University of Delaware study reveals 2,000 century-old lead pipes in Wilmington. What happens next?

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Hidden beneath Wilmington’s streets for nearly a century, lead pipes have quietly carried water through thousands of homes. But thanks to a recent effort led by University of Delaware researchers and students, the city now has a clearer picture of how widespread the old pipes are, and what needs to happen next.

A team of environmental engineering students, working under Gerald Kauffman, director of the University of Delaware Water Resources Center, conducted careful research into historic city records.

“Out of the 70,000 [connections], the bottom line is working with the city’s consultant, the city’s Department of Public Works and the students, they found that 2,000 of the pipes of the 70,000 are lead,” Kauffman said.

The findings mark a crucial step in identifying and replacing hazardous pipes that could pose health risks to residents.

The unfortunate legacy of lead, why these pipes still exist

The use of lead in water pipes dates back to the late 19th century, when it was a preferred material due to its durability and flexibility.

“Going back to the first water pipes that were actually installed in Wilmington in the late 19th century before the turn of the 20th, many of the pipes were lead. That was a material that was easily molded, and little was known about the health effects,” he said.

Congress banned the use of lead pipes in new construction in 1986. But older cities — particularly in the Northeast — still have remnants of these outdated systems. Last year, the Biden administration issued new rules through the EPA that would require old lead pipes to be replaced.

Most modern homes and renovations now use safer materials like copper, while older neighborhoods remain at risk.

Exposure to lead in drinking water has been linked to serious health issues in a child’s development, including neurological damage. Kauffman pointed out examples like the Flint Michigan’s water crisis that underscored the dangers of lead contamination, making identification and replacement of these pipes a high priority.

How UD students helped map Wilmington’s lead problem

The project began when Wilmington’s Department of Public Works approached the University of Delaware Resources Center for assistance. Using decades-old, handwritten public records, students worked to identify where lead pipes were most likely located.

“The idea was to go through the maps that the city has, and we have GIS maps in our office in Newark, and go through all the repair books, the plumbers, the inspectors that the city would send out to work with the homeowners to fix the pipes,” Kauffman said, describing it as a tedious process. “This is physically pouring through these old, handwritten plumbing repair records, and cursive writing and abbreviations … some of these go back to 1926.”

The findings were significant — not just in scale, but in their impact on cost-saving efforts. Instead of the city having to dig up lawns and streets to locate lead pipes manually, the students’ work provided a targeted list of affected homes.

“My estimate is that the students saved the city about $15 million,” he said.

What happens next?

Now that the lead pipes have been mapped, Wilmington can replace them.

“Now the city can contract the plumbers to go systematically and replace these connections from the street to your house,” Kauffman said. “That costs about $3,000 per connection.”

The city is also using chemical treatment to prevent lead from leaching into residents’ drinking water.

“Wilmington adjusts the water’s pH and adds phosphate to neutralize it. The city attends to that religiously, so even if there is a lead pipe, the water going through is neutral, and therefore the lead won’t leach out,” he said.

Wilmington’s Commissioner of Public Works Kelly Williams and Water Division Director Chris Oh outlined the next steps for the city.

“The first step that we’ve taken is notifying all customers about their service line materials — whether they have lead, galvanized, or unknown pipes,” Oh explained. “Right now, we are focused on identifying the remaining 14,000 unknown service lines. We are also asking residents to help us by completing a survey to determine their own service line materials, which is much more cost-effective than digging up roads or sidewalks.”

Williams added that the city is following federal guidelines for lead replacement efforts.

“Under the federal requirements set during the Biden administration, a city of our size is expected to identify and replace most lead lines within 13 years,” she said. “While these regulations could change under a new administration, we are committed to working within that 13-year timeframe. Over the next year and a half, our focus is on identifying the remaining lead and galvanized lines so that we can develop a clear, phased replacement plan.”

Kauffman offered a simple test for homeowners who want to check if their home has lead pipes:

• Locate the pipe leading to your water meter.
• Use a magnet. If the magnet sticks, the pipe is not lead.
• If the magnet does not stick, scratch the pipe with a penny. If it turns copper-colored, it’s safe. If it scratches gray or chalky, it’s lead.
• Call Wilmington’s water department for further assistance.

As more cities reckon with aging infrastructure, efforts like this student-led initiative could provide a cost-effective blueprint for safer drinking water — one old, handwritten record at a time.