If your leaking filter is caused by a dirty, damaged or cracked o-ring, cleaning or replacing the o-ring should resolve the issue. Switch off your water supply, press the pressure release button to release trapped air from the unit, and remove the filters from their housing. Check the o-ring for damage and rub it between your fingers to remove dirt. If the o-ring is damaged, replace it with a new one. Lubricate the o-ring with silicone lubricant to prevent it from drying out. Check every o-ring in your system and follow the same instructions for each.