The answer to 'why is my water softener overflowing' is that there are several common causes, including a clogged drain line, a problem with the brine tank, or an issue with the control valve. Symptoms may include water spilling out of the softener, low water pressure, or the softener running constantly.
To troubleshoot, first check the drain line for any clogs or obstructions. Make sure the line is properly sloped and draining freely. Next, check the brine tank to ensure it's not overfilling or leaking. Finally, inspect the control valve for any issues. If you can't identify and fix the problem, it's best to call a professional plumber who can properly diagnose and repair the water softener.