Zeolite for Water Treatment

I have used natural zeolite of the phillipsite family of Na homoiconic form as a model to treat water from dissolved heavy metals like iron and cadmium. The particle size was 0.6-1.4 mm. It has been found that the efficiency of the treatment is affected by hardness. I want to know if any body or a water facility is using any type of zeolite to treat water at the municipal level and how they manage the interfering ions.