Flexible water tanks

[Jimlad]

One of the four Stainless watertanks on my boat sprang a leak yesterday.
As all of them are now over 30 years old (and the 2 similar fuel tanks!) I am considering replacement with flexible tanks.
My question is as all 4 watertanks feed to a common manifold connected to the 1st tank which fills from the deck filler will I still be able to use this arrangement, as two two aft tanks are higher than the two forard tanks which are under the settee berths to port and starboard??
Any comments/advice out there?

[David M]

You can get HDPE (High Density Polyethylene) tanks in all kinds of shapes and sizes...not just rectangles. I had the same situation as you a number of years ago where the seams on my stainless steel tanks on a boat built in 1975 started leaking.

The stainless tanks were custom shaped tanks that fit very well maximizing how much water they could store. I was surprised when I found some HDPE tanks that came relatively close to filling the same space as well as the stainless tanks did. I don't remember which supplier, since this was a number of years ago, but there is at least one company that can make custom shaped (welded) HDPE tanks, just in case you can't find anything that comes close enough. There are a lot more shapes and sizes than what West Marine has to offer. I found them by doing a Google search.

I would imagine rigid tanks are going to be more durable having a thicker wall combined with the fact that they will not chafe if secured properly.

[HopCar]

I agree with David. Check the Ronco website to see if they have a size and shape that will work. Ronco makes about 500 different tanks.
Here is a link: Ronco Plastics - Marine Water Tanks, RV Water Tank, Auto Detail Tanks, Water Tanks

[Jimlad]

Thanks for the links guys - Trouble is the boat is in Spain.
Could ship HDPE tanks from the UK I guess.

Still thinking about flexi tanks, due to easier shipping if I have to import them.

My question about linking 4 of these via a common manifold still stands, as the tanks empty presumably the two higher ones will collapse and empty first so should I fill these first? If so I will need to install a new deck filler presumably?