Looking for a water filtration tank for Reverse Osmosis system

[peanut]

I have the in house Whirlpool RO system wher25. The tank is extremely rusty and looking for a replacement.
I can't seem to find a replacement tank online and Whirlpool wants $137 for just the tank.
I can get a complete system from Lowes for around $140+tax.
I'm wondering if anyone has an idea for a 2 gallon tank(or possibly a bit larger) that won't break the bank. Original tank is 1.7gal.
Suggestions, Ideas

 

[HMFIC]

What's it made out of and what kind of fittings?
You might be able to put one together yourself out of a small stainless tank for cheaper?

 

[Okie4570]

Cheap ones on Amazon, fittings available at Lowes.

 

[Osage48]

Could you make one out of 8" PVC? 8" should be about a one gal per foot.

 

[peanut]

I'll measure the fitting this eve.
Pipe is an idea but not sure i can get the volume i'm looking for under cabinet.

 

[Okie4570]

The tank has an air bladder in it, that's what pushes the water back out of the tank to the faucet, I think about 40psi when empty.

 

[KOPBET]

http://www.spectrapure.com/St_tanks.htm

 

[Old Timer]

I have a wher25, and added a second tank to it last year.
With the 4.4 gal tank, ($30) we have never ran out.
http://www.waterfiltersonline.com/tanks.asp

 

[peanut]

Thanks for those links

 

[peanut]

You guys ROCK! i got one from Waterfiltersonline.com on sale. Cheap and quick shipping also.
Thanks so much.