O-ring used with the Brine Valve Piston Assembly.
There are Two used in the Valve Assembly.
One on the Brine Valve and One in the Hole that the Brine Valve sits inside.


One o-ring comes on the Brine Valve Piston Assembly ( 60032 ), and the other would be sitting loose in the bottom of the hole where the Brine Valve is installed.

If the bottom oring is missing or damaged, it will result in water slowly filling the brine tank.
see:

• Water Flowing into the brine tank