Fixing Leaking Water Tanks with Gflex Epoxy without removing from boat

[Doug160789]

Hi Everyone,

I found a great solution to fixing my leaking aluminum or plastic water tanks on my 1987 Cataline Classic 41 Sailboat. I started to see puddles on my cockpit floor. Realizing the water was coming from my 250 gal aluminum water tank I opened up my wood teak covering the tank and discovered many pin hole and larger corrosion leaks in my water tank. The tank was one piece and too large to remove and replace. I researched epoxies and other coatings I could use to coat the whole tank and decided on West Systems Gflex epoxy. This can be used on metal and plastics and has great adhesion and flexibility.

I wire brushed my entire water tank and when I did, I opened up some small pin holes turning them into larger holes. I especially saw corrosion along the side welds too forming from inside the tank finally making their way out. probably from using too much Clorox bleach added to my water over the years.

After wire brushing the tank I etched it with an etching solution to clean it all off. I then cut some fiberglass cloth as patches covering over the larger holes extending the cloth to about 3" larger than the holes and applied the Gflex epoxy to the patches and set over the holes. I then used brushes and a thick roller cover and gooped on the Gflex epoxy as thick as I could roll it on. I did this for 3 coatings all over the tank. Be careful because the Gflex epoxy cures slowly and the epoxy will have a tendency to run and move down the tank until it starts to cure. So do not apply and leave it. watch it for a few hours until it thickens enough not to sag. 3 years later i have had no leaks and my water tanks are working great! This GFlex epoxy is absolutely amazing!!!

[deltaten]

OMG, 250 gallons...all in one tank?! How big is yer ship?
That's near enuff to a ton that it doesn't matter if I'm off a few gallon/pounds.

I am glad for you that repairs went well. I did some HDPE assembly using G-flex and 10+ yr on, still OK

[PippaB]

Welcome to CF, great first post

Originally Posted by Doug160789

...This can be used on metal and plastics and has great adhesion and flexibility...

So it has adhesion and flexibility, but what chemicals does it leach into your drinking water? Can't find anything to indicate that it is FDA approved for potable water contact. There are very few coatings that are suitable for drinking water contact, and especially so in 'small' water tanks where the surface area to volume is relatively high and thus the leachate concentration is high.

Your tank is no longer leaking, but now the water in it is poison.

[Jammer]

G/flex is a fantastic product.


I would not be especially concerned about chemical leaching into the water. Given the nature of the repair, it doesn't sound to me as though there is a significant contact area. If the G/flex was properly mixed there will be some BPA leaching into the water but perhaps not enough to matter. If the tank is used for drinking water and BPA leaching is a concern, an activated charcoal filter will take it out.

[coopec43]

Originally Posted by PippaB

Welcome to CF, great first post

So it has adhesion and flexibility, but what chemicals does it leach into your drinking water? Can't find anything to indicate that it is FDA approved for potable water contact. There are very few coatings that are suitable for drinking water contact, and especially so in 'small' water tanks where the surface area to volume is relatively high and thus the leachate concentration is high.

Your tank is no longer leaking, but now the water in it is poison.

I couldn't agree with you more.

Gflex might be a good product for repairing a hull but may not be suitable for water tanks. (The fact that West Systems don't claim it to be suitable for potable water makes me think it is not)

You have been using it for 3 years and it obviously hasn't killed you but....

BPA exposure may also influence gene expression, leading to an increased risk of disease. In children, BPA has been linked to poor brain development and behavioral problems, resulting in anxiety, depression, and learning and behavior conditions like attention deficit hyperactive disorder.26 Sept 2022

AND (Is this still the case?)

"19 Nov 2010 — I have to set a couple things right in this thread - none of the West System products, including G/flex, have FDA or NSF approval for food ..."

https://forums.sailinganarchy.com/th...rience.115912/

[PippaB]

Originally Posted by Jammer

... it doesn't sound to me as though there is a significant contact area...

Originally Posted by Doug160789

..I did this for 3 coatings all over the tank...

And, from the EpoxyWorks blog:

Why we don’t recommend building epoxy composite tanks for potable water

We have adopted the broad policy of not recommending epoxy for drinking water tanks because of regulatory and safety issues. The potential problems outweigh the benefits. To date, none of Gougeon Brothers’ epoxies meet FDA regulations or any other drinking water certified approval. The major long-term concern with any plastic water tank is extractives leaching out in the water. Off-ratio, poorly cured epoxy can release extractives, as noted above. In the fabrication of water tanks and food handling equipment, the successful use of epoxy requires thorough mixing and adequate elevated temperature post-cure to assure the maximum cross-linking and cure of the polymer. These process controls are not always possible with the home-built tank. Unfortunately, neither Gougeon Brothers, Inc. nor any certification agency can verify the level of quality control exercised in the fabrication of the tank.

What about the builder who weighs the risks and decides to go ahead against our recommendation? For the homebuilder it is a personal choice. If you build an epoxy composite tank for potable water, follow the general guidelines noted above; in addition, you may want to install an in-line filter to help remove any possible extracts and odd tastes. Professional builders should understand, again, that there are no formal approvals (awarded or pending) for Gougeon Brother’s epoxy products for use in potable water tanks. Where certification is required, it is usually application-specific. We have looked at the 2000 Title 21 of the Code of Federal Regulations, Part 175.300 (Food and Drug Administration, HHS) and found that the testing is specific for end-use conditions, container sizes, and frequency of use. If you have a specific design/use in mind, it may be appropriate to contact the American or Canadian agency to identify their requirements. As with many things, the care used in the construction of the tank is the key to the overall quality.

I would really hate to see a slightly off-mix, hardener rich epoxy leaching amines into the water, and causing someone to get sensitized. As our poor Chotu would attest, amine sensitivity is not fun when working on modern boats and removes a whole lot of potential solutions.

[coopec43]

To make the tank safe the internal surfaces should be coated with Crommelins Water Based Bitumen (or similar product)

Water Based Bitumen Paint
• Non-exposed waterproofing membrane
• Excellent substrate adhesion
• Suitable for planter boxes, pots and water tanks
• Potable water safe
Coverage: 1.5m2 per litre, 2 coats
Recoat/Cure time: 2-4 Hours / 7 Day

https://2ecffd01e1ab3e9383f0-07db7b9624bbdf022e3b5395236d5cf8.ssl.cf4.rackcdn.c om/Product/05c9571f-fb44-4d48-bd0d-06ac21159a9d.pdf