Kinetico DO Cap Seal Part Number 8628

The Kinetico DO Cap Seal (Part No. 8628) is a genuine replacement O-ring designed to ensure a watertight seal beneath the Discharge Outlet (DO) cap on many Kinetico water softeners. This precision-made seal prevents internal and external leaks, helping your softener maintain optimum performance and reliability.

Technical specifications

Symptoms that mean you need this part

• Water seeping from around the DO cap
• The softener fails to build pressure or leaks to drain
• You're servicing or rebuilding your Kinetico valve (recommended every 5–10 years)

Why it fails / why it matters

This seal sits beneath the DO cap and takes the pressure of every service and regeneration cycle. As the elastomer hardens with age and chlorine exposure, it loses its ability to seal fully, letting water weep out around the cap or allowing air ingress that affects system pressure.

Why buy this from WrekinWater

WrekinWater has served more than 50,000 customers over 15 years from its base in Bettisfield, Shropshire, and stocks genuine Kinetico seals and internal valve parts alongside Pentair Fleck, Autotrol and Clack components. As a UK-registered company (Company No. 11000488) rated Excellent on Trustpilot, we help you get the exact seal your valve needs.

How to fit it

1. Isolate the softener at the bypass valve and relieve system pressure
2. Remove the DO cap and clean the cap and mating surface thoroughly
3. Apply a thin layer of food-grade silicone grease to the new seal (never petroleum jelly)
4. Seat the O-ring evenly to avoid twisting or pinching
5. Refit the DO cap and restore the water supply, checking for leaks