Lead in Water

How Lead Enters Plumbing Systems?

Lead can enter drinking water primarily through the corrosion of plumbing materials that contain lead. As water passes through old service lines, household pipes, or fixtures made with lead or lead-based solder, the metal can gradually dissolve or break away into the water. This risk is especially relevant in homes built before 1986, when lead-containing plumbing materials were still widely used.

Corrosion occurs when water chemistry interacts with metal surfaces. Factors such as pH, temperature, mineral content, and disinfectants can influence how quickly pipes corrode. Soft or acidic water, for example, can dissolve certain metals more readily, allowing lead to leach into the water. Even relatively small changes to a community’s water source or treatment process can significantly affect corrosion rates, an important lesson from the Flint, Michigan crisis.

Lead contamination does not usually originate at the treatment plant itself. Instead, it can develop along the final part of the distribution system, including private service lines and household plumbing between the water main and the faucet. As a result, contamination can be localized and vary from one property to another, even among neighboring homes. Lead in household water testing in NYC can help residents investigate whether their own tap water may be affected.

Because lead is colorless, tasteless, and odorless, its presence cannot be reliably detected through sight, smell, or taste. Proper testing is essential to identify potential contamination. Addressing the source may require replacing lead-containing plumbing materials, often through coordination among homeowners, municipalities, and public water utilities.

The Difference Between Lead Solder and Service Lines

Both lead solder and lead service lines are major sources of contamination, but they differ in where they’re located and how much risk they pose. Lead solder is a metallic compound once used to join sections of copper pipe. Common in homes built before 1986, it’s typically found inside the walls, near joints, and around water heaters. Over time, as water sits stagnant, lead from solder can dissolve and enter the household supply often in small but harmful quantities.

Lead service lines, by contrast, are full-length pipes that connect a home’s internal plumbing to the municipal water main under the street. Because they are made entirely of lead, these pipes can contribute far more contamination than solder joints. Many cities still rely on tens of thousands of such lines, some installed more than a century ago.

Replacing lead solder is relatively simple homeowners can re-pipe sections or update fixtures with modern, lead-free materials. However, replacing service lines is a much larger challenge. It often requires excavation, coordination with the water utility, and thousands of dollars per connection.

Partial replacements, where only part of the lead line is replaced, can actually make contamination worse by disturbing the remaining lead and releasing particles into the water. For that reason, full-service line removal is now considered the only safe and permanent fix.

Lead Exposure Pathways in Schools and Homes

Schools and homes share a vulnerability to lead exposure, although the risks can differ. In schools, problems often stem from aging plumbing and periods of prolonged water stagnation. When water sits unused overnight, over weekends, or during extended breaks, it has more time to interact with lead pipes, solder, and fixtures. Drinking fountains and kitchen taps can be particularly vulnerable when they are connected through long branch lines.

Testing in schools across the United States has found elevated lead levels even in some relatively new buildings, where components labeled “lead-free” may still contain trace amounts of lead. Because children are especially vulnerable to lead’s harmful effects, regular testing and the replacement of contaminated fixtures are important preventive measures. School drinking water testing in NYC can help schools identify potential concerns and determine where follow-up action may be needed.

In homes, exposure risk depends on the age and condition of the plumbing, water chemistry, and household water-use patterns. Older neighborhoods with original service lines may face greater risks. Lead can leach into water that remains stagnant, including in infrequently used taps in guest bathrooms or basements.

Possible risk-reduction measures include flushing taps appropriately, using certified point-of-use filters designed to reduce lead, and replacing lead-containing pipes where feasible. Families with infants or pregnant women should take particular care because lead exposure can harm fetal development and a child’s developing brain.

LeadWaterWatch encourages homeowners and school administrators to take a proactive approach by testing water, tracking results, and sharing relevant information. These steps can help communities identify potential problems and protect students and households from an invisible hazard with lasting consequences.