Gray water drainage design help (see drawing)

[evy]

Hi everyone,

I'm working on my very first DIY camper conversion, using a 2010 extended Ford E250.

I'm trying to plan out my gray water sewage system, I want to keep everything above the floor in the heated area. I want to have these options :
A : gray water holding tank
B : flexible hose from my camper to camping site sewers
C : directly to the outside ground

As you can see in my floor plan, my biggest problem is that I have the center aisle between the shower and the kitchen sink...

I thought of using a small automatic 12v bilge pump to pump the shower's gray water over the center aisle into the holding tank under the kitchen sink. The specs for the bilge pump : 750gph, 12volt, 3amp draw, 3/4" outlet, 28$.

When I decide not to use the gray water tank and dump the water outside (either in the sewer or on the ground) I simply remove the plug from the drain inside the pump's temporary tank, the water is drained directly outside so the pump never comes on.

Please let me know what you think or any advice what so ever, I have no experience, I'm only using my logic.

[evy]

Anyone...

[evy]

Also I'm worried about how the tank is going to react when full, for example if I bolt the blade valve to the tank, I will probably have to also strap down the TY arrangement under the van.
When the tank is full it might balloon and change the angle and put stress on the joints because the arrangement under the van won't follow... hard to explain

[evy]

Hi guys.
Ok so I made a video of how I'm thinking of hooking up the grey tank to the outside flexible hose.

https://youtu.be/a8dXU4ZRS6U

A few things I forgot to mention in my video :
-I can't add the blade valve underneath the tank because I wont have access to the handle and because there's is a cross beam right under the tank's floor.
-I don't want to add the valve under the van because it would risk freezing.

[evy]

So I got my 18G grey water tank, it's a tight fit underneath the sink 😕

I will cut the 5/8" thick plywood underneath the tank.
I will also try to find a shallow sink strainer assembly, mine is too deep.
and finally I could add a flexible P trap?

[evy]

Hey guys, I'm trying to buy the pipes and fitting and I can't seem to figure out what kind of fitting go on top of the tank (3/4" vent and 1-1/2" sink drain)? Do I just drill a hole with my hole saw and insert my pipe in the hole? with silicone around the pipe?

My tank is not an ABS tank, it's actually a clean water tank, white plastic with one 1-1/4" tap and three 1/2" tap on top, can I use one 1/2" tap to vent the tank?

Also I have a 1-1/2" Valterra ABS blade valve directly on the bottom of the tank, do I simple use silicone between the ABS and white plastic tank?

[CJW8]

Pump and check valves will quickly foul with hair.

[04fxsts]

The bayonet fittings are not necessarily interchangeable! I just found a leak in the grey water valve and found the pipe flange to have an ear broken off. When I took the other 3 bolts out Icould see it had allways been in a slight bind. Went to the local TT sales and they fixed mr up with the needed repair parts. Every thing looked the same but then I found the new valve flange has a slightly different bolt pattern. They also have a different diameter boss where the seal to the valve sits. Valterra is the brand of the replacement parts and the origonals aredifferent. I can't remember the brand except it starts with a "B" and it is outside under the MH and I am inside where it is warm . So, make sure you check for compatability between brands. I should get mine straightened out today. Jim.

[evy]

Once again thanks for the reply DrewE :C


I was wondering, what is the best way to design all the inlets/outlets on the campervan? what should be on the left side and what on the right? 3" Sewer connection, city water inlet, electrical inlet etc... vs camping site typical arrangements vs parking the campervan in forward or reverse?

[DrewE]

So far as I know, the bayonet fittings are all interoperable. Some have two prongs/knobs and some have four; the four prong/knob ones are a little more secure, as would be expected. Naturally, the larger the tank the more convenient it is (within reason), but practical matters like available space usually dictate the possible size, at least to some extent.

There's nothing dangerous with having a smaller gray water tank than fresh water tank. It just means the gray water will fill up before the fresh water goes empty. 18 gallons should be enough to last a few days if you conserve water usage a little (navy showers, conservative dishwashing water usage or using disposable dishes/cutlery, etc.). If you happen to be in an area where the water supply is not potable or is safe but not appetizing for whatever reason it's nice to have a comparatively large fresh water tank. Do ensure that your shower pan has a reasonable threshhold on it so that you won't flood out the entire van if you accidentally start to overfill the tank. (The shower drain, being the lowest opening in the system, is where it would back up first.)

[evy]

Another quick question for you guys, are 3"diam bayonet fittings universal? Can I buy a fitting from valterra and another from Jr Products or Camco etc... and their won't be any dripping? or I have to stick with the same brand?

[evy]

I just checked some Roadtrek specs on their campervan's and it's around 32gal(water tank) and 23gal(grey water tank) so I guess I'm not far off, but I want to know if it will be a PITA or not? from you experienced campers out there.

[evy]

Quick question, I have an 30 gallon clean water tank already installed under a bench, is it ok if I buy an 18 gallon grey water tank? keep in mind I have a porta potty.

Thanks!

[Bobbo]

In that last drawing, eliminate the top tank completely. Have the sink drain directly into the bottom tank. Have the bottom tank's roof vent do nothing else but vent that tank.

Like DrewE said, you definitely must have a p trap below the shower.

That will be a workable solution.

[DrewE]

TakingThe5th wrote:
Maybe I'm missing something, but is there a way you could somehow tie the drain lines together below the floor while keeping the valves above the floor? With the drain lines coupled you could at least equalize the level in the tanks when necessary and also be able to dump tanks with one hose. If you dump the kitchen first, then the shower, your hose will also be cleaner for stowing.

The shower tank needs to be lower than the shower drain, which is more or less at floor level, ergo the shower tank needs to be below floor level. If there's room enough for a larger tank, there could be a single combined tank below floor level, which would simplify things somewhat and gain some useful cabinet space.

This latest revision actually looks nearly workable to me, at least in the basic overall plan. The connection between the tanks via the vent line is the biggest problem; it should be a separate connection with a valve. With the connections as shown, if water is flowing from the top tank to the bottom tank, the air being displaced from the bottom tank has no ready exit. Also, with no valve, once the bottom tank fills up you can't use the kitchen sink even though the top tank is empty or the shower drain will overflow.

There also needs to be a trap for the shower drain, either one built into the drain itself or a separate P trap underneath. Without it, odors from the tank will enter the RV. (Shower water will get nasty after sitting for a week or so, just like dish water will.)