West,

Get the tank that fits just right and is as big as you can make it. Then, install one of the low cost PUR water filters! They work GREAT and last a LONG time. You can take a couple of extra filters and go for a year or more. Ours last about 4 to 5 months each. And we have NEVER suffered ANY bad water tastes or "tummy troubles". I have even fir one to a foot pumped water system on a small older boat I had. The one in the photo below is the one we like the best.

Standard disclaimer, not connected just a satisfied user.

Greg