Persistent Leak at Water Tank Outlet

[Heimhenge]

Just joined this forum and this is my first post. Looks like the perfect community for my question.

I have a 2000 gallon poly water storage tank fed by my well. Well production has been dropping (Arizona drought) and I had to have my tank commercially refilled for the first time in a few years. Shortly after that I discovered the tank was leaking around the outlet fitting. When full, there's around 2.3 PSI at the bottom of the tank, and the outlet fitting hadn't seen that much pressure in awhile.

History: The PVC fitting was the recommended one for a poly tank. It was installed 15 years ago as per instructions in a dry tank. Worked fine for many years and then developed a leak. Probably from tank flex when filling or when it warms up. The tank is shaded by an overhead lattice, but some direct sunlight still gets to the outlet fitting.

My solution was to replace the rigid connection between the tank outlet and the house plumbing with a short length of radiator hose held by stainless hose clamps. That was preemptive to compensate for flex. The leak was where the PVC outlet penetrated the tank. To plug that I used "plumbers epoxy" and molded it around the perimeter of the outlet fitting, as you can see in the photo. Of course, I roughed up the surface of the tank and PVC beforehand. That held fine for years until last week, when the new leak was discovered.

So now I need some advice. FlexSeal is not rated for potable water. Plumbers tape is temporary. Draining the tank and installed a new fitting from the inside is something I really don't want to do. My current plan is to clean off all the calcium carbonate crud, rough up the residual surface, and then apply another layer of plumbers epoxy to reseal it. Won't fill the tank again until it's had plenty time to cure.

If anyone can suggest a better solution it would be most appreciated. Thanks!

 

[Fitter30]

Pvc tank adapter has wide shoulder for a larger diameter gasket. Didn't look further to see if it comes threaded. Would also try to remove the strain on the tank fitting picture looks like it's being pulled down.
www.pvcfittingsonline.com/1-1-4-pvc-tank-adapter-epdm-soc-8170e-012.html?country=US&matchtype=&network=x&device=t&adposition=&keyword=&gad_source=1&gclid=EAIaIQobChMIl5fx6tDLgwMVA0ZHAR0MlQ9pEAQYBCABEgIlG_D_BwE

 

[Sponsor]

 

[John Gayewski]

You need to know what is leaking. Is it a mechanical joint (like threaded joint, gasket joint etc) or is there a welded joint that's leaking. If it's a poly weld nothing will work other than having it welded. Some stuff will work for a while but the bond needs to be permanent like a weld.

Depending of where the actual leak is I would wait until the water is mostly used up and then empty it. Whatever you put on the as far as "plumbers epoxy" (plumbers don't use epoxy to fix leaks) will need to come back off to make a proper repair.

 

[Heimhenge]

Thanks for the insights. The copper plumbing didn't line up exactly with the tank output hole, so l;ast time the tank was empty I added that short length of radiator hose with stainless pipe clamps. It had enough flex to make up for the height difference and figured it would flex along with the tank, preventing strain on the fitting. The fitting was installed with a neoprene gasket on the inside. And yes, it was threaded. Did everything right (or so I thought). And like I said, it all held fine for many years until just recently when I had the storage tank refilled commercially. So I don't think the leak is caused by any downward pull by the radiator hose section ... it was the flex of the fully filled tank that triggered the leak.

At the moment, I'm back to considering FlexSeal. Planning to wait until the leak stops and everything dries out, then cleaning the area for good adhesion. The warning that FlexSeal is not for use on potable water systems doesn't so much worry me since it'll be on the outside of the water system and there will be very little contact between it and the water that flows to the house.

I may have to bite the bullet and completely drain the tank to install a new fitting, but that's a real hassle. I'm gonna give the FlexSeal a try first and see it that works. Unless someone can recommend a better product for this situation?

 

[Heimhenge]

You need to know what is leaking. Is it a mechanical joint (like threaded joint, gasket joint etc) or is there a welded joint that's leaking. If it's a poly weld nothing will work other than having it welded. Some stuff will work for a while but the bond needs to be permanent like a weld.

Depending of where the actual leak is I would wait until the water is mostly used up and then empty it. Whatever you put on the as far as "plumbers epoxy" (plumbers don't use epoxy) will need to come back off to make a proper repair.

Thanks. It appears to be leaking between the "plumbers epoxy" and tank, judging from the calcium carbonate deposits. Hoping that as the pressure drops the leak will self seal. Down to 1.0 psi as of today ... about 700 gallons. FYI, the second smaller line coming out of the tank runs to a psi gauge inside the house. Tells me how much water is in the tank. That line has never leaked, but it's a little lower on the tank so it experiences less flex.

Will be trying straight application of some FlexSeal first just because it's the simpler route. That "plumbers epoxy" was claimed to set up even when in contact with water, so that's why I used it on my first attempt. It should chip off pretty easily, but the tank would need to be empty or I'm sure the leak would start again. Trying to avoid coordinating the refill with the repair, but may have to do that.

 

[Valveman]

The larger fitting doesn't even look like a proper tank adapter. It is hard to seal pressure leak from the outside. Worries about Flex seal on potable water is funny with some of the plumbing being a radiator hose. A good tank adapter will solve the problem but will require draining the tank to install.

 

[Tuttles Revenge]

It is hard to seal pressure leak from the outside.

Impossible to seal it from the outside IMO.. especially with Flex Seal.. May as well patch it with scotch tape.

 

[Heimhenge]

Thanks to all for the input. Never tried the FlexSeal as the leak worsened before I could try it. Was up to a gallon an hour when I decided to just replace the fitting. Plumber had to have an assistant go inside the tank to replace it. $$$ He solved the height mismatch by elevating the copper pipe with a brick, as you can see. Compare this photo to the OP. Much cleaner install, and no leaks after refilling the tank. Problem solved. Lesson learned ... leaks like this are REALLY tough to repair from the outside. Moderator can close this thread.