For the most part, reverse osmosis systems are no longer used by any of the leading brands of water filters. Current research indicates that this outdated process actually disrupts the healthful nature of water. RO supposedly purifies water by removing the natural minerals and metals. Years ago, it was believed that these substances were unhealthy, but since then it has become scientifically evident that minerals and metals that occur naturally in water are actually what make it healthy and give it good taste.