Lead can enter drinking water through corrosion of plumbing materials, especially where the water has high acidity or low mineral content that corrodes pipes and fixtures. Homes built before 1986 are more likely to have lead pipes, fixtures, and solder. However, new homes are also at risk: even legally “lead-free” plumbing may contain up to eight percent lead.
Beginning January 2014, changes to the Safe Drinking Water Act further reduced the maximum allowable lead content of pipes, pipe fittings, plumbing fittings, and fixtures to 0.25 percent. The most common problem is with brass or chrome-plated brass faucets and fixtures with lead solder, from which significant amounts of lead can enter into the water, especially hot water.
Corrosion is dissolving or wearing away of metal caused by a chemical reaction between water and your plumbing. A number of factors are involved in the extent to which lead enters the water including the chemistry of the water (acidity and alkalinity), the amount of lead it comes into contact with, how long the water stays in the plumbing materials, and the presence of protective scales or coatings inside the plumbing materials.
To address corrosion of lead and copper into drinking water, EPA issued the Lead and Copper Rule (LCR) under the authority of the Safe Drinking Water Act. The LCR requires corrosion control treatment to prevent lead and copper from contaminating drinking water. Corrosion control treatment means systems must make drinking water less corrosive to the materials it comes into contact with on its way to consumers’ taps.