ll need to cut it down to the correct size …or hold the tank up flush to the underside of the bus and have a friend make that mark.
NOTE: this measurement part of the process is the most important detail. You really have to make sure the pipe is centered in the hole as much as humanely possible…if you don’t get this part right nothings going to fit later.

Taking into account the thickness of the floor flange cut the pipe down to the correct size.
Now you can glue that pipe section to the underside of the floor flange (closet flange)…you can also get the flanges where you screw the pipe into them if you’d like.
Attach the floor flange by placing it in the correct spot with the pipe centered as much as possible …and use a pencil or whatever to mark where you’ll drill out the attachment holes.
If you temporarily attached the holding tank …remove it.
Now drill through the floor all the holes you marked out and bolt the flange securely down.
After the flange install is done …
Re-attach the tank to the rig and you should have a nice strong & tight installation.
Note: you don’t glue the pipes where they enter the grommets on the tank …just let then sit firmly on the ‘shelf’ in the grommet for a good seal.

Note: most RV supply places have the parts necessary for building the Black water system….the rubber tank grommets cost around $3.00 -$5.00 a pop

As far as where to locate the hole in the tanks….most installs go for either the center or toward the rear.
Also….Some motor homes and trailer go for a common vent pipe …but I prefer separate ones. I just like standalone systems that can be worked on without affecting the other systems…

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Old 04-18-2015, 03:19 PM   #8
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Studor vent or island vent will solve the solution of a hole in the roof it work's for my 4-person family? I have seperate tank's for each but if you use a box of limestone rock's to drain the grey water into it I can dump it straight to the grass/dirt and I am willing to challenge any inspector or environmental engineer!! Bag of LIMESTONE hardware store 4 $ replace as needed?
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Old 04-18-2015, 05:57 PM   #9
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Works great in summer. Works not-so-great in winter when it turns into a giant ice block. Best for temperate locations. ;)
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