E18 error and unit indicates drain line restriction

Safety first: Place the unit in bypass and unplug it before working on the drain line.

• Inspect drain hose: Follow the entire length of the Watersoft drain line. Straighten any kinks and ensure there are no low spots where water can collect and freeze.
• Clean flow control: Remove the drain line flow control fitting at the valve. Soak in vinegar to dissolve scale and flush with water.
• Check drain termination: Ensure the standpipe or floor drain is not blocked. Clear any obstructions and maintain an air gap to prevent backflow.
• Verify installation limits: Confirm the drain line length and elevation comply with Watersoft specifications. Shorten or reroute if necessary.

After clearing restrictions, take the unit out of bypass and run a manual regeneration to verify strong drain flow without triggering E18.