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94-D2's avatar
94-D2
Explorer
Oct 31, 2020

FRESH WATER TANK LEAK

I’ve owned my 2017 Big Horn for three years now. This last August, we had a serious red flag fire warning weekend complete with a PGE Public safety Power shut off. In light of that, I filled my fresh water tank (30-40 gallons) in case we needed to evacuate. Following an all clear, I left the tank full, just in case. In October, I pulled the trailer for a week in South Lake Tahoe CA. Perfect weather and full hook ups. Still had a full fresh tank on board. On day 2 of Tahoe, I noticed a rather large fresh water leak from various points in the undercarriage. I assumed the fresh water was leaking and traveling through the coroplast under the trailer. After three days it stopped. I suspected there was a possible crack in the fresh tank since we had a tire tread incident on the road in February, and a slight showing of water at that time. Upon leaving the resort in Tahoe, I found that the 12v pump didn’t not charge the water system while on tank mode. When I got home, I discovered the fresh rank was in fact empty. I never drained it and concluded it drained o it’s own, and whatever damage was suffered from the tire tread incident was greater than expected.

This last week, I removed the coroplast from the undercarriage of the trailer. What I found disappointed me, but I expected it nonetheless. The bits and pieces of the internal workings of this trailer were haphazardly thrown Together by a kindergartner and as it turns out, caused a water leak in the fresh tank by shoddy workmanship that had nothing to do with the tire tread Was hit on the road.

The fresh tank was installed in its usual fashion. A cross member at one end and three steel straps perpendicular to the cross member. As such, water supply inlet/pump draw tube and low drain hose Were installed and plastic welded next to each other at the bottom of the forward facing side of the tank. Upon filling the tank to capacity for the first time and traveling, caused the tank to bulge on the bottom between the steel straps thereby stressing the welds for the inlet supply fitting that was shoddily welded into place. This caused the weld to fail and produced a leak that drained the tank in three days.

This is the way I found the undercarriage after dropping the coroplast.







  • I sort of had the same issue. Basically a poor installation. I replaced the tank myself with a brand new tank. I did not trust that a repair would be permanent or foolproof vs. replacement.
  • blueglide wrote:
    I bought this plastic welder kit a couple years ago and keep it in my rig full time. https://www.polyvance.com/Airless-Welders-1/5700HT/I needed it when I damaged my fresh water tank cresting an unusually steep short slope. It works great and you can also usually find people doing plastic welding/repair in any good size city. The spin weld fittings on your tank can probably be repaired easily since tank is out.


    Thank you. I did a torch weld and got about 98%. Still leaked about an inch or two over night. I ordered the weld kit with the iron so should be able to Do it right. I’m not in a big city area so trying myself. Otherwise, Sacramento is just over an hour away. If someone had a shop suggestion for that Sacramento area that would be awesome!
  • I bought this plastic welder kit a couple years ago and keep it in my rig full time. https://www.polyvance.com/Airless-Welders-1/5700HT/I needed it when I damaged my fresh water tank cresting an unusually steep short slope. It works great and you can also usually find people doing plastic welding/repair in any good size city. The spin weld fittings on your tank can probably be repaired easily since tank is out.
  • The tank is out. The weld at the fitting flange is thin and weak. I found that there is no such thing as a direct replacement tank. They use whatever tank the manufacturer sources and the fittings are custom installed wherever they need them, either on site or spec’ed out. Either way, even if I replaced the tank, I would have to also custom install the fittings and tank monitor, so that renders replacement moot. So, working on that now and cleaning up all the wiring and hoses.
  • JB Weld won't last on that poly tank. The only real fix is to have it plastic welded or replaced. Clean up all your wiring, fix the tank, add some additional support to the tank if needed to avoid repeat of problem in the future, and don't ignore water leaks in the future for most of a year. They don't get better and only make things worse.
  • On the positive side it looks like you have plenty of room for a larger water tank.

    To fix your existing tank you might try letting it dry out really well and then jb weld it.
  • All I see is a lot of sloppy wiring and a whole lot of words.