What are galvanized pipes?

Galvanized iron pipes are actually steel pipes that are covered with a protective layer of zinc. Galvanized pipes were installed in many homes that were built before the 1960s. Over many years, zinc erodes from galvanized pipes. Corrosion can build-up on the inside walls of the pipes and creates the potential for lead to accumulate over time. Corrosion in galvanized pipes can lead to lower water pressure and water quality issues.

Should I be concerned about my galvanized pipes?

Customers who have galvanized pipes and have or had lead service lines can potentially have lead released in tap water from these corroded pipes. Customers that had lead service lines replaced, but still have galvanized pipes, are still susceptible to lead in water from lead released from the galvanized pipes. Customers that never had lead service lines, but have galvanized pipes, are not at significant risk for lead release from galvanized iron pipes.

How can customers determine if they have galvanized pipes?

Find where your piping enters your home and then scratch it. If the piping is:

  • Copper —the scratched area will have the look of a copper penny.
  • Galvanized steel —the scratched area will be a silver-gray color and have threads.
  • Plastic —usually white in color and you will be able to see a clamp where it is joined to the water supply piping.

A plumber or qualified home inspector can advise you of the type of pipes in your home.

What is the relationship between galvanized pipes and lead?


Image of galvanized pipe with lead build-up

Galvanized piping may accumulate lead deposits over time.

Homes that have galvanized pipes and have or had lead service lines are at risk for the release of lead in water from corroded pipes. In-home galvanized iron pipes are found to accumulate lead that is released from lead service lines. As galvanized pipes corrode and form rust, lead that is accumulated over decades is likely to be found deep in the interior walls of rusty pipes. Lead in galvanized iron home plumbing can periodically contribute to lead in drinking water. The only way to ensure that lead is not mobilized from plumbing to tap in a given home is to fully replace the galvanized plumbing and lead service lines. Galvanized pipes may continue to serve as a lead source in drinking water long after all other sources of lead have been removed, including lead service lines and fixtures.

How can lead be released from galvanized pipes if the lead service lines have been replaced?

Lead accumulated in corroded pipes can persist and be present in household tap water after full replacement of lead service lines, potentially for the remaining service life of the galvanized plumbing. Although lead service lines have been replaced, the rusted areas of galvanized pipes contain deep layers of iron and lead minerals that have accumulated over decades and continue to be released in water. Lead released immediately after lead service line replacement can increase as a result of disturbing the fragile interior surfaces of in-home corroded galvanized pipes. Lead release following lead service replacement varies with location. Typically, a decreasing trend is found in lead release as time elapses following lead service replacement.

What factors should I look for that can increase the release of lead from galvanized pipes?

Lead release from galvanized plumbing can be increased by excessively high water flow or physical disturbances, such as water hammer (vibration of the pipes when they are suddenly turned on or off quickly). Any modifications or improvements to the plumbing, including water heater installations or even fixture replacements, could potentially lead to short term spikes in lead release.
Content retrieved from DC Water & Sewer Authority