I learned that the water supply system shall have a maximum of 8-percent lead content, way back when I was studying for the journeyman plumbing test. Learning this concerned me. I knew that lead was taken out of paint and gas back in the 70's. Why would any lead be allowed in the water supply system? Lead has no role in the healthy functioning of any organism on the planet. It is not a trace mineral. Lead is not essential for body functioning.