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Water Filter Housing Compatibility
Captain O-Ring's replacement OK7 o-rings are compatible with the following filter housings:
- OmniFilter BF6
- OmniFilter BF7
- OmniFilter BF7a (BF7 Series A)
- OmniFilter BF35, BF36, & BF36C
- OmniFilter BF55 & BF56
- OmniFilter PB35 & PB55
Frequently Asked Water Filter O-Ring Questions
How often do I need to change my filter housing's o-ring?
Captain O-Ring's high quality replacement water filter housing o-rings are designed for reliable extended use. Still, it is typically recommended to replace your o-ring on every third filter change to ensure it is in top shape to prevent leaks.
Can I use grease or lubricant on these o-rings?
Since Captain O-Ring supplies high quality o-rings without surface imperfections or tacky/sticky surface texture, lubrication is typically not needed if the filter housing sealing surfaces are clean and free of debris. Simply wet the o-rings with water before installing. However, if lubrication is preferred, these Buna Nitrile rubber o-rings are compatible with silicone based and petroleum based lubricants, as well as natural lubricants like vegetable oil.
What if I don't know what o-ring part number my filter housing needs?
Not sure which o-ring part number you need for your filter housing? Use our handy printable water filter housing o-ring size chart. Simply print out the chart and lay your old o-ring on the page to see which o-ring it matches with. You can find the size chart listed as "User Guide [PDF]" under the "Product guides and documents" section or the "downloads" section on this page, depending on your Amazon page layout.
Dawn Snyder
Reviewed in the United States on March 8, 2025
Exactly what I needed to fix my leak. Fit perfectly. Exactly as described
MJM
Reviewed in the United States on March 20, 2024
I measured the O ring from a new BF7 unit and the original ring with the unit was bigger than the small ring in the package and the 2nd size in the package was larger than the original ring. I suspect that the oversize ring would work if you ran into a leakage issue. I am keeping these just in case I have a problem in the future. Reasonable price and if functional. Seems like the best choice as none of the seller show the size of the O rings being sold.
Ormonde Butler
Reviewed in the United States on March 23, 2023
Wrong size o-ring needed to be 5 and 5/8 was 5 and 3/4
Sloppyjoejo
Reviewed in the United States on December 4, 2022
I have an older BF7 whole house filter and when I replaced the O-Ring with a standard replacement I could not get it to stop leaking. I put the old O-Ring back on and ordered the Captain O-Ring-OK7 replacement set that included the oversize O-Ring along with the OEM size. It worked great. Don't know how they found out this was a common problem with this unit and started including the extra size option but I am glad they did.
Bradley W.
Reviewed in the United States on December 12, 2022
The device work as I expected it to
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