Why is Lead Used in Water Pipes and Plumbing?
The answer goes back literally thousands of years to the first plumbing systems, which are named after the word “lead” in Latin, plumbum. Lead piping was used because of its unique ability to resist pinhole leaks, while being soft enough to form into shapes that deliver water efficiently. Lead was used in many other common products as well until scientific advancements in the 20th century demonstrated the element’s toxicity. The plumbing industry voluntarily took significant steps to reduce lead exposure.
Why Lead in Water Is Still a Concern Today
There are a number of reasons why trace amounts of lead can be found in the water supply today:
- Nearly all homes built before the 1980s still have lead solder connecting copper pipes.
- Lead still can be found in some interior water pipes and in pipes connecting a home or business to the main water pipe in the street.
- While lead may still be found in metal water taps, these products must pass rigorous NSF/ANSI 61 testing and certification to assure the lead content is below safety thresholds.
- Water chemistry also affects lead levels. Water not treated properly for corrosion control may cause lead to leach from leaded plumbing materials into the water. Lead found in tap water typically comes from corrosion of fixtures or from solder connecting the pipes. Lead also can leach into a water supply when water sits in leaded pipes for many hours. Carefully controlled water chemistry prevents dangerous levels of lead from entering the drinking water system from the pipes.
- Some major U.S. cities still have 100 percent lead piping bringing water from the utilities to homes and businesses. The dissolved oxygen in the water combines with the metal at the surface (copper, zinc or lead) to form a metal oxide. This oxidation layer naturally develops through the decades to coat lead piping and prevent lead from getting into the water supply. When water conditions require it, water utilities also add lime or orthophosphates as a further barrier to prevent lead from getting into drinking water.
Read more about lead pipes and plumbing at SafePlumbing.org