Oh you are with Warwick water department then. Always forget about them. That's strange, might be picking stuff up in the pipes, because when I worked there we were told the water was very soft. Usually that question came up when people were installing dishwashers with integrated water softeners, with pw you dont have to use it. And in fact should use a lot less detergent so the machine works better, like half of a normal dishwasher tab.