A Reverse Osmosis Sysytem is best. The reverse-osmosis membrane acts like an very fine filter to create drinkable water from contaminated water.

I GOT THE WHOLE HOUSE FILTERS (2 ) BEFORE MY SOFTENER TO TAKE OUT THE IRON, & THEN I FILTERED THE SUPPLIES TO SINK, ICE MAKERS, & BAR SINK WITH AN ADDITIONAL WHOLE HOUSE FILTER!
PAPER CARTRIDGES IN THE (2) B-4 THE SOFTENER, & A CHARCOAL FOR THE ICE & WATER….
YOU CAN BUY SOME REAL WIZ -BANG CARTRIDGES FOR THIS FILTER DEPENDING ON YOUR NEED!

Aquapure – I’ve been using one for the last 15 years. It doesn’t have a fixed filter (I don’t know of any that do), but if your water is reasonably clean to start with you won’t need to change filters that often.

I get my drinking water from my reverse osmosis / deionizing filter that I use for my aquarium. It gets the water very clean, alot more than other drinking filterrs. I know that home depot sells similar things, but the filters do have to be changed somewhat frequently.