Some of the water pipes running beneath Philadelphia’s streets were installed in 1824 — two years before the city hosted the nation’s 50th birthday celebration. Two centuries later, many of those pipes are still in service.
Philadelphia’s water system stretches across roughly 3,300 miles of water mains, drawing from the Delaware and Schuylkill Rivers to serve about 1.6 million people. The Philadelphia Water Department replaces approximately 20 miles of those mains each year. But with infrastructure spanning two centuries, the backlog is enormous.
The American Society of Civil Engineers gave Pennsylvania a C- grade on its infrastructure report card — noting that the state has “some of the oldest infrastructure in the country” and faces “substantial maintenance backlogs.”
Lead Service Lines: A New Program for an Old Problem
Philadelphia has never used lead for its main water distribution pipes. But the smaller service lines — the pipes connecting city mains to individual homes — are a different story. The Philadelphia Water Department estimates that roughly 1 in 20 properties may have a lead service line.
For over 25 years, the city has used zinc orthophosphate as a corrosion control treatment. This chemical forms a protective coating on the inside of pipes, reducing the amount of lead that leaches into the water. It’s an effective mitigation strategy, and the city’s lead testing results have generally shown 90th percentile levels below the EPA’s 15 parts-per-billion action level.
But corrosion control is a Band-Aid, not a fix. The lead is still there.
In 2026, Philadelphia is launching its first proactive lead service line replacement program — meaning for the first time, the city will replace lead lines that aren’t being excavated as part of other construction projects. The initial pilot targets neighborhoods in North and West Philadelphia, with approximately 1,000 lead service lines budgeted for replacement in the first phase.
The program is funded through a combination of federal and state grants — including Infrastructure Investment and Jobs Act dollars and PENNVEST funding — plus the water department’s own capital budget. For homeowners, the replacement is offered free of charge when it coincides with scheduled water main construction. The city also offers zero-interest loans through its HELP program for homeowners who want to voluntarily replace their lead service lines ahead of the schedule.
Residents can check their service line material through the Philadelphia Water Department’s interactive map.
The 2023 Chemical Spill
Philadelphia’s most recent high-profile water event wasn’t about aging pipes — it was about the vulnerability of surface water sources.
In 2023, a chemical spill in the Delaware River prompted bottled water advisories across the entire Philadelphia region. While the treated water supply was ultimately deemed safe, the event shook public confidence and highlighted a reality that surface water systems face: your drinking water quality is only as reliable as the health of the river it comes from.
Industrial legacy along both the Schuylkill and Delaware corridors creates ongoing source water quality challenges. Decades of manufacturing, military operations, and chemical processing have left contaminants in the watershed that require constant vigilance and advanced treatment to manage.
Contaminants to Watch
Like all large surface water systems using chlorine disinfection, Philadelphia deals with disinfection byproducts — the compounds that form when chlorine reacts with organic matter in the water. The city manages these within EPA limits, but they’re a persistent treatment challenge.
Philadelphia also conducts comprehensive PFAS testing. The utility tests for HFPO-DA (GenX), PFOS, PFOA, and numerous other PFAS compounds. Most recent results have shown detections below EPA action levels, but PFAS monitoring is ongoing as federal standards continue to tighten.
The EWG Tap Water Database provides detailed contaminant data for the Philadelphia Water Department (PWS ID: PA1510001), showing results across hundreds of tested contaminants from 2021 through 2023.
Green City, Clean Waters
Philadelphia deserves credit for one of the most innovative water infrastructure programs in the country. Launched in 2011, the Green City, Clean Waters program is a $4.5 billion, 25-year initiative that takes a fundamentally different approach to stormwater management.
Instead of building massive underground tunnels and traditional gray infrastructure to handle storm runoff — the approach most cities take — Philadelphia invested in green infrastructure: rain gardens, permeable pavement, tree trenches, and green roofs that absorb and filter stormwater before it overwhelms the sewer system.
It’s a model that other cities are studying and replicating. And it addresses a real problem: combined sewer overflows that mix untreated sewage with stormwater and discharge it into waterways during heavy rain events.
Rising Water Bills
Philadelphia’s water and sewer rates have been increasing steadily, driven by the cost of maintaining and replacing century-old infrastructure. The city’s capital budget for water infrastructure runs in the hundreds of millions annually.
For residents who struggle with water costs, the Philadelphia Water Department offers the Tiered Assistance Program (TAP) — an income-based program that adjusts water bills based on ability to pay. It’s one of the more progressive water affordability programs in the country.
What Philadelphia Residents Should Do
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Check your service line. Use the Philadelphia Water Department’s service line map to find out what your service line is made of. If it’s lead or unknown, plan accordingly.
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Get your water tested. The Philadelphia Water Department and private labs offer lead testing. Testing tells you what’s actually coming out of your tap — not just what’s leaving the treatment plant.
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Learn about the replacement program. If your home has a lead service line, find out where it falls in the city’s replacement timeline. You may also qualify for the HELP loan program if you want to replace it sooner.
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Flush your pipes. Run cold water for at least 30 seconds before using it for drinking or cooking if your home has older plumbing or a lead service line.
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Use a certified filter. Point-of-use filters certified to NSF/ANSI Standard 53 or 58 can reduce lead levels significantly. Reverse osmosis systems are particularly effective.
Philadelphia’s water infrastructure tells the story of American urbanism itself — pipes laid in the era of horse-drawn carriages still carrying water to homes with broadband internet. The city is investing seriously in modernization, but two centuries of infrastructure debt takes more than a few budget cycles to address.
If you’re concerned about your water quality, a certified water treatment professional can test your water and help you find the right solution for your home.