Galvanized Plumbing Key Questions & Answers

You may download the complete FAQ sheet on household plumbing (PDF 950 kb)

Why did DC Water decide to hire a firm to do a study on lead and old household plumbing?
DC Water wanted an independent expert to provide scientific scrutiny of its data and commissioned a study conducted by HDR Engineering Inc. to examine the relationship between lead in drinking water and galvanized plumbing.
The study was presented in October 2009 and a journal publication is being prepared that will go through a peer review process before publication.
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 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.
Does lead released from galvanized pipes vary by location?
The potential for lead release from galvanized plumbing at a given home must be assessed on an individual basis because lead released from galvanized plumbing can differ substantially in magnitude and behavior from one location to another.
Other factors, such as plumbing history, pipe layout in the home, and length of the lead service line might impact the degree to which lead is accumulated in galvanized plumbing at a given location.
Does the current corrosion control treatment effectively minimize lead release from galvanized pipes?
The Washington Aqueduct is responsible for treating the drinking water in the District of Columbia and adds the common food-grade chemical orthophosphate to reduce pipe corrosion.
Introduced in August 2004, orthophosphate has reduced lead concentrations to below EPA's action level of less than or equal to 15 parts per billion.
Orthophosphate works by creating a thin protective coating inside pipes and plumbing fixtures to minimize the corrosion of pipes.
Orthophosphate binds to galvanized pipes, but is only partially able to prevent the rust from breaking off and releasing lead and iron.
Does flushing your water for a specific time decrease the presence of lead from galvanized pipes?
If you have galvanized pipes and have or had lead service lines, lead can be released at any time, and may still be present in water after flushing your taps.
The study recommends replacing galvanized pipes or using NSF certified filters to prevent lead in drinking water.
If you have lead service lines and no galvanized pipes or if you have galvanized pipes and never had a lead service line, DC Water recommends flushing your water for at least two minutes prior to using water for cooking or drinking, when the water has not been used for several hours.
Do galvanized pipes cause discoloration in water?
Yes, in-home galvanized pipes can release iron and cause discoloration.
Based on the study results, is my water safe to drink?
Yes, the drinking water produced by the Washington Aqueduct and delivered to DC residents by DC Water meets all U.S. Environmental Protection Agency (EPA) drinking water standards.
DC Water takes exposure to lead very seriously. Since 2003, DC Water has made exceptional progress in reducing drinking water lead levels. We are far below EPA limits, in fact, our results are lower than the top five major US cities in the northeast, based on current consumer confidence reporting.
If you have or had lead service lines and still have galvanized plumbing, DC Water recommends replacing lead service lines and galvanized pipes or drinking filtered tap water.
What if I am pregnant or have young children?
We take exposure to lead very seriously. If you are pregnant; have children under the age of six; have lead service lines; and/or previously had lead service lines and still have galvanized plumbing:
  1. drink filtered tap water and
  2. use filtered tap water to prepare infant formula or concentrated juices until the source has been identified and removed.
Boiling water does not reduce lead levels.
The District of Columbia Department of Health's Childhood Lead Poisoning Prevention Program (DC DOH) provides information on how to get a simple blood lead test to check lead levels in young children, pregnant women, and nursing mothers. You can also learn more about how to protect you and your family from lead by contacting the DC DOH at (202) 442-9216, or by visiting its website If you have additional concerns about a child's health, or would like the screening done by his/her own doctor, please contact his/her pediatrician.
Is it useful to have my water tested for lead?
If you have or had lead service lines and have galvanized pipes, it is likely lead is only periodically released in the water and a single lead test may not be an effective tool in identifying actual lead levels. However, if you have a concern, see our list of certified testing laboratories.
If you are interested in additional information, contact our Customer Service department at (202) 354-3600.
What types of filters does DC Water recommend for removing lead in water?
If you are purchasing a treatment device to reduce lead levels at your tap, choose a treatment device installed at the tap or use a filtration pitcher. These devices must be used, installed, operated and maintained according to manufacturer instructions.
Be sure to purchase a treatment device certified by an independent testing organization, such as NSF International. You can search the NSF International website for certified drinking water treatment devices by visiting.
Please be advised that neither the EPA nor DC Water certifies or endorses specific home drinking water treatment devices.
What do I do if I own a home that has galvanized pipes?
According to the study, the only way to fully ensure that lead is not mobilized from galvanized plumbing in a given home is to fully replace the galvanized plumbing.
What do I do if I live in a rental property that has galvanized pipes?
Contact your property manager or landlord to discuss this issue.
See the recommendations above for filter options.
How long has DC Water known about the finding of the HDR Report?
The study was presented in October 2009.
How is DC Water planning to alert stakeholders and residents of these new findings?
DC Water will be hosting a forum and will provide information and recommendations to all its customers on the website, in the customer newsletter and in a future bill.
Will the Department of Health and EPA be notified?
DC Water has shared the study results with DDOH, DDOE and EPA.
Where can I go for additional information or assistance?
DC Water and Sewer Authority —For questions relative to water quality in your home, contact the Drinking Water Division at (202)612-3440, email
DC Department of the Environment —You can learn more about how to protect you and your family from lead by contacting the DDOE at (202) 535-2600, or by visiting the website
Environmental Protection Agency —For information on reducing lead exposure around your home and the health effects of lead, visit EPA's website at

What We Do