The answer to 'why is my water softener constantly running' is that your water softener may have a mechanical or electrical issue causing it to continuously cycle. This can be due to a stuck valve, a malfunctioning timer, or a problem with the water pressure or flow rate.
Some common symptoms of a constantly running water softener include high water usage, increased energy bills, and the softener never going into a regeneration cycle. The solution may be as simple as adjusting the settings or troubleshooting the control valve, but it's best to have a professional plumber inspect the system to diagnose and fix the underlying issue.