Lead can enter drinking water when service pipes that contain lead corrode, especially where the water has high acidity or low mineral content that corrodes pipes and fixtures. 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.
Homes built before 1986 are more likely to have lead pipes, fixtures and solder. The Safe Drinking Water Act (SDWA) has reduced the maximum allowable lead content -- that is, content that is considered "lead-free" -- to be a weighted average of 0.25 percent calculated across the wetted surfaces of pipes, pipe fittings, plumbing fittings, and fixtures and 0.2 percent for solder and flux.
Corrosion is a 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) and the types and amounts of minerals in the water,
the amount of lead it comes into contact with,
the temperature of the water,
the amount of wear in the pipes,
how long the water stays in pipes, and
- the presence of protective scales or coatings inside the plumbing materials.
Lead and Copper Sampling Sites include:
1. Single-family structures that:
a. Contain Copper pipes with lead. solder installed after 1982 (or from 1983 to 1988) or contain lead pipes; and/or
b. Are served by a lead service line (collect 50% of samples from LSLs).
2. Multiple-family structures that:
a. Contain copper pipes with lead solder installed after 1982 (or from 1983 to 1988) or contain lead pipes; and/or
b. Are served by a lead service line.
3. Single-family structures that contain copper pipes with lead solder installed before 1983 (or from 1982 and later).