I see that Alde have now introduced a water treatment unit that uses UV light to sterilise the water and a carbon filter to remove strange tastes. It costs around £260-£300 to buy, and the filter requires changing annually. It seems to me to be the answer to a question that hasn’t been asked. But I guess it will be bought by those who see risk everywhere. We always removed carbon filters from the caravans, and over all our years outdoors never had a problem with water quality from site supplies in UK or Europe. If the taste was too chlorinated then a bottle of water would sort that out. But again rarely did we buy bottled water.