The answer to the cost of water softener repair is that it can vary significantly depending on several factors. Generally, minor repairs like replacing a control valve or resin tank can cost between $100 to $300, while more extensive repairs like replacing the entire system can range from $500 to $2,000 or more.
The specific cost will depend on the type and age of your water softener, the extent of the repair needed, the cost of replacement parts, and the labor rates in your local area. It's best to get quotes from multiple local plumbers or water treatment specialists to compare costs and find the most affordable solution for your home.