How Old Pipes Are Poisoning America's Water

The pipes under America's cities are old. Not "needs maintenance" old — genuinely ancient by infrastructure standards. The American Water Works Association estimates that the US has between 6 and 10 million lead service lines still in operation, most installed between 1900 and 1986 when lead pipes were standard for connecting water mains to buildings.

These aren't a relic of a few backward municipalities. They're in Chicago (an estimated 400,000 lead service lines), Detroit, Milwaukee, Pittsburgh, Newark, and hundreds of smaller cities. They run under lawns and sidewalks, invisible, slowly leaching lead into water at rates that depend on water chemistry, temperature, and how long water sits in contact with the pipe.

The Infrastructure Investment and Jobs Act of 2021 allocated $15 billion specifically for lead service line replacement — the largest federal investment in drinking water infrastructure in decades. It sounds like a lot. When you realise that replacing a single service line costs between $3,000 and $10,000, and there are potentially 10 million of them, the math is immediately humbling.

Lead service line replacement will take decades. In the meantime, tens of millions of Americans are drinking water that passes through lead pipes every day, with exposure levels that depend largely on factors they cannot see, test, or control without making a deliberate effort.

Not all lead pipes are equally dangerous — the amount of lead that leaches into water depends on a specific set of conditions that vary by house, by neighbourhood, and by season.

Age and material Lead service lines installed before 1986 are the primary concern. Inside the home, lead-tin solder on copper pipes (banned in 1986) and older brass fixtures are secondary sources. Even newer "low-lead" brass fixtures certified under current standards can contain up to 0.25% lead by weight — enough to contribute to exposure.

Corrosion chemistry This is the critical variable — and the one Flint got catastrophically wrong. Water that is slightly alkaline and contains certain minerals forms a thin protective scale of calcium carbonate or lead carbonate on the inside of lead pipes, dramatically reducing leaching. Acidic, soft water — low in alkalinity and minerals — is highly corrosive to lead. When Flint switched to the corrosive Flint River water without adding corrosion inhibitors, it stripped that protective scale off millions of lead pipes throughout the city.

Contact time The longer water sits in contact with lead pipes, the more lead it absorbs. The first-draw water in the morning — after sitting overnight — typically has the highest lead concentration. Water that has been flowing recently has lower lead.

Temperature Hot water dissolves lead more rapidly than cold. The instructions to never use hot tap water for cooking or drinking are based on this chemistry, not just on the risk of scalding.

The Flint water crisis is the most extensively documented lead-in-water event in American history, and what it reveals about the regulatory system is as important as what it reveals about infrastructure.

The crisis had a specific technical cause: the switch to Flint River water without implementing corrosion control, violating the Lead and Copper Rule. But the regulatory failure that allowed thousands of children to be exposed for 18 months before federal action was taken was systemic.

What the Lead and Copper Rule failed to prevent • Sampling protocols allowed utilities to pre-flush taps before sampling, removing the first-draw water most likely to show high lead — a practice that systematically produced artificially low results • The 15 ppb action level — the trigger for required remediation — is not a health-based standard; it's an achievability standard. The health-based MCLG is zero. • No federal requirement existed for utilities to disclose lead service line locations to residents

The 2021 revisions The EPA's revised Lead and Copper Rule (LCRR) addresses some of these failures: utilities must now inventory lead service lines, improve sampling protocols, lower the action level trigger over time, and notify residents when lead is detected. It's a meaningful improvement. Whether it's enough, implemented quickly enough, is still being debated.

The justice dimension The communities with the highest density of lead service lines are disproportionately low-income communities of colour. This isn't coincidental — lead service lines were laid in the early 20th century, and the neighbourhoods that have received the least infrastructure investment in the decades since are those that already faced systemic disinvestment.

The Infrastructure Law's $15 billion for lead service line replacement is the most significant federal commitment to solving this problem — but it will take years to translate into action at your street.

What the law requires The EPA's revised Lead and Copper Rule requires water systems to: • Complete a full inventory of lead service lines by 2024 • Replace all lead service lines within 10 years (revised deadline) • Notify residents when lead service lines are found serving their properties • Replace service lines when they work on the utility-side of the connection

What you can do now You don't have to wait for your utility to replace your service line to reduce your exposure.

• Run your tap: Flush cold water for 30 seconds to 2 minutes each morning before drinking or cooking — this clears water that's been in contact with your service line
• Use cold water only: Never cook or make formula with hot tap water, which contains significantly more dissolved lead
• Filter your water: NSF/ANSI Standard 53-certified filters (including certain Brita models, PUR filters, and under-sink systems) remove lead effectively from drinking water
• Test your tap: Independent testing costs $20–50 and tells you your actual exposure — not an average across your water system

How to find out if you have a lead service line Contact your water utility — the new inventory requirements mean most utilities now know the material of the service lines they own. The portion of the line inside your property, however, may be unknown. A licensed plumber can inspect it.