AWWA JAW56619

The use of metallic water piping as part of a building's electrical grounding system has been a commonplace practice for more than 80 years. When electrical transformers serve multiple buildings, the water services and distribution piping can act as parallel neutral return paths for stray current from building electrical systems to the transformers. Electrical resistance in pipe connections, if present, forces some fraction of the stray current to flow through the parallel water path. Discharge of current on the inside of the pipe increases metal release. Previous studies on the effects of grounding on water quality and metal release did not investigate the effects of resistance or dielectric fitting. This study investigated the effects of dielectric fittings on water quality. Copper tubing that had been modified with inserted dielectric fittings was filled with potable water from two different water sources and was tested with applied alternating current (AC) voltages of up to 123 V for periods of up to 110 h. Significant increases in copper, lead, and zinc in stagnant potable water were measured in less than 24 h at applied voltages of ~50 VAC. Metal release generally increased with charge transfer, in accordance with Faraday's law. Includes 13 references, tables, figures.