The home water treatment systems that consume water in the treatment process are reverse osmosis systems and water softeners. Point-of-use water filters that attach to the kitchen sink faucet do not consume any water. If water efficiency is a high priority, you can’t do better than a point-of-use filter.
Water softeners and reverse osmosis systems vary tremendously in their use of water for the treatment process. Both systems use water for flushing and regeneration. The amount of water used depends upon the system, the quality of the water being treated, and the amount of water used in the home. Be sure to request water consumption information from the dealer before purchasing any water treatment system or water softener.