Painting the inside of a water tank?

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john_morris_uk

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I've searched the forums and I can't find a definitive answer.

I've taken the lid off the water tank of our daughters Pandora. It's a small tank moulded in GRP in the bow of the boat. My first inclination was to give it a scrub out and paint the inside in Epoxy resin to freshen it up and increase the impermeability as I'vegopt complete access while the lid is off. However, there are some old threads that talk about NOT using West Epoxy (of which I've got loads) but a food certified epoxy. Other threads suggest some sort of waterproofing bitumen paint.

Is West Epoxy not recommended on the grounds that it hasn't gone through the food standards agency tests for potable water? Or is there another reason? If not West Epoxy, what's the latest recommendation or suggestion. I don't want to move to a flexible liner.
 
On a boat like that, I would seriously consider not drinking the tank water.
I rarely touch it on 'weekender' boats, it's easy enough to have enough drinking water in 2litre bottles.
If I were refitting such a boat. I'd ensure there was a handy place to store such bottles.

IMHO, tanks are stainless, food grade plastic or only for washing water.
Even for water you are going to wash in, I'd be cautious of epoxy. Some people have developed nasty allergies and so forth from epoxy.
 
john_morris_uk said:
I've searched the forums and I can't find a definitive answer.

I've taken the lid off the water tank of our daughters Pandora. It's a small tank moulded in GRP in the bow of the boat. My first inclination was to give it a scrub out and paint the inside in Epoxy resin to freshen it up and increase the impermeability as I'vegopt complete access while the lid is off. However, there are some old threads that talk about NOT using West Epoxy (of which I've got loads) but a food certified epoxy. Other threads suggest some sort of waterproofing bitumen paint.

Is West Epoxy not recommended on the grounds that it hasn't gone through the food standards agency tests for potable water? Or is there another reason? If not West Epoxy, what's the latest recommendation or suggestion. I don't want to move to a flexible liner.
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Acothane DW Solvent Free Polyurethane
 
There is a product called DeVoe Bar Rust 233-H that is FDA approved for small tanks and pipes so long as the application instructions are adhered to. Some tank liner paints are only approved for really large tanks due to the surface area:tank volume ratio, but this one goes down to 50 gallons, which is probably conservative. I don't know if it's available in the UK but it's a start.

Good piece on construction of internal tanks: Atom Voyages - Integral Watertank Construction
 
Is she planning many multi day trips? If not then convert the storage tank to another locker and bring water onboard in a 10 ltr container.
 
I think she’s resigned to a few bottles of water but it seems silly to have a tank and a tap and a sink and not be able to use them. Reading the links, West System say it is possible to epoxy line with their epoxy (EIGHT COATS!) but in litigious USA they’re not authorising or recommending it. They also suggest ensuring a lower catalyst ratio as its unused catalyst that leeches amines and other potentially nasty chemicals.
On Serendipity we have a charcoal filter. That’s another possibility too.
 
john_morris_uk said:
I think she’s resigned to a few bottles of water but it seems silly to have a tank and a tap and a sink and not be able to use them. Reading the links, West System say it is possible to epoxy line with their epoxy (EIGHT COATS!) but in litigious USA they’re not authorising or recommending it. They also suggest ensuring a lower catalyst ratio as its unused catalyst that leeches amines and other potentially nasty chemicals.
On Serendipity we have a charcoal filter. That’s another possibility too.
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I have a strange arrangement in the galley. Three taps, one salt and fresh (a clever three way valve), one electric pump for the main fresh water tanks, and a hand pump for some 10 ltr containers. I've never used the hand pump as 99.99% of the drinking water onboard gets boiled and the other 0.01% gets diluted with Highland Park.

Perhaps a hand pump arrangement might simply things?
 
Sandy said:
I have a strange arrangement in the galley. Three taps, one salt and fresh (a clever three way valve), one electric pump for the main fresh water tanks, and a hand pump for some 10 ltr containers. I've never used the hand pump as 99.99% of the drinking water onboard gets boiled and the other 0.01% gets diluted with Highland Park.

Perhaps a hand pump arrangement might simply things?
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When I say ‘tap’ I mean hand pump. It’s one of these:

D5D3A6B5-C0DB-4E56-8389-146768F7E2C9.jpeg
Mounted on its side with the outlet twisted round suitably.
 
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A former boat of mine hed 2 x 20L jerry cans right under the sink which fed the hand pump, worked well enough as long as they're secure & not brim full. I could chuck them in the dinghy and go fill them up wherever, something like that arrangement might be better for weight distribution as well.

Sounds like the project is coming on well, she's going to be a sweet wee boat by the sounds of it...:)
 
V1701 said:
A former boat of mine hed 2 x 20L jerry cans right under the sink which fed the hand pump, worked well enough as long as they're secure & not brim full. I could chuck them in the dinghy and go fill them up wherever, something like that arrangement might be better for weight distribution as well.

Sounds like the project is coming on well, she's going to be a sweet wee boat by the sounds of it...:)
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Our first boat was like that. I used to use the jerry can as a seat for rowing the dinghy.
 
Potable epoxy is available at cost

Much less costly but identical is aquarium epoxy paint It’s non toxic as you can imagine from the use and is about £70 for a 5 litre tub I’ve done two boats with this now and several other people I know have used the same

it’s a nice finish and totally taste free and non toxic but if painting at this time of year needs some heat to cure On my first go - also in winter and afloat- I ended up hanging a hairdryer in the keel tank for about 6 hours to get it to cure Still going strong 7 years later
 
V1701 said:
A former boat of mine hed 2 x 20L jerry cans right under the sink which fed the hand pump, worked well enough as long as they're secure & not brim full. I could chuck them in the dinghy and go fill them up wherever, something like that arrangement might be better for weight distribution as well.

Sounds like the project is coming on well, she's going to be a sweet wee boat by the sounds of it...:)
Click to expand...

My old Sonata had similar - a pump which fitted onto the water tank itself. Have searched high and low for similar but have never been able to find one.
 
I have a Plastimo 120l triangular flexible water tank, new still in its box which might fit . Otherwise look at fitting one of the rectangular tanks which are relatively cheap at around £50 for a 50l.
 
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