Building Watertanks

[chowdan]

Hey all,

Well as the title says, I am going to be building a water tank.

After receiving different quotes for a number of materials, and a talking to makers about different designs that are off the shelf, it seems like going with a custom made fiberglass tank is the wisest choice financially and more importantly - for tankage size.

I see a lot of information out there about "there are plenty of food grade epoxy coatings on the market" but I am having a difficult time sourcing and finding them.

I am planning to build the tank out of 1/4" marine ply, nailing it all together with a nailgun, then epoxying the entire interior/exterior with some 6oz cloth - probably 2-3 layers. All joints will have tapes seams with biaxial cloth. I'll put in a few baffles as well.

That being said, does anyone have any recommendations on possible food grade epoxy and epoxy coatings?

I am leaning towards west systems and then some sort of interior epoxy coating for water tanks, but again, I am unsure of brands that are food safe :\

[slug]

I recently saw a custom grey water tank being constructed

They used sheets of G 10 , epoxy fillet on inside and all structural reinforcement and hand glasswork on the outside

The beauty of the technique is that the sheets of G 10 are perfectly smooth

No , or very little inside tank filling , sanding fairing was needed

I assume the sheets were normal g10

For tank coating you should consult an industrial paint companies web site

International , sherwin Williams

[billknny]

Let's see, I want "food grade epoxy" I wonder where I can find such a thing...

Lets try google, "Food grade epoxy"

Presto.... https://www.resoltech.com/en/markets...al-detail.html

This stuff has the advantage you can use it not just as the final coating but as the resin in the glass reinforcing layers too.

You do have to be careful there are a lot of epoxy coatings rated for "incidental" food contact, like a coating on a table the food MIGHT touch, but the full immersion coatings are harder to find.

While G10 is amazing stuff, and I'd not hesitate using it for a holding tank, but for potable water contact? Not so much... It is epoxy (or sometimes phenolic resin) that is not rated for food contact.

[slug]

You will need an inside coating

And as I recommended .....Google sherwin Williams or international paints and you will find many food industry coating

https://industrial.sherwin-williams.....10656398.html

[coopec43]

I think you are going about it the wrong way.

I built female molds, used polyester resin and gave them a coating of water based bitumen which has been approved for water storage by the WHO(?)

You might be able to buy Food Grade Epoxy but can you cure it correctly? West System (Gougeon Bros recommend against its' use as there is no way an amateur can control temperature, humidity(?) etc. There is an article on the internet where they say their epoxy is not suitable for amateur construction of water tanks. This is not the actual article but.


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

We have adopted the broad policy of not recommending epoxy for drinking water tanks because of regulatory and safety issues. The potent..........

https://www.epoxyworks.com/index.php...nk-guidelines/

[laika]

I used a product called brewcoat on my integral tanks. Some of this might be useful..

https://www.cruisersforum.com/forums...ks-149801.html

[coopec43]

Originally Posted by laika

I used a product called brewcoat on my integral tanks. Some of this might be useful..

https://www.cruisersforum.com/forums...ks-149801.html

Do you reckon an amateur could get a good cure with make-shift facilities?

I've seen this question the subject of several different forums and often people state they "have been drinking water out of epoxy tanks for the last 30 years and have had no problems".

Of course there are many smokers still around after smoking for 30 years!!

A commonly used polymer is epoxy resin consisting of monomer bisphenol A (BPA). Leaching of BPA from epoxy lining to drinking water has been a concern among public and authorities. Currently epoxy lining is not recommended in some countries.

https://www.researchgate.net/publication/305384246_Drinking_water_contaminants_from_epoxy_r esin-coated_pipes_A_field_study

[Pauls]

PPG is a major world manufacturer of industrial grade paints. They have several designed and marketed for potable water. The world is full of large potable water tanks. This is very well developed territory, you do not need to be experimental.

https://www.ppgpmc.com/protective/wa...water/products

[coopec43]

Originally Posted by Pauls

PPG is a major world manufacturer of industrial grade paints. They have several designed and marketed for potable water. The world is full of large potable water tanks. This is very well developed territory, you do not need to be experimental.

https://www.ppgpmc.com/protective/wa...water/products

When I was about to build my tanks I told the resin supplier what I planned to do -build the tanks integral by using the hull as part of the tank. He said "NO! You go to someone who specializes in potable tank coating".

I had a phone call from the "expert" and I told him I wanted to build an integral water tank in the bilge. He said "I'm a bit worried about the coating curing. How much sun will it get?"

I finished up using Crommelins Water based bitumen

http://www.crommelin.com.au/assets/Uploads/TDS-Water-Based-Bitumen-Paint.pdf

[Uncle Bob]

Originally Posted by coopec43

When I was about to build my tanks I told the resin supplier what I planned to do -build the tanks integral by using the hull as part of the tank. He said "NO! You go to someone who specializes in potable tank coating".

I had a phone call from the "expert" and I told him I wanted to build an integral water tank in the bilge. He said "I'm a bit worried about the coating curing. How much sun will it get?"

I finished up using Crommelins Water based bitumen

http://www.crommelin.com.au/assets/Uploads/TDS-Water-Based-Bitumen-Paint.pdf

From your link.
Water Based Bitumen Paint is suitable for use on the following surfaces:
• Concrete & Brick. • Timber Posts. • Plywood Sheeting.
• Cement Sheeting. • Steel. • Aluminium.
How did your expert feel about fibreglass?

[Pauls]

If you want to pay attention to "experts" then I suggest you read the TDS (Technical Data Sheet) for the paint/coating you intend to use. Any professional level coating will describe, in detail, what materials it is meant to be applied to, how they should be prepared, how to apply and cure the material, etc. You can call the manufacturer and speak to one of their technical support engineers. Go to the source. Again, I have found PPG to be helpful and knowledgeable.

[Jammer]

Many of the products previously available have been discontinued or reformulated to meet VOC requirements or are no longer recommended for potable water due to increasing concerns about residual BPA.

Here is one of the few I could find. It is not recommended for potable water tanks smaller than 3000 gallons because of the ratio of surface area to volume, however, and is only available in 5 gallon containers, which is probably much more than you need. I have previously used a related product that is now discontinued.

https://www.rustoleum.com/product-ca...ow-temp-epoxy/

Maybe that will give you some ideas at least.


Any water tank or piping material will leach chemicals into the water to some degree.


A fact to consider is that a carbon block filter will remove most organic contaminants.

[Chotu]

This nut is too big to crack. I was trying to do the same thing. It's just not worth the time, money and health risks involved.

Get a polyethylene water tank and make it fit. You'll be very happy you did.

[Pete7]

Originally Posted by coopec43

I think you are going about it the wrong way.

I built female molds, used polyester resin and gave them a coating of water based bitumen which has been approved for water storage by the WHO(?)

Interesting, for the final tank did you use gelcoat first for the inside then paint or just paint the fiber glass?

Pete

[coopec43]

Don't forget flexible water tanks.

https://www.arnoldsboatshop.com.au/w...waAgJpEALw_wcB