Despite the fact that our cooling towers are galvanized steel, sitting on steel I-beams attached to 8" steel pipe, which in turn is connected to a lighting arrestor system, we seem to have a problem with some type of electrical/radio noise that is being transmitted through the water to some test equipment. (See VFD FRI/EMI in this forum)We are trying numerous filters on the VFD drive outputs and inputs and so far are having no luck in filtering out whatever it is. The electrical system grounds from the motors back through all panels to the SE and main building ground have all been tested at under 0.02 ohms. Is there any way of trying to trap the interface/voltage/current in the water and take it to ground? Would this cause an unsafe parallel ground situation?