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Want to modify a fresh water tank.

PostPosted: Wed May 24, 2017 7:28 am
by daveesl77
To begin, our "onboard" fresh water system consists of two, 5 gallon plastic cube type water jugs from wallyworld. I modified the lids and they work ok, giving us 10 gallons feeding into a pressure pump.

With that said, when I did my RV junk yard scavenge almost two years ago, I found a 38 gallon, standard RV, fresh water tank and got it for $10. It has been sitting on a shelf, fully cleaned and sealed, since I got it. And that drives me crazy. Here is a perfectly good, but admittedly very large water tank and it does nothing but sit on a shelf. So my thought is to modify it, to cut it down to say, 10 gallons or maybe a bit more. Its circumference measurement fits perfectly in the space where I presently keep the two water jugs, it is just really long.

So, the idea is to cut it down, then to seal the end up to make it a smaller tank. Does anyone know the proper way to "weld" one of those white plastic (I assume poly) water tanks? Or am I asking for trouble?

dave

Re: Want to modify a fresh water tank.

PostPosted: Wed May 24, 2017 9:37 am
by Nobody
Dunno exactly what you have but, in my experience most fresh water tanks that are not metal, are made of some kind of polyethylene or polypropylene. Neither accepts adhesive very well. Most poly items are bonded with heat using special, item specific bonding methods/equipment. If you aren't set-up to bond the particular tank you have, I think I'd either use it as is or try to sell it to someone that might be able to use it. I don't personally know of any adhesive that works effectively with poly material... We've used a 7gal square, Aqua-tainer from WalMart successfully for over 10yrs. Just refill it when necessary.

If you can acquire a commercial grade 'plastic' welder, you MIGHT be able to achieve a suitable joint. I'm not sure I'd trust it with water tho. That's a lot of weight (10 Gal + approx 82lbs) especially sloshing around when only partially full. I think you may just be asking for trouble but than again, I've never been particularly adventurous when it comes to things I'm not really qualified for.

Good luck on whatever you decide.

Re: Want to modify a fresh water tank.

PostPosted: Wed May 24, 2017 6:16 pm
by Shadow Catcher
I have not done it my self but a proper plastic weld is as strong as the original tank. The question is will you save any money.
The Harbor Freight welder is $50, with some risk in can you get it right , I do not know if I would trust my own work and I know how to weld. You can look for a plastic welder in your area, there are a couple in the Toledo area.
The other alternative buy a new one, search RV water tanks some in the $50 and you can specify inlets etc. Try Ebay one 10 gal at 33.79 with shipping.

Re: Want to modify a fresh water tank.

PostPosted: Wed May 24, 2017 8:43 pm
by lrrowe
I had a serious lapse in good sense awhile back and screwed a screw through a wall right into my plastic water tank. And I did not catch this problem (leak) until my a recent outing to First Landing, VA. I plugged it using a heat source (propane touch). I to gently melted the plastic around the hole with the touch. The plastic would melt, but not fill in the hole. I ended up using of all things, an archery arrow flecthing melt stick and plugged the hole. It seemed to hold up well enough through the tests I ran. I also using a larger piece of plastic sheet to cover the whole side and used silicone sealant as a cement.

I use this explanation as a small encouragement that you can fuse the plastic together.

Re: Want to modify a fresh water tank.

PostPosted: Thu May 25, 2017 12:05 am
by MtnDon
Build a bigger trailer for it. :lol:

Re: Want to modify a fresh water tank.

PostPosted: Thu May 25, 2017 6:57 am
by daveesl77
MtnDon, perfect answer! ha ha.

I wasn't sure if anyone knew some trick to doing something like this or not. The original idea was that I would carry it in my truck bed and if going somewhere that would have very limited access to water I could fill the entire tank and be able to go for many, many days. Truck is gone now, and while it would easily fit in the van, the physical size is just too big for what I want.

Wife to me when I brought it home - "Why did you buy that thing?"

Me to wife - "But it only cost $10 and look how much water it can hold"

W2M - "Where are you going to put it?"

M2W - "I don't know, but it only cost $10"

:D

dave

Re: Want to modify a fresh water tank.

PostPosted: Thu May 25, 2017 7:05 am
by lrrowe
If you were closer to me, I would offer to buy it from you. That size would fit my plan to carry extra water in my truck and pump it to my CT tank when going off the grid.