Water/holding tanks

[Schmidt Racing]

Gentlemen,
I am in the process of building a truck. I am using a Morgan dry box for the rv part. My ? Is this. When you built your trucks, what size of fresh, grey, and black water tanks did you use? I would like to carry 75-100 gal fresh water. Where did you purchase them? Were they custom built or did you just adapt to the size and shape available? I am trying to get large enough tanks and not use all of my underneath storage. Thanks for your input..
Dick

[Bob86ZZ4]

My truck has 2 x 100 gallon fresh water tanks. 75 gallon gray and 25 gallon black. I bought mine used so had no input into the sizing. The gray and black tanks seem to be about the right ratio. When the black is getting full I dump. Only once did my gray fill up before the black. When the gray fills up it comes into the shower. Black is easy to see how full, look down the toilet with a flashlight. If you're doing 100 fresh I think you'd be fine with a 25 black and 75 gray.

[hot rod]

RV Holding Tanks | Replacement Rv Holding Tanks

They have about any size and shape you can imagine and will put the fittings wherever you want them. Take your wallet.

There is generally a small selection at the rv surplus joints around elkhart, but that is potluck and build the truck around them, particularly where the outlets/fittings end up.

One thought, there should be a ton of headroom in that dry box, you may be able to build the bathroom on a raised platform with the black and gray tanks directly underneath the bathroom on the floor of the box. that way you could use flat rectangular tanks and not have to try to figure where exactly to try to shoehorn them in underneath. And many rv's have the freshwater tank underneath the bed, same reasoning.

Don't forget to think about weight distribution when positioning your tanks, 100 gallons of water = 800# and can affect your balance and axle weights.

[Schmidt Racing]

Ok...Does anyone have an opinion as to what the tanks should be made of???
Fiberglass, ABS, or Poly ??? Does it really matter???
Thanks for any help I can get.
Dick

[asitool]

We've decided to build our own tanks from poly. We're early in the process, (just ordered the material). I'll let you know how they turn out when we've finished the first one! Where are you located?

[Schmidt Racing]

I am in Nebraska. How will put them together??? Some kind of glue? Or will u weld them?

[hot rod]

most of the commercially available tanks in rv's are plastic. I've seen guys fab them out of stainless steel, which sounds expensive. Kenn had the coolest idea and built a water tank out of one of his fuel tanks, check his build thread.

[asitool]

We're planning to weld them. There are several vids on youtube detailing various processes. We plan to use an extrusion welder that heats the work piece and filler material at the same time.

We're in southern California. I would be happy to have you over to the shop if you were closer. In any case I'll post pics of the process and pass along anything we learn along the way.