Inflatable water tank safe or not?

[paulieraw]

I have an inflatable water tank on the boat. The water has been in there for about 8 years, I will be emptying it out. What do you use to clean and sterilise your water tanks and how many of you actually drink water from your tank?

In the past I have used bottled for drinking, using the tank for other things, washing up, washing me ect. In reality this feels the same as bottled, its both out of a plastic container and with the need to reduce plastics I would like to rely on my own water supply onboard. But can I trust it if cleaned?

 

[pvb]

If you mean a flexible water tank, these usually have a PVC inner bladder contained in a tough nylon outer bag. Plastimo is a popular brand. You can clean it with ordinary cheap household bleach solution (the very cheapest own-brand stuff with no additives), followed by copious flushing. Or you can use proprietary water treatment tablets (Puritabs, etc). If the inner tank is very bad, it used to be possible to buy new bladders for Plastimo tanks. As for trusting it for drinking, it's as trustworthy as most boat water tanks. If you feel there's a taste, you could fit an inline charcoal filter.

 

[paulieraw]

If you mean a flexible water tank, these usually have a PVC inner bladder contained in a tough nylon outer bag. Plastimo is a popular brand. You can clean it with ordinary cheap household bleach solution (the very cheapest own-brand stuff with no additives), followed by copious flushing. Or you can use proprietary water treatment tablets (Puritabs, etc). If the inner tank is very bad, it used to be possible to buy new bladders for Plastimo tanks. As for trusting it for drinking, it's as trustworthy as most boat water tanks. If you feel there's a taste, you could fit an inline charcoal filter.

Thanks for the reply. When you say household bleach do you mean domestos type bleach or somthing else? Wouldn't that leavfe a long lasting taste?

 

[pvb]

Thanks for the reply. When you say household bleach do you mean domestos type bleach or somthing else? Wouldn't that leavfe a long lasting taste?

No, not Domestos. Use the stuff I suggested, the very cheapest own-brand thin bleach, usually about 30p for a 2 litre bottle. Domestos and similar branded bleaches contain all sorts of additives. Use about a cupful in 100 litres and let it stand for a few hours before emptying and rinsing. If you rinse it thoroughly it won't leave a taste.

https://www.tesco.com/groceries/en-GB/products/260550096

 

[dolabriform]

Hi

The one on my 'new to me' boat had 5 year old water in it, and was green at the bottom. If yours has been there for 8 years I personally wouldn't trust it no matter how much it was cleaned. Replace the inner bladder or if needs be the whole thing, they are fairly cheap.

I installed a new one, new hoses etc and I use puriclean tablets. I also have an inline Jabsco Aqua Filter which removes chlorine etc.

 

[paulieraw]

No, not Domestos. Use the stuff I suggested, the very cheapest own-brand thin bleach, usually about 30p for a 2 litre bottle. Domestos and similar branded bleaches contain all sorts of additives. Use about a cupful in 100 litres and let it stand for a few hours before emptying and rinsing. If you rinse it thoroughly it won't leave a taste.

https://www.tesco.com/groceries/en-GB/products/260550096

Makes sense thanks.

 

[paulieraw]

I like the idea of an aqua filter will get one of those

 

[VicS]

If you mean a flexible water tank, these usually have a PVC inner bladder contained in a tough nylon outer bag. Plastimo is a popular brand. You can clean it with ordinary cheap household bleach solution (the very cheapest own-brand stuff with no additives), followed by copious flushing. Or you can use proprietary water treatment tablets (Puritabs, etc). If the inner tank is very bad, it used to be possible to buy new bladders for Plastimo tanks. As for trusting it for drinking, it's as trustworthy as most boat water tanks. If you feel there's a taste, you could fit an inline charcoal filter.

I think you will find that Plastimo advise against using hypochlorite based cleaning solutions !

They supply Aqua Clean which contains Troclosene sodium ( aka sodium dichloroisocyanurate ) as do, I think, Puritabs

 

[dolabriform]

I think you will find that Plastimo advise against using hypochlorite based cleaning solutions !

They supply Aqua Clean which contains Troclosene sodium ( aka sodium dichloroisocyanurate ) as do, I think, Puritabs

ooo, thanks VIc, I'll check what I've got on board

 

[VicS]

I have not the faintest idea why Plastimo advise against hypochlorite

I always use Milton solution for my small flexible tank.

 

[No Regrets]

Milton would be the preferred choice of bleach.

Costs may dictate otherwise

 

[pvb]

I think you will find that Plastimo advise against using hypochlorite based cleaning solutions !

They supply Aqua Clean which contains Troclosene sodium ( aka sodium dichloroisocyanurate ) as do, I think, Puritabs

I have not the faintest idea why Plastimo advise against hypochlorite

I always use Milton solution for my small flexible tank.

They probably would rather people use their own stuff, which is far more expensive than cheap bleach. Diluted hypochlorite bleach won't damage the PVC bladder, after all the Milton you use is hypochlorite-based.

 

[Ric]

FWIW, I recently glassed in one of my saloon lockers to make a hard tank. I no longer needed the plastimo soft tank that had resided there for 15 years. I cut it open before throwing it away - it was immaculately clean apart from a small amount of sediment. It has only ever been filled with French or Italian dock water and I have only occasionally added a bit of dilute household bleach at the beginning of seasons for a rinse.

 

[thinwater]

I think you will find that Plastimo advise against using hypochlorite based cleaning solutions !

They supply Aqua Clean which contains Troclosene sodium ( aka sodium dichloroisocyanurate ) as do, I think, Puritabs

The active ingredient in solution is the hypochlorite ion in both cases. The isocyanate serves to stabilize the release over time. It is used in swimming pools for this reason (keeps the chlorine from quickly volatilizing). It also reduces aluminum corrosion.

Milton is also Troclosene, from what I remember. Again, the main advantage is that it is stable longer, giving it better penetration.

But I doubt the long term effect on plastics is much different.

The other thing to remember is NOT to over concentrate the bleach. Very little is needed, and the more you add, the LESS effective it becomes (pH drop changes the hypoclorite equilibrium--Google it).

 

[Daydream believer]

I have a stainless steel tank & do not drink directly from it , inspite of using aqua tabs etc . This is because I fill up at a range of marinas & somehow I am a bit wary of what i am putting into the tank even after I have first cleaned it.

 

[Daydream believer]

FWIW, I recently glassed in one of my saloon lockers to make a hard tank.

Interesting. I recently suggested to an owner that he lined his existing leaky tank with West epoxy. I even quoted from the Gougeon Brothers book on the West System giving the exact page on how to do it. The book was published in 1979.
When the owner contacted West for further advice they said that they no longer recommended the practice as it had been found that their resin would leach harmful chemicals into the water.
I was surprised at this, so i contacted the makers of SP resins & they also confirmed that their epoxy was unsuitable for storage of water designated for human consumption
They did, however,advise that there were special resins available but they did not make them

So may i ask-- What resin did you use please
thanks

 

[Momac]

Milton would be the preferred choice of bleach.

Costs may dictate otherwise

Milton isn't exactly expensive - about £2 per litre
However this is cheaper ...........
http://www.poundland.co.uk/dr-johnsons-sterilising-fluid-1-litre
I have used the 1 litre in 250 litres of water.

Even cheaper - People have advised a full flush with fresh tap water should be sufficient

Regardless of treatment I try not to drink tank water and prefer to refill 5 litre containers from a mains supply .

 

[maby]

I've always drunk tank water and I'm still alive - no frequent stomach infections either. I do add Aqua Clean Tabs every time I fill up the tank.

 

[VicS]

The active ingredient in solution is the hypochlorite ion in both cases. The isocyanate serves to stabilize the release over time. It is used in swimming pools for this reason (keeps the chlorine from quickly volatilizing). It also reduces aluminum corrosion.

Milton is also Troclosene, from what I remember. Again, the main advantage is that it is stable longer, giving it better penetration.

But I doubt the long term effect on plastics is much different.

The other thing to remember is NOT to over concentrate the bleach. Very little is needed, and the more you add, the LESS effective it becomes (pH drop changes the hypoclorite equilibrium--Google it).

No it's sodium hypochlorite

 

[prv]

Our previous boat had a bladder tank like yours, the current one has rotomoulded rigid plastic. In both cases I drink from the tank, but with the bladder it always had a slight hint of plastic so I'd make lemon squash instead of drinking plain water. A glass of water from the rigid tank tastes just like from the kitchen tap at home.

Like yours, our bladder tank had stood for a while, though not 8 years. The inner bladder had visible slime growth in it, so I disposed of it along with the hose to the pump tap at the sink. You can buy new inner bladders for the standard Plastimo tanks, which is what I did and what I'd recommend if yours has had stagnant water in it for nearly a decade.

Pete