Best material for water tank

[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!

[more]

1 / fiberglas gelcoat inside
2/ polyethylene

3/ SS

but if possible acess to your tank you can repair your with small inverter welder and 1-2 mm ss electrode

[boatpoker]

Had a leaking weld on an ss water tank when I bought the boat 10 years ago.
Sanded the area with 40 grit and applied three 5" X 5" layers of 6oz. glass cloth with G-flex epoxy and it's been fine ever since ( I think the flex quality is important).

[Don C L]

I've seen black Marine-Tex used in a case like that too and it seemed to be fine.

[Bowdrie]

Above posts have good ideas to try.
If you win the lottery have a new tank made from copper.

[Plumbean]

I looked at doing an integral tank with fiberglass and decided to pass. You get more volume, but have to be careful about materials used. Ended up having a plastic one custom fabricated.

[David Mathis]

G-Flex seems to work on just bout any surface and material. Our 100 gallon water tank cracked due to faulty installation (Someone in the factory screwed up) so the tank was removed. Finding a new tank to fit was not achieved so a custom tank was priced. That led to calling West System and their recommendation to use G-Flex. The tank was repaired following the recommendations then reinstalled after testing. That was two years ago and the tank still has no leaks.

[capt jgw]

Ronco Plastics makes polyethylene tanks for a lot of the boat builders and they've kept all the molds. They probably have one that will fit and they will put in whatever fittings you want wherever you want them. It's the quickest, easiest, and probably cheapest option. They sell through retailers or direct, direct is cheaper.

[SailingHarmonie]

Originally Posted by Bowdrie

Above posts have good ideas to try.
If you win the lottery have a new tank made from copper.

And if you win the BIG lottery you go with Monel...

[capt jgw]

Originally Posted by SailingHarmonie

And if you win the BIG lottery you go with Monel...

The fuel and water tanks in my 1973 Concorde are Monel. Must have been cheaper back then.

[Plumbean]

Originally Posted by capt jgw

Ronco Plastics makes polyethylene tanks for a lot of the boat builders and they've kept all the molds. They probably have one that will fit and they will put in whatever fittings you want wherever you want them. It's the quickest, easiest, and probably cheapest option. They sell through retailers or direct, direct is cheaper.

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).

[Dockhead]

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!

Welded HDPE is the best material, from a company like this one: https://www.tek-tanks.com/. Those are the Rolls Royce of tanks.


But stainless, so long as its 316 and of decent thickness, is fine. A bit of leakage around a weld is easily fixed by welding. Preferable to just sealing as that won't stop the corrosion. If it's 316 then the rewelded seam will self passivate and shouldn't corrode.


You do NOT want to replace an otherwise perfectly good stainless tank. It is a very hard and expensive job.

[Dockhead]

Originally Posted by SailingHarmonie

And if you win the BIG lottery you go with Monel...

The monel tanks I've seen have been too thin. Monel is not immune to corrosion. In my humble opinion HDPE is cheaper and better, easier to make properly really thick, and immune to corrosion.

[BenBowSirocco]

Crosslinked polyethylene is by far the most common tank material used today. It can be molded into custom tanks for a relatively small increase compared to one off the shelf tanks and companies that sell them have huge catalogs to choose from.



HDPE: High Density Polyethylene- is not a crosslinked polyethylene. Its not a bad material by any means! But its simply not nearly as strong as a single molded "crosslinked" tank.



If you look up the differences they are stark:

• 10+ times the environmental stress crack resistance
• 10 times the molecular weight
• 3-5 times the impact and tensile strength

In the real world... A custom welded HDPE tank of adequate wall thickness and support is a damn fine tank! The biggest benefit of a welded tank, versus a molded tank is that baffles can be installed.



If your stainless tank is only leaking a pin-hole, I suggest you explore having it re-welded before replacing it.

[BenBowSirocco]

Originally Posted by more

1 / fiberglas gelcoat inside
2/ polyethylene

3/ SS

but if possible acess to your tank you can repair your with small inverter welder and 1-2 mm ss electrode

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.