is fiberglass a suitable material for potable water tanks?

gastonanthony · Post by **gastonanthony** » Fri Oct 10, 2008 1:19 pm

does anyone of you guys know if a fiberglass tank made of polyvinyl ester resin safe for drinking water? i've been hearing about all these stuff saying that polyvinyl ester is toxic and not suitable for water storage etc.... please help, i can't start with my water tank project because of all these worries...should i line the interior of the tank with other resins/materials? how dangerous is polyvinyl ester ?

Post by **Tim** » Fri Oct 10, 2008 2:01 pm

At a bare minimum, styrene-based resins (like polyester and vinylester) tend to leave a "taste" in water that is stored in tanks made of these materials. Potential toxicity (or not) aside, the water just doesn't taste or smell good.

Taste aside, I'd not take a chance on a composite potable water tank--polyester, vinylester, or epoxy. There are just unresolved questions about the potential toxicity of these products when related to potable water. Stainless steel is the premium choice for water tanks, in my opinion.

Here is an article concerning the use of epoxy resins for water tank construction that you may find relevant. If nothing else, it's more grist for the mill as you contemplate how to proceed.

Building Tanks with West System Epoxy (From Epoxyworks Online)

Here is a relevant quote from the article, which I'd suggest would apply to tanks built out of any sort of resin:

West System Epoxyworks Magazine Article wrote: Considerations for potable water tanks
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.

Finally, note that the suggestion that composite potable water tanks are a "suitable" choice is conspicuously absent from ABYC H-23.6, which does not include fiberglass or composite of any type in its "acceptable" list.

Idon84 · Post by **Idon84** » Fri Oct 10, 2008 6:44 pm

When we bought our boat it had water tanks built into the keel. They were no longer usable due to osmosis inside the hull leaving a nasty black film in where the hull was blistering inside. Never got a chance to taste the water in them. I toiled over rebuilding or replacing and read a few articles one just like the one Tim mentioned. I decided to have tanks built.

I agree that Stainless is the prefered "PREMIUM" material but after some investigation I decided to save some cash and try custom polypropylene at Triple M Plastics, http://www.triplemplastics.com Only time will tell how well they last and how comparable they are to stainless. I am happy how the tanks turned out, they are sturdy and overbuilt, and even more so with Triple M's service.

My 2 tanks, total of about 46 gallons cost about $800. The lowest cost for stainless I got was $2100.

Check out the pictures of the old and the new tanks 3/4 of the way down the pictures at http://picasaweb.google.com/Idon84/CosmicDancerRebuild#

CHEERS!

Idon84 · Post by **Idon84** » Fri Oct 10, 2008 6:53 pm

http://plasticclassicforum.com/viewtopi ... highlight=

ALSO...

Check out the discussion I had with the forum regarding the building of my water tanks.

Post by **Tim** » Sat Oct 11, 2008 7:30 am

Idon84 wrote:Never got a chance to taste the water in them.

Sounds like you really missed out...

CharlieJ · Post by **CharlieJ** » Sat Oct 11, 2008 8:26 am

Yeah- that's a shift from the Gougeon's. Years ago when I built my Cross 35, the first Boatbuilding with epoxy book they published, way back in the early 70s, had details on building fuel and water tanks with epoxy. I did so then- built a diesel tank and a water tank using plywood, glass and epoxy.

Made several coffee cups from half coconut shells also, epoxy lined.

In my current boat ( a Rhodes Meridian) I coated the interior of the poorly built polyester water tank with epoxy, after filleting the corners to make it even possible to clean the thing.

As far as I know the trimaran tanks are still doing well after 25 years, and the tank in our Meridian is quite serviceable.

But you DO have to be careful in the mix- you can't just slop some epoxy together and dump it in, and expect it to work correctly.

I'm sure the change in wording is due to the legal climate in this country, more of a "cover your ass" than before.

I'll continue to build tanks for my own use with epoxy. I wouldn't do so for a customer, for exactly the reasons the Gougeons have changed their suggestions. You will note they don't say "Don't do it" However, I'll also continue to fabricate custom diesel tanks using the epoxy. They are quite workable, and pass insurance surveys.

Triton106 · Post by **Triton106** » Sun Oct 12, 2008 12:48 am

Early model westcoast Tritons have built in water tanks in the bilge (see Ray Alsup's discussion on the condition of his tank - http://www.geocities.com/pegasus256/CURRENT.htm) Needless to say after reading that I was not going to drink the water from my built in tank either. Nevertheless, I feel having the water tank in the bilge is a good design feature. So I thought of various options to make my water tank useful again. One of my ideas was to completely sand it down and recoat it with FDA approved resins. I searched all over the websites and found one sold by a local plastics shop (Tap Plastics). Their high strength ISO resin is actually FDA approved for contact with food (see below).

Tap Plastics MSDS quote: "FDA: Food Packaging Status - The components of this product conform to the compositional requirements of the following sections of the regulations: 21 CFR 177.2420, Polyester resins, cross-linked."

FDA website states: "§ 177.2420 Polyester resins, crosslinked. Cross-linked polyester resins may be safely used as articles or components of articles intended for repeated use in contact with food, in accordance with
the following prescribed conditions..."

When I called Tap Plastics I was told that I should not expect that the tank can be considered safe for storing potable water if I simply coat it with the ISO resin. There are strict procedures that need to be followed rigorously, including specific curing temperature, certain coat thickness, etc... They recommend that I take the tank out and take it to a professional fiberglass tank builder. Well that is obviously out of the question.

Furthermore they told me none of their epoxy resins are FDA approved for food contact. You may be able to find other manufactures that offer FDA approved epoxy resins but be careful and make sure the manufacture or retailer can explain the application procedure to you.

In my own case, I have given up trying to make my bilge tank safe for drinking water for now. Maybe I will just put a bladder tank in there. Making a cusom stainless steel or even polypropylene tank is not in the offing either because I would have to cut out the entire filberglass sole which I just covered up with a teak and holly sole.

Good luck and best regards,

gastonanthony · Post by **gastonanthony** » Sun Oct 12, 2008 9:57 am

i was wondering about what resin to use for the inside coating of my tank, because i read in the website of a water tank manufacturer that they are using an NSF listed resin...apporved for potable water storage... anyone knows about a nsf listed resin?

Triton106 · Post by **Triton106** » Sun Oct 12, 2008 12:05 pm

In my research process I called a number of fiberglass water tank manufacturers and asked them what resins they use and who makes them. I then called the resin manufacturers. In my case the resin manufacturers are sympathetic to my cause but were unable to help me since the minimum quantity they sell is 50 gallon barrels. In one case they were willing to consider 5 gallon containers but it is obviously too much for my needs. That led to my finding of Tap Plastics because they buy the ISO resin from a manufacturer that also makes resins for the commercial water tank manufacturers. However, as I pointed out in the previous posting you have to follow the strict manufacturering procedures. I think if you read the West System notice they say the same thing. Some people don't care as much about the potential risks of drinking the water from the owner made fiberglass tanks. It's a personal decision as West System points out.

Triton 185 · Post by **Triton 185** » Sun Oct 12, 2008 1:44 pm

I have glass tank in my Morgan 46. You can see the tank at this link. http://plasticclassicforum.com/viewtopic.php?t=3232 Scroll down to the bottom pictures.

I thought about using the tank and testing the water periodically by bringing it into a lab. In some ways I like the idea of built in tanks, but prefer to air on the side of caution. I have decided to remove the tank and replace it with two stainless ones. Ouch....that's the price to pay!

Rachel · Post by **Rachel** » Mon Oct 13, 2008 12:27 pm

A while back, I was speaking with Sherwin-Williams about their one products, and while I had them on the phone I asked about the idea of using one of their approved water tank coatings (Tank Clad?) on a boat's built-in fiberglass water tank.

I remember that they advised against it. I believe it had to do with the fact that the p.p.m. of potential toxins in, say, a water-tower full of water vs. a small tank full of water was not comparable. That is to say that in a tank as small as one of ours, there would be proportionally much more "tank wall" in contact with the water, and so leaching toxins would be a higher percentage.

I'm speaking a bit generally above, because I only really remember the gist, which was that it was not going to be a solution. I can't remember for sure if it was their Tank Clad product I was asking about, or another product (my initial investigation was on the Tile Clad, and we went on from there).

I don't usually chime in with such vague information (at least I try not to), but I just wanted to throw in the "walls-to-water" ratio idea when considering using large-scale commercial tank-lining products.

Rachel

gastonanthony · Post by **gastonanthony** » Tue Oct 14, 2008 5:27 am

i'm building a spherical water tank of about 500 liters in volume...i've just recently found out that our polyester resin is already food-grade:D

Rachel · Post by **Rachel** » Tue Oct 14, 2008 8:42 am

Maybe I'm being overly cautious here, but I would make absolutely sure that "food grade" is the same thing as being safe for drinking water to be stored in. Water might leach out chemicals (or whatever) that dry "food" doesn't. I guess I'm just saying that I'd want to find out what "food grade" meant, and how it related to drinking water storage in a small container.

Rachel

gastonanthony · Post by **gastonanthony** » Tue Oct 14, 2008 10:50 am

ok, i'll ask some more people in the industry that makes fiberglass tanks..so far...all the manufacturers based on my research(local and international) uses these food-grade resins for making their tanks...i guess one of the reasons why the authorities gave permission for these fiberglass tanks could be because most people here drinks and cooks with commercial distilled water...
although some manufacturers use a polyethylene or polypropylene injection blown tank and covers it with polyester resin and fiber on the outside, this practice is safe for drinking water right?...i'll do some more research about it...

CharlieJ · Post by **CharlieJ** » Tue Oct 14, 2008 12:21 pm

gastonanthony wrote:..i guess one of the reasons why the authorities gave permission for these fiberglass tanks could be because most people here drinks and cooks with commercial distilled water...

I don't know that that is necessarily true. I know it's not for most of the people I know who sail or short term cruise. And if you are doing several weeks or several months, you certainly aren't gonna be using bottled water- Unless you have a whole lot more money than I do.

We have a bladder tank under the cockpit and a fiberglass tank up under the vee berth- 38 gallons total.. We use them interchangeably and really don't see much difference.

We do use bottles of water. Laura puts 8 or so bottles aboard that we fill from the home tap or marina taps. She uses them as "trim " ballast, stowing where needed to keep the boat balanced.

We don't often use any of those on short cruises.