Lead in Water Pipes: How Old Plumbing Affects Your Water

Lead is one of the most well-studied contaminants in drinking water, and its presence in residential plumbing remains a concern for millions of American households. Unlike most water quality issues, lead contamination does not originate at the water treatment plant -- it typically enters water through the pipes, fittings, and solder within the distribution system and inside your home. Understanding where lead comes from and how to identify potential risk factors in your own plumbing is an important step toward informed decision-making.

How Lead Gets Into Drinking Water

Lead does not typically exist in source water -- rivers, reservoirs, and aquifers are generally free of lead contamination. Instead, lead enters drinking water through a process called corrosion, where water interacts with lead-containing materials in the plumbing system and dissolves small amounts of lead into the water flowing through it.

There are three primary sources of lead in residential plumbing:

• Lead service lines -- These are the pipes that connect the water main beneath the street to your home. In many cities, homes built before the 1950s were connected using lead service lines because lead was considered a durable, malleable, and corrosion-resistant pipe material. The EPA estimates that between 6 and 10 million lead service lines remain in use across the United States.
• Lead solder -- Prior to 1986, lead-based solder was commonly used to join copper pipes in residential plumbing. This solder contained up to 50 percent lead. Even though lead solder was banned for use in drinking water systems by the Safe Drinking Water Act amendments of 1986, millions of homes built before that date still have lead solder in their pipe joints.
• Brass fixtures and fittings -- Many older faucets, valves, and connectors were manufactured from brass alloys containing lead. Until 2014, the legal definition of "lead-free" for plumbing components allowed up to 8 percent lead content. The Reduction of Lead in Drinking Water Act, which took effect in 2014, lowered this threshold to 0.25 percent for wetted surfaces.

Factors That Increase Lead Leaching

Not all homes with lead-containing plumbing will have elevated lead levels in their water. Several factors influence how much lead dissolves into the water:

• Water chemistry -- Water that is more acidic (lower pH) or that has low mineral content is more corrosive and more likely to dissolve lead from pipe surfaces. Soft, acidic water is generally more aggressive toward lead-containing materials than hard, alkaline water, which tends to form a protective mineral scale on pipe interiors.
• Stagnation time -- The longer water sits in contact with lead-containing materials, the more lead can dissolve into it. This is why first-draw water -- the first water out of the tap after several hours of non-use -- typically has the highest lead concentrations. Water that has been flowing continuously has less contact time with pipe surfaces.
• Temperature -- Hot water dissolves lead more readily than cold water. This is why health guidance consistently recommends using only cold water for cooking and drinking, particularly for preparing infant formula or baby food.
• Physical disturbances -- Construction activity, water main breaks, and changes to water treatment chemistry can disturb the protective mineral layer that forms on the inside of lead pipes over time. When this layer is disrupted, it can release accumulated lead particles into the water in addition to increasing the rate of dissolved lead leaching.

The Lead and Copper Rule

The EPA's Lead and Copper Rule (LCR), originally published in 1991, is the primary federal regulation governing lead in drinking water. Unlike most drinking water standards, the LCR does not set a Maximum Contaminant Level for lead at the treatment plant. Instead, it requires water systems to monitor lead levels at consumer taps and take action if lead concentrations exceed the action level of 15 parts per billion (ppb) in more than 10 percent of sampled homes.

When a water system exceeds the action level, it must implement corrosion control treatment, conduct public education, and may be required to replace lead service lines. Corrosion control typically involves adjusting the pH and alkalinity of treated water to make it less corrosive, or adding phosphate-based compounds that form a protective coating on pipe interiors.

In October 2024, the EPA finalized the Lead and Copper Rule Improvements (LCRI), which significantly strengthens the original regulation. The LCRI requires all water systems to inventory their service line materials, lowers the action level to 10 ppb, and mandates the replacement of all lead service lines within 10 years. These changes represent the most significant update to federal lead regulation in over three decades.

How to Check Your Home

Determining whether your home has lead plumbing involves a combination of research and physical inspection:

• Check the age of your home -- If your home was built before 1986, it may have lead solder in the copper pipe joints. If it was built before 1950, there is a greater chance that the service line connecting your home to the water main is made of lead.
• Look at your service line -- In many homes, the service line enters through the basement or crawl space wall. Lead pipes are typically dull gray in color and soft enough to scratch with a coin or key, revealing a shiny silver surface underneath. Copper pipes are reddish-brown or green. Galvanized steel pipes are gray but harder than lead and will not scratch easily.
• Contact your water utility -- Many utilities maintain records of service line materials in their system. Under the LCRI, utilities are now required to complete a comprehensive inventory of all service lines, so this information is becoming more accessible.
• Test your water -- The only way to know with certainty whether lead is present in your drinking water is to have it tested. A first-draw sample collected after water has sat in your pipes for at least six hours provides the most informative result. Certified labs can measure lead concentrations down to single-digit parts per billion.

Practical Steps to Reduce Exposure

While the long-term solution for lead in drinking water is the removal and replacement of lead-containing plumbing materials, there are immediate practical steps that households can take:

• Flush your tap by running cold water for 30 seconds to two minutes before using it for drinking or cooking, especially after periods of non-use. This clears stagnant water that has been in contact with your pipes.
• Always use cold water for cooking, drinking, and preparing infant formula. Hot water is more likely to contain dissolved lead.
• Clean your faucet aerators regularly. Lead particles and sediment can accumulate in the fine mesh screens and re-enter the water stream.
• Consider a point-of-use water filter certified to reduce lead. Look for filters that are NSF/ANSI Standard 53 certified for lead reduction. These are available as pitcher filters, faucet-mounted filters, and under-sink systems.

Lead in drinking water is a solvable problem. The combination of updated federal regulations, utility-level infrastructure improvements, and informed household-level action creates a path toward reducing exposure for every community. Knowing what your home is working with is the essential first step.

Disclaimer: The Water Awareness Foundation is an independent educational organization. We are not affiliated with any government agency, water utility, or regulatory body. The information in this article is for educational purposes only and should not be interpreted as medical or legal advice.