Pentair EPDM O-Ring for Pentek No5 & Slimline Housings

This Pentair O-ring, part number 100687, is the standard EPDM replacement seal for Pentek No5 and slimline filter housings, available from WrekinWater as a single O-ring or a box of twelve for trade use.

Signs this seal needs replacing

• Weeping or dripping from around the housing sump.
• The O-ring feeling hard or brittle rather than soft when removed.
• Repeated leaks after tightening the sump back onto the head.
• Visible cracking or a flattened profile on the old seal.

On Pentek No5 and slimline housings, this O-ring is the only barrier keeping mains-pressure water inside the sump. EPDM resists chlorine and general wear better than many rubbers, but it still perishes with age and with the repeated compression that happens every time the sump is removed for a cartridge change.

WrekinWater stocks genuine Pentair 100687 O-rings in both single and box-of-12 quantities, useful whether you're changing one housing at home or servicing several units, and backs it with 15 years of experience supplying Pentair parts.

How to replace it

1. Shut off the water supply and open a downstream tap to release pressure.
2. Unscrew the sump from the housing head using a housing wrench.
3. Remove the old O-ring from the groove in the head.
4. Wipe the groove clean and lightly grease the new O-ring with food-safe silicone grease.
5. Fit the new O-ring and screw the sump back on hand-tight plus a small turn.
6. Restore the water supply and check for leaks before leaving the housing in use.