One of the very first accessories we bought for our motorhome was the water purification systems from 'Nature Pure'.
No need to buy bottled water ever again, as it instantly purifies any drinking water. I first bought one of these systems for a boat which, following its last top up, the water absolutely reeked of chlorine. So much so, you could smell it on your hands after washing. It was as sweet as the proverbial when delivered by the tap supplied with the kit.
It's an American system and, over in France, the cheapest I could find was over 400€ at a chandlers. They are over £300 in the UK but we bought one for just short of £250 from the company in England who import them.
We first saw how efficient the system was at a boat show demonstration where they purified canal water making it fit to drink at the turn of the tap Easy to fit with no electricity supply to worry about. You need never clutter up the place with bottled water again!
Not the cheapest system but possibly and demonstrably the best Germ, chlorine, and chemical remover there is!