In the years we spent in Mexico we used a three stage whole house system (trash filter followed by charcoal filter followed by UV treatment}. It was a 12V unit just in case we lost power in a campsite.
I also installed a 12V water pump in front of that unit to boost water pressure.
We drank the water from that system without a single "Montezuma" moment in the time we spent in Mexico.
We did hit a campsite where they didn't allow reverse osmosis units because of the waste of water, that campsite trucked in water.