I started out using a 3 step filterbank to fill my potable tank, but as others have pointed out, with a 0.5 micron final filter it coupled with the low water pressure, it sometimes took 6 hours to fill a 90 gallon tank. I also found that even with the 0.5 filter, I sometimes got a salt taste. Apparently some of the salt molecules are real small. So now I just fill my tank with water through the first 2 stages and use bottled water for drinking and cooking.
We've gotten so used to the bottled water taste, everything else tastes bad. So now we use bottled water almost everywhere. We carry three 2 gallon bottles in the states and add a 5 gallon bottle when in Mexico. Purified water in Mexico is really cheap.