Softener emits a rotten egg or foul odour from softened water

Safety first: Do not drink water with a strong foul odour. Use an approved disinfectant only as directed.

• Sanitise resin bed: Follow Monarch's sanitisation procedure, typically involving adding a measured amount of approved disinfectant (such as sodium hypochlorite at low concentration) to the brine well and running a regeneration.
• Clean brine tank: Empty the brine tank of salt and sludge, wash with warm soapy water, rinse thoroughly, and refill with fresh salt.
• Increase usage or bypass: If the property is unoccupied for long periods, consider bypassing the softener or scheduling periodic regenerations to keep water fresh.
• Check for external causes: If odour is present on both hard and soft supplies, the issue may be with the mains water or hot water cylinder.