Autotrol Tank O-Ring Seal, Autotrol 255, 263,268.278 1010154

The Autotrol 1010154 is the genuine tank O-ring seal (sold by Pentair as "O-ring, Top of Tank 43F") that seals the control valve head onto the resin tank on Autotrol 255, 263, 268 and 278 water softeners — and, thanks to a shared tank-neck design, on Fleck 5600, 9000 and 9100 valves too. If you're searching for an Autotrol water softener seal, a Fleck tank O-ring, or a valve head gasket replacement, this is the part. WrekinWater stocks it as standard, ready to dispatch from our Shropshire warehouse.

Technical specifications

Symptoms that mean you need this part

• A damp patch or slow drip appearing where the valve head sits on top of the tank
• A musty or salty smell building up inside the cabinet
• Visible flattening, cracking or a permanent 'kink' in the old O-ring once the head is lifted off

Why it fails / why it matters

This seal is under constant compression and exposure to treated water for years at a time. Rubber takes a permanent 'set' under that kind of sustained pressure — once it loses its round cross-section it can no longer flex enough to hold a seal, and it starts to weep rather than fail outright, which is why it's often mistaken for 'just a bit of condensation' until the leak gets worse.

Why buy this from WrekinWater

WrekinWater has been supplying genuine Autotrol, Fleck and Clack water softener parts for over 15 years and served more than 50,000 customers — so when you buy this O-ring from us, you're getting a part we've confirmed fits before it ships, not a generic size guess. We're rated Excellent on Trustpilot and dispatch from our own UK stock.

How to fit it

1. Turn the bypass valve to bypass and shut off the incoming water supply.
2. Put the valve through a manual regeneration step (or hold the appropriate button per your manual) to relieve residual pressure in the tank.
3. Release the locking clamp or collar holding the valve head to the tank and lift it straight up and off the riser tube — don't twist, as this can crack the riser.
4. Wipe the tank neck and the seating groove clean, then roll the new O-ring into place without stretching or twisting it.
5. A light smear of food-safe silicone grease helps it seat evenly and protects it on the next service.
6. Lower the head back down square onto the riser tube, refit the clamp, then restore the water supply slowly and check the joint for weeping through a full regeneration cycle.