When the raw water containing hardness ions passes through the sodium-type resin in the exchange tank, Ca²+ and Mg²+ in the water will undergo exchange adsorption with Na+ in the resin, removing Ca²+ and Mg²+, eliminating carbonate or non-carbonate hardness, and obtaining softened water. When the amount of Ca²+ and Mg²+ adsorbed by the resin reaches a certain level, the resin needs to be regenerated. The regeneration process involves washing the resin layer with brine from the salt tank. Na+ in the brine will replace the hardness ions on the resin back into the water, and then be discharged out of the tank along with the regeneration solution, enabling the resin to restore its exchange capacity and continue to soften water for production.