A small percentage of customers might have lead service lines on their property. Customers who are unsure about their service lines should contact a WSSC Water registered plumber to inspect the pipes. In addition, some homes could have lead solder, which was used to connect copper plumbing. In 1986 the EPA banned the use of lead solder in water pipes. In accordance with EPA guidelines, WSSC Water conducts water quality tests every three years on selected homes with a high probability of containing lead-soldered copper plumbing. In addition, additives in the drinking water provide a preventive coating for the pipes (see below).