Best material for water tank

[rslifkin]

Originally Posted by BenBowSirocco

Fiberglass can be a good tank- but you need to use very specific resin systems to avoid leaching and be mindful of the cure cycles. Also be sure to properly heat cycle the tank to post cure the resin as provided by the manufacturer.

Whatever you do: DO NOT USE BOATYARD RESIN or standard gelcoat.

Agreed, some attention to materials choices is needed for a fiberglass tank. When I built my fiberglass water tank I used epoxy mixed close to the hardener lean limit, then coated the inside with Aquatapoxy A61. We didn't use the water for consumption until the tank had been sitting with water in it for a few weeks (and it wasn't filled until a few weeks after finishing the build) and it had been flushed out. And our water system has good carbon filtration that should reduce any concern for stuff leaching out of the tank.

[BenBowSirocco]

Originally Posted by rslifkin

Agreed, some attention to materials choices is needed for a fiberglass tank. When I built my fiberglass water tank I used epoxy mixed close to the hardener lean limit, then coated the inside with Aquatapoxy A61. We didn't use the water for consumption until the tank had been sitting with water in it for a few weeks (and it wasn't filled until a few weeks after finishing the build) and it had been flushed out. And our water system has good carbon filtration that should reduce any concern for stuff leaching out of the tank.

Did you do any heat assisted curing cycles?
In the past I have put a hair dryer in the tank (hanging from the access port, with all access ports open) and used an infrared thermometer to test overall temperatures. Most resin manufacturers will give you a temperature they recommend for a "Full Accelerated Cure Temp".

[rslifkin]

Originally Posted by BenBowSirocco

Did you do any heat assisted curing cycles?
In the past I have put a hair dryer in the tank (hanging from the access port, with all access ports open) and used an infrared thermometer to test overall temperatures. Most resin manufacturers will give you a temperature they recommend for a "Full Accelerated Cure Temp".

I did end up heating things up as much as practical (heat lamps, hair dryer, space heaters) when I applied the inner coating (as that stuff is impossibly thick to work with in the cold unless heated), but I wasn't targeting a specific temperature or anything. The tank is baffled and integral to the hull, plus I built it in the middle of winter, so my ability to heat things up was a bit limited. For most of the build I was heating the space as much as practical and had heat lamps on the tank to keep the epoxy from getting too thick and hard to work with.

In my case the tank had a good month to sit and finish curing before any water went into it, plus a few weeks for the water to leach out any initial stuff before I considered it usable. Every surface that could be was also scrubbed with warm water before the top panels of the tank were glassed on.

With the carbon filters in line, we've never noticed any taste or smell at all from the water that would indicate an obvious leaching problem, although I haven't sent samples off for testing.

[Kd9truck]

To all who posted the use of copper, I am not trying to be contrary, or insulting.

In culinary school in the USA it was strongly communicated that copper was not good use in direct contact with consumables. Since that education I have not seen one single copper pot still in use in professional kitchens.
In the NYC area copper is widely removed and replaced in renovation and not used at all in new construction.

This was taken from Heathline.
Potential downsides of copper:
Long-term exposure to high doses of copper may cause copper toxicity, which is characterized by nausea, vomiting, abdominal pain, and diarrhea. It may even lead to liver damage and kidney disease (1Trusted Source, 11Trusted Source).

One way you may develop copper toxicity is by consuming stagnant water that flows through copper-containing pipes, which allow for high quantities of copper to leach into the water (1Trusted Source).

The World Health Organization (WHO) recommends no more than 0.47 mg of copper per cup (2 mg per liter) of water. This ensures that the tolerable upper intake level of 10 mg per day won’t be exceeded (11Trusted Source).

When it comes to water stored in copper containers, even for periods of up to 16 hours, studies show that the amount of leached copper is well below WHO’s safety limits (5Trusted Source, 8Trusted Source).

Still, proponents of the trend suggest that you limit your copper water intake to 3 cups (710 mL) per day.
Copper exposure should be thought of in rate and dose.

[Bowdrie]

Copper is anti-microbial, critters don't live on it.
However, as I suggested a copper tank "if you win the lottery", I suppose that if one did win the lottery and didn't want copper, they could have their tanks and counter tops made of Silver, it's also anti-microbial.
Jeepers, what about all the millions of landlubbers who've been living in houses that were-and-have-been plumbed with copper pipes for decades?

[Kd9truck]

Originally Posted by Bowdrie

Copper is anti-microbial, critters don't live on it.
However, as I suggested a copper tank "if you win the lottery", I suppose that if one did win the lottery and didn't want copper, they could have their tanks and counter tops made of Silver, it's also anti-microbial.
Jeepers, what about all the millions of landlubbers who've been living in houses that were-and-have-been plumbed with copper pipes for decades?

Yes to the anti-microbial it kills things, copper paint anti fouling paint has been very successful the higher the concentration the more successful the paint.

As for its use in indoor plumbing most pipe is coated on the inside with sediment very soon after instillation. It been thought to contribute to a great many Nero-cognitive disorders.

Again not my science and not trying to embarrass anyone, I just feel compelled to point out a potential health risk.

[peghall]

Cross linked PE has a totally different molecular structure and is only used for fuel tanks because petroleum can permeate linear PE. 99% of PE water and holding tanks are LDPE.

Fwiw, I've known several people who've successfully repaired steel -and even aluminum--water tanks using JB Weld.

--Peggie

[more]

Originally Posted by BenBowSirocco

Fiberglass
Whatever you do: DO NOT USE BOATYARD RESIN or standard gelcoat.

i am not crazy to hard work .
but remember couple italian company have fiberglass tank and food storage certificate.

but if i have leaked water tank.
first i try repair on site by tg weld and ss316 1,2 mm electrode. i smal touch finish.

if dont work , i try cold weld with epoxy,putty something
But usually for change tank need destroy wood lot work.

[BenBowSirocco]

Originally Posted by more

i am not crazy to hard work .
but remember couple italian company have fiberglass tank and food storage certificate.

Lots of great companies use fiberglass and resin to make water storage tanks.. but not "boatyard polyester". They use specific resin formulations designed for their product use case- and probably even a specific type of e-glass, to avoid chemical leaching and assure it's a proper food safe product.

But there is zero doubt in my mind, many a sailboat has a boatyard resin water tank and it's not killed anybody directly.. just encourages cancer I suspect through the leaching of byproducts.

[Dave9111]

Stainless is easy to weld.
If you can get a clear shot at the crack, use a portable Tig welder with argon and reweld it in the boat. Harbor freight has a 165 amp DC tig welder on sale for $500. Need a cylinder of Argon. Many welders have similar portable setups. Not expensive compare to boat parts and new tanks.

[TeddyDiver]

Originally Posted by Plumbean

As far as I can tell (and I own a Ronco built tank that is used for a holding tank for my head and have been through their whole catalogue many times) none of the Ronco tanks have baffles in them. So if you are looking for something above say 20 gallons, that starts to become an issue. I ended up going with Triple-M (still waiting on delivery) but also looked at Dura-Weld. They seemed comparable and both get good reviews. Final decision was mostly based on convenience (can pick up locally at Triple-M while I would need to spend a couple of hundred dollars shipping from Dura-Weld).

About baffles, it's about the length of free surface/depth of the fluid. Equal length and depth no need but double the length and it's a must. The other thing is the orientation of the baffles. Production tanks (even custom ones) seem to have them straight wall to wall but more efficent is to angle them some. This makes waves hit on opposite sides of the tank diagonally and reduces sound and stress on the tank.

[lrclough]

I repaired leaks due to weld corrosion in my 30 year old stainless 50 gallon steel water tanks about 4 years ago using West System G-Flex thickened with West #406 adhesive filler.

No leaks after 3 years in the Caribbean and 1 more up north.

The cost of new tanks was over $2,000 apiece.

[betwys1]

Originally Posted by Ribe16

I just discovered that my stainless steel water tank has a small leak due to corrosion around the welding. I still have to inspect it throughly to assess the extent of the damage, but I'm considering the option of getting a new one.
In your experience, what are the best materials and why?
Thanks a lot in advance for your advice!

If you decide to repair your stainless tank, you might want to consider passivating the repair weld (and the others?)
Who needs an activated stainless tank?
Here is an article which advocates electrochemical passivating as environmentally friendly (as contrasted with older methods like nitric acid mixes which are deadly)
https://cougartron.com/blog/top-5-we...%20passivation.

[betwys1]

Originally Posted by Kd9truck

To all who posted the use of copper, I am not trying to be contrary, or insulting.

In culinary school in the USA it was strongly communicated that copper was not good use in direct contact with consumables. Since that education I have not seen one single copper pot still in use in professional kitchens.
In the NYC area copper is widely removed and replaced in renovation and not used at all in new construction.

This was taken from Heathline.
Potential downsides of copper:
Long-term exposure to high doses of copper may cause copper toxicity, which is characterized by nausea, vomiting, abdominal pain, and diarrhea. It may even lead to liver damage and kidney disease (1Trusted Source, 11Trusted Source).

One way you may develop copper toxicity is by consuming stagnant water that flows through copper-containing pipes, which allow for high quantities of copper to leach into the water (1Trusted Source).

The World Health Organization (WHO) recommends no more than 0.47 mg of copper per cup (2 mg per liter) of water. This ensures that the tolerable upper intake level of 10 mg per day won’t be exceeded (11Trusted Source).

When it comes to water stored in copper containers, even for periods of up to 16 hours, studies show that the amount of leached copper is well below WHO’s safety limits (5Trusted Source, 8Trusted Source).

Still, proponents of the trend suggest that you limit your copper water intake to 3 cups (710 mL) per day.
Copper exposure should be thought of in rate and dose.

In French kitchens - and elsewhere, copper cookware is favored but it is invariably tinned on the inner surface. This provides a thick surface that is quite robust, but still needs retinning (not electrolytically) eventually. You are likely to face a charge of around $100 per pan in the US , though it varies with diameter and height

[Nicholson58]

Originally Posted by Ribe16

I just discovered that my stainless steel water tank has a small leak due to corrosion around the welding. I still have to inspect it throughly to assess the extent of the damage, but I'm considering the option of getting a new one.
In your experience, what are the best materials and why?
Thanks a lot in advance for your advice!

My 1984 Camper & Nicholson has Inconel water and fuel tanks. Never an issue. I cleaned them once. The insides are shiny after 39 years.