E08 error and water remains hard even after regeneration

Safety: Wear gloves and eye protection when handling resin or brine. Disconnect power before opening the valve head.

• Verify programming: Check that the raw water hardness and resin capacity are correctly set in the Cillit controller. Incorrect settings can cause premature exhaustion.
• Check salt and brine: Ensure the brine tank contains adequate salt and that the brine level drops during regeneration. If not, resolve any brine system issues (injector, float, brine line).
• Perform a double regeneration: Manually start two consecutive regenerations to fully recharge the resin, especially after a long period without salt.
• Test hardness: Use a Cillit hardness test kit to measure hardness before and after the softener. If hardness remains high despite correct regeneration, the resin may be permanently fouled (iron, manganese, organics).
• Replace resin: If resin is more than 10–15 years old or heavily fouled, plan to replace the Cillit cation exchange resin. This involves depressurizing the system, removing the control head, vacuuming out old resin, inspecting the riser tube and distributors, and refilling with the specified resin volume.