Water softeners are designed to "soften" the water by removing "hard" minerals. They work well and are widely used. We have our own line of compact, durable & portable water softeners designed specifically for RV use. Our 16000 Grain Softeners (2000 gallons per charge) are in a tank that is 10.375" x 19.5" (22.5" with cap) and the 8000 Grain Softeners (1000 gallons per charge) are in a tank that is 7" x 19.5" (22.5" with cap).