Abstract: A water softener control includes a cell of sampling resin which received periodic samples of water which has passed through a major portion of the softening bed. The sampling resin changes volume when it becomes exhausted and the change in volume is employed to initiate regeneration of the softening bed. At the start of the regeneration cycle, regenerative fluid is delivered directly to the sampling resin as well as to the softening bed. The delivery to the sampling resin is through a control valve which is piloted by pressures at a venturi injector which is used to withdraw regenerative fluid from a brine tank. A vacuum operated control valve which is responsive to the closing of an air check valve in the connection between the injector and the brine tank may be employed to positively close the connection from the sampling cell to the injector when the supply of regenerative fluid is exhausted.