Advice on fresh water tank and gray tank

musigenesis

musigenesis

Senior Member
Joined
Jan 17, 2019
Posts
7,033
Location
Philadelphia
As long as things are still moving on the road, I thought I would order the tanks I've been considering. I'm thinking of this for the fresh water:

https://www.ebay.com/itm/42-GALLON-...uck-holding-wash-tiny-concession/182961556910

and this for my gray tank:

https://www.amazon.com/dp/B07NLLQDC1/

I know the gray is supposed to be bigger than the fresh, but I'm constrained by needing to have the gray tank below my sunken tub but not sticking below the skirt, so it has to be a flat kind like this and I can't find a 44 gallon one that will fit (or a 38-gallon fresh water tank).

Is there anything drastically unsuitable about either one of these tanks for a skoolie?
 
Also, what happened to all the cheap plastic urine diverters for DIY "composting" toilets on eBay? Cheapest one I can find now is $50 and it's from England. Am I searching for the wrong things? They're just pressed plastic, I thought they used to be like $15 or so.
 
musigenesis said:
Also, what happened to all the cheap plastic urine diverters for DIY "composting" toilets on eBay? Cheapest one I can find now is $50 and it's from England. Am I searching for the wrong things? They're just pressed plastic, I thought they used to be like $15 or so.
Click to expand...

I built my composting toilet four years ago and found the one from England Was The best choice for us. We saw some US products that were a couple dollars cheaper but we're kind of flimsy and cheap looking.

We have been happy with it.
 
PNW_Steve said:
I built my composting toilet four years ago and found the one from England Was The best choice for us. We saw some US products that were a couple dollars cheaper but we're kind of flimsy and cheap looking.

We have been happy with it.
Click to expand...

My DIY toilet is going to be a little wonky because I'm going to build it over the fuel tank cover. The urine bottle (or whatever I use) will be off to the side rather than a straight drop, so I'm thinking I might use a big plastic funnel and sort of bend the tip off to one side.

Since I already have the plywood for the whole thing, it's kind of cool to think my toilet will cost me the price of a toilet seat and a couple of hinges. And at one point I almost bought a Nature's Head!
 
odd that the grey tank only has two ports. I think you want 3 ideally. Fill, empty and vent. but I suppose you could tee off your fill line and vent through that?
 
musigenesis said:
Anybody? Help! I just want to make sure I'm not buying the VT-365s of the tank world.
Click to expand...
Those tanks look alright to me. I'd always thought the fresh tank should be larger, esp. if you're using a composting toilet. That urine is coming from your fresh tank, after all. I guess I don't understand why the grey should be bigger.

Our grey tank is similar to that one (but with a side outlet). For the inlet of the tank, I drilled a 1 1/2" hole in the top and dropped the PVC drain straight into it. There's a 1/4" gap around the pipe, which acts as the vent. It gets splashy going down the road when the tank is full though. I'd recommend a real vent.
 
Drew Bru said:
I'd always thought the fresh tank should be larger, esp. if you're using a composting toilet. That urine is coming from your fresh tank, after all. I guess I don't understand why the grey should be bigger.
Click to expand...


Urine is produced by water consumed in liquids and also foods. If you ONLY drank water from the fresh tank (i.e. no pre-packaged drinks ... sodas or beer, etc.) and ate only dry foods, then the COMBINED grey and black tanks would approximate the fresh tank capacity, not accounting for evaporation, spillage, respiration, and sweat. I would imagine the answer would be it depends on your diet and consumption of fluids external to the fresh water tank.
 
So I just ordered the 40 gallon gray/black tank, but not the fresh water tank which I'll hold off on for now. I'm hoping that my initial living setup will have electricity and water (but no sewage) so all I'll need for now is the gray tank.

I went to the bus and re-measured the cavity underneath that this is going to go in, and I don't think there's any other tank that would fit in there. The cavity is about 26" wide and just over 60" long so the tank (24.5" x56") will fit almost perfectly, and it has to be no more than 10" tall to fit under the sunken tub.
 
I think I'm going to build my sideway-pointing urine diverter out of some HDPE plastic I have sitting around, either gluing or welding it with a soldering iron. Prototypes in painted cardboard? Yuck.

How well do the urine diverters from England work for ladies?
 
musigenesis said:
I think I'm going to build my sideway-pointing urine diverter out of some HDPE plastic I have sitting around, either gluing or welding it with a soldering iron. Prototypes in painted cardboard? Yuck.

How well do the urine diverters from England work for ladies?
Click to expand...


Is your urine being diverted to the tank, or to a separate bottle?
 
Drew Bru said:
Is your urine being diverted to the tank, or to a separate bottle?
Click to expand...

To a separate bottle. Here's a diagram basically of how the toilet is going over the fuel pipe cover:

DIY toilet diagram 1.png

It's not completely accurate. In mine the edge of the poo box will be at the edge of the cutout for the toilet seat (so no chance of bombing the pipe cover). But it shows how the urine bottle will be offset from the centerline of the seat.
 
Tried an experiment welding some really thin (1/16") LDPE plastic I have. I tacked the pieces together with my soldering iron, then tacked a thin strip of LDPE over the joint for some extra material and welded it along with the iron (I ran the iron down the opposite side of each joint, too).

IMG_0980.png

Looks pretty big in this pic with my foot there.

IMG_0981.png

The joints are waterproof.

IMG_0982.png

I can bend and mangle this thing pretty good and the joints are holding. I may give it a full-on welding bend test later when I grow tired of it.

The main reason I think this might not be a good idea for a urine diverter is that the joint is pretty rough. Like, the kind of surface that would encourage bacterial growth. :nonono:

Still, gives me confidence for plastic-welding on my tub (which is ABS plastic) at least.
 
Last edited:
I am glad you have had success welding with the soldering iron. Each time I have tried it was not a seal and left a lot of black charred plastic in its wake. Perhaps the type of plastic?
 
I think you need to post a vertical cross-section of your potty area. I do not see why the diverter needs to be on the side. Even if it does, the extent off-axis may be alleviated by using plastic tubing.
 
Native said:
I am glad you have had success welding with the soldering iron. Each time I have tried it was not a seal and left a lot of black charred plastic in its wake. Perhaps the type of plastic?
Click to expand...

I think I just got lucky with the material and its match to whatever temperature my soldering iron is at. I got a little bit of charring at the start but then no more, dunno why.
 
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