A method for operating a water softening system (1) comprising an automatically adjustable blending means for mixing a blended water flow V(t)blended from a first, softened partial flow V(t)part1soft and a second untreated water partial flow V(t)part2raw and comprising an electronic control means (11), wherein the control means (11) readjusts the adjustment position of the blending means by means of one or more experimentally determined instantaneous measured values in such a fashion that the water hardness in the blended water flow V(t)blended is adjusted to a predetermined desired value (SW), is characterized in that the control means (11) ignores at least one of the one or more instantaneous measured values for readjustment of the adjustment position of the blending means in one or more defined operating situations, and instead uses the respectively last corresponding measured value that was valid prior to occurrence of the defined operating situation, or a standard value for the corresponding measured value, which is stored in the electronic control means (11). The inventive method reduces the wear of the automatically adjustable blending means and improves the reliability of the adjustment of the water hardness of the blended water.