O-Rings are used to seal the water filter housing cap to the water filter housing sump to prevent leaks. It is important to lubricate your O-ring with food grade silicone grease.

2 x O-rings for standard 10″ x 4.5 filter housing (big blue whole house filter)

Recommended replace O-ring every 2-3 years

If you do not know the size of your system’s O-ring, open the filter housing and measure the diameter of the O-ring. Your housing determines your O-ring size and not the filter that is used inside your housing.