At home we use the Pur countertop filter that has a separate filter container and connects to a special valve on the faucet with a plastic hose. It lasts about a year at home so would last a lifetime on an RV.
For filtered water you pull out a little slide gizmo on the faucet which runs the water thru the filter. Pushing it back gives you water from the tank for washing dishes, etc.
We like the Pur filter because it filters out a whole bunch of stuff including cryptosporidium germs that made Milwaukee famous. Not all filters do so.
When you want to fold down the unit put the separate filter container in the sink and go for it.
Another option is to carry gallon jugs of filtered water from home to use for drinking & making coffee. Brushing teeth is another matter!
Dick_B