Question: Recently I discovered that the aluminum potable water tank on my boat was leaking. After inspecting it closely I discovered that the tank had a lot of corrosion on its outer surface and in general is in pretty bad shape. So, the plan is to replace it over the winter. I’ve read here on boats.com that aluminum is not approved by the ABYC for use with potable water tanks, so now’s the time to get it out of the boat and upgrade into compliance with industry standards. Since the shape of the tank is a little out of the ordinary I have been thinking of making a replacement tank myself out of plywood-cored fiberglass. Is there anything about this idea that I need to know about in terms of industry standards compliance?
Answer: The article you’re referring to is Aluminum Water Tanks: Safe to Use? And the answer is, you’re right, getting rid of your old aluminum potable water tank is a good idea. As for the use of fiberglass to make a new tank, you probably want to check pricing on a pre-made polyethylene tank if you haven’t already. It may be quite a bit less expensive than the cost of materials for a hand-made fiberglass tank. You do mention however that your tank is an odd shape, and that in itself could be the deal breaker because the available pre-made tanks are pretty standardized in terms of shape, which might limit your ability to maximize your storage capacity.
So, if fiberglass is the only option, the only thing you need to think about is the resin you select. Fiberglass storage tanks are widely used in the chemical and food industries to store various products. For food products, the FDA (U.S. Food and Drug Administration) weighs in. Any resin used in the manufacture of food product storage needs to be FDA-approved. The ABYC mirrors this requirement in its potable water standard H-23.
So, now where do you get this FDA-approved resin? Typically you won’t find what you need at your local marine supply store. That said, a search online will provide plenty of information on sources for the approved resin. One good source is Mertons.com.