Abstract: A water softening system of the cation exchange type includes a regeneration system where there is a discharge duct for discharging waste flush water to waste from the treatment tank during regeneration with a valve for controlling the outlet and the discharge duct so that during regeneration the water from the treatment tank does not flow to the outlet and is instead directed to the discharge duct. A brine tank is provided for containing a solution of salt in water for injection by a transfer arrangement into the treatment tank with a return valve in the discharge duct operable to return a portion of the waste flush water to the brine tank which is equal to the quantity drawn by a brine transfer arrangement, while all waste flush water not returned to the brine tank is discharged to waste.