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.
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Lead in Water Pipes: How Old Plumbing Affects Your Water
Understanding how lead enters drinking water, what regulations are in place, and how to assess your own home.
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How Lead Gets Into Drinking Water
Lead does not typically exist in source water. Instead, it enters drinking water through corrosion, where water interacts with lead-containing materials in the plumbing system. The three primary sources are lead service lines (connecting the water main to your home), lead solder (used to join copper pipes before 1986), and brass fixtures and fittings(which contained up to 8 percent lead until 2014).
The EPA estimates that between 6 and 10 million lead service lines remain in use across the United States. Homes built before 1986 are at the greatest risk due to lead solder in copper pipe joints, which contained up to 50 percent lead.
15 ppb
Original EPA Action Level
10 ppb
New LCRI Trigger Level
Pre-1986
Lead Solder Risk Period
0.25%
Current "Lead-Free" Brass Limit
Factors That Increase Lead Leaching
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.
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.
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. Never use hot tap water for consumption purposes in homes with older plumbing.
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.
Lead and Copper Rule Update
The EPA's original Lead and Copper Rule (LCR), published in 1991, required water systems to take action if lead exceeded 15 ppb in more than 10 percent of sampled homes.
In October 2024, the EPA finalized the Lead and Copper Rule Improvements (LCRI), which significantly strengthens the original regulation. The LCRI lowers the action level to 10 ppb, requires all water systems to complete a mandatory service line material inventory, 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.
Practical Steps to Reduce Exposure
1
Flush Your Tap
Run 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.
2
Use Cold Water for Cooking
Always use cold water for cooking, drinking, and preparing infant formula. Hot water dissolves lead more readily than cold water and should never be used for consumption.
3
Clean Aerators Regularly
Lead particles and sediment can accumulate in the fine mesh screens of faucet aerators and re-enter the water stream. Remove and clean aerators every few months.
4
Install NSF/ANSI 53 Filters
Consider a point-of-use water filter certified to NSF/ANSI Standard 53 for lead reduction. These are available as pitcher filters, faucet-mounted filters, and under-sink systems.
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.
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