Assuming you are not limited by financial issues, the above systems are good, better, and best.
At the bare minimum, get the disposable blue inline filter and attach it to the pedestal or faucet before your city water hose connection. Most city or campground water is good to drink straight up. However, some have issues from sand to coli form bacteria.
Once it gets into your system, it is hard to get it out, or even know if it is out.
Sanitize at least once per year using chlorine bleach according to widely available instructions.
I wish you good luck and happy trails.