The testing kit results provide the most conclusive evidence yet of widespread hazards that have remained hidden for decades. Yet as Mayor Rahm Emanuel borrows hundreds of millions of dollars to overhaul the city’s public water system, Chicago is keeping lead service lines in the ground.

Alarming amounts of the toxic metal turned up in water samples collected throughout the city, the newspaper’s analysis found, largely because Chicago required the use of lead service lines between street mains and homes until Congress banned the practice in 1986.

A Tribune analysis of the results shows lead was found in water drawn from nearly 70 percent of the 2,797 homes tested during the past two years. Tap water in 3 of every 10 homes sampled had lead concentrations above 5 parts per billion, the maximum allowed in bottled water by the U.S. Food and Drug Administration .

Amid renewed national attention to the dangers of lead poisoning , hundreds of Chicagoans have taken the city up on its offer of free testing kits to determine if they are drinking tap water contaminated with the brain-damaging metal.

Note: The dots on the map do not represent exact addresses, as the city provides only the block number for each testing location. A small number of water main projects are not mapped because the information included only a single point, not a stretch of street.

One of the homes with the highest levels found so far is Jenny Abrahamian’s bungalow on the city’s Northwest Side.

Block-level results are posted on a city-sponsored website that hadn’t been updated in more than six months before the Tribune began asking questions about the testing kits.

Prompted by concerns raised by the water crisis in Flint, Mich., and an EPA study of Chicago homes published in 2013, the city water department began distributing lead-testing kits to residents on request. The kits included three sample bottles: one for water drawn after household taps have not been used for at least six hours, another for a sample collected after three minutes and the third after five minutes.

Even after water had been running for five minutes, 9 percent of the homes tested had lead levels above the FDA’s bottled water standard.

City and EPA officials advise that residents can protect themselves by flushing household plumbing for three to five minutes when water hasn’t been used for several hours. But in one of five Chicago homes tested since January 2016, the Tribune analysis found, samples contained high levels of lead after water had been running for three minutes.

“Since Mayor Rahm Emanuel took office, he has made it a priority to improve Chicago’s overall water quality and infrastructure,” the statement reads. “Today, the city’s water exceeds the standards set by the ( U.S. Environmental Protection Agency ) for clean, safe drinking water. And the Department of Water Management continues to take a proactive approach to mitigating lead in our water system and is continually evaluating additional methods of lead mitigation.”

Adam Collins, Emanuel’s chief spokesman, referred questions to the Department of Water Management, where a spokeswoman earlier had said she would need to consult with the mayor’s office before responding to the Tribune’s analysis. Asked why the city hasn’t removed lead service lines it once required by law, the department emailed a three-sentence statement:

“Chicago could be a leader on nationwide solutions to this problem, but instead they appear to be sticking their heads in the sand,” said Tom Neltner, chemicals policy director at the nonprofit Environmental Defense Fund and former assistant commissioner of the Indiana Department of Environmental Management.

As a result, critics say, the city is leaving scores of Chicagoans at risk and failing to seize an opportunity to fix more than one problem when crews dig up streets to replace aging water mains.

Under the city’s plumbing code — the same ordinance that for nearly a century mandated the use of lead pipes to convey water to single-family homes and small apartment buildings — individual property owners are responsible for maintaining service lines. The mayor’s office has said it is up to homeowners, not the city, to decide if it is worth replacing the lead pipes at their own expense.

Abrahamian was so alarmed by the results — the first sample she collected contained 250 ppb of lead — she invested in a $1,100 system that filters every drop of water coming into her home, as well as an additional reverse-osmosis filter at her kitchen sink for drinking water.

“I’m really happy I did,” she said. “But this definitely isn’t something that everyone could afford.”

Water from Lake Michigan generally is lead-free after leaving the city’s treatment plants; it becomes contaminated only after passing through service lines and internal plumbing made of lead. Levels of the toxic metal in tap water can vary widely between homes and during different times of day, depending on water usage, the length of the service line and other factors that can limit the effectiveness of corrosion-inhibiting chemicals added to the water supply.

Lead is unsafe to consume at any level, according to the EPA and the U.S. Centers for Disease Control and Prevention. Ingesting tiny concentrations can permanently damage the developing brains of children and contribute to heart disease, kidney failure and other health problems later in life. A peer-reviewed study published last month in The Lancet, a London-based medical journal, estimated that more than 400,000 deaths a year in the U.S. are linked to lead exposure — or 18 percent of all deaths.

There is no federal standard for the amount of lead found in tap water at individual homes, but studies have reported harmful effects when concentrations exceed the FDA’s standard for bottled water. In a recent peer-reviewed study, EPA scientists cautioned that when children under age 7 drink water containing more than 5 ppb of lead on average, the amount of the metal in their blood can rise above CDC health guidelines.

Utilities are considered to be in compliance with federal water quality regulations as long as 90 percent of the homes tested have lead levels below 15 ppb, a standard the EPA set nearly three decades ago because the agency thought it could be met with corrosion-inhibiting chemicals. Chicago conducts this type of testing in just 50 homes every three years — the minimum required — and city officials say the results show residents have no cause for concern.

The Tribune first reported in 2016 that most of the Chicago homes tested for regulatory purposes were owned by water department employees or retirees living on the Far Northwest and Far Southwest Sides. The limited testing typically found little or no lead in tap water at those homes.

By contrast, the newspaper’s analysis of the more recent testing kit results revealed that lead-contaminated water was found in at least one home in all 77 Chicago community areas.

In Mount Greenwood, one of the same neighborhoods where the city conducts its EPA-mandated testing, the amount of lead in initial samples of water averaged 5.2 ppb among the 127 homes that submitted testing kits. Average first-draw concentrations of lead were even higher in 16 other community areas where at least 10 homes sent water samples to the city, including South Chicago (17.6 ppb), Chicago Lawn (16 ppb), New City, (14.3 ppb), Chatham (9.4 ppb) and Avondale (7.8 ppb).

Poverty's Poison: Our ongoing lead coverage Read more

Lead levels in samples sent by 129 homeowners in Beverly averaged 5.2 ppb after taps had been running for three minutes. Other community areas with high averages among second-draw samples: Forest Glen (6.1 ppb), West Pullman (5.8 ppb), Garfield Ridge (5.5 ppb), Morgan Park (5.4 ppb) and Washington Heights (5.3 ppb).

The samples collected by Chicagoans during the past two years provide more evidence that federal testing protocols vastly underestimate hazardous conditions in cities with lead service lines, said Yanna Lambrinidou, a Virginia Tech researcher who served on an EPA advisory panel that in 2015 called for an aggressive campaign of testing and public warnings until the pipes are removed.

“Chicago’s testing blows out of the water one of the foundations of (federal regulations), namely that current lead-in-water monitoring requirements yield reliable information about the extent and severity of contamination across a service area,” Lambrinidou said.

At more than 100 homes across the city where lead levels reached 15 ppb to 270 ppb in testing kit samples, water department officials conducted follow-up testing that involved drawing 10 consecutive 1-liter samples. Nearly all of those samples contained more than 5 ppb of lead, the Tribune analysis found, with levels generally increasing rather than decreasing as more water flowed out of the taps.

At Abrahamian’s Northwest Side bungalow, the first sample of unfiltered water collected by the department had significantly lower levels of lead than the amount in her own sample — 7.6 ppb, compared with 250 ppb. But by the 10th liter, the amount of lead had increased to 14.3 ppb. An additional sample collected after the water had been running another three minutes contained 24.8 ppb of lead — nearly five times higher than the FDA limit for bottled water.

The water department later sent Abrahamian a letter advising her to flush her plumbing regularly and to replace her kitchen faucet, citing her “longer than average service line and lower than average water usage.” Using more water “ensures optimal performance of corrosion inhibitors on metal services,” the letter concluded.

“It’s an expensive and intricate problem to solve,” Abrahamian said of the city’s vast network of lead service lines. “Should (replacing the lines) be the responsibility of the homeowner or landlord who has tenants with small children? Right now there is no accountability.”

Workers from the Chicago Department of Water Management install a new water main in the 3100 block of North Richmond Street on April 2, 2018. The city has been overhauling its aging water system. (Antonio Perez / Chicago Tribune)

Results from the sequential sampling mirror a trend EPA researchers noticed six years ago when they tested Chicago tap water after lead service lines had been jostled during the installation of new water mains — work that Emanuel is speeding up across the city.

It turns out the process of hooking new cast-iron mains to aging lead pipes can dramatically increase the chances otherwise-clean water is contaminated by the time it reaches a home, in particular if water has been stagnating in service lines for several hours.

Not only can street work shake loose the protective coating that lines lead pipes — city construction crews sometimes make the problem worse by splicing a length of copper pipe between the iron water main and lead service line, a practice Tribune reporters and photographers have seen firsthand. Studies have found the combination of metals can trigger an electrochemical reaction that corrodes the inside of lead pipes.

How to protect yourself from lead exposure in drinking water Read more

Miguel Del Toral, an EPA water expert who led the Chicago study and played a key role in exposing what went wrong in Flint, tells audiences that if their city still has lead service lines, the most effective way to immediately protect themselves is to filter their drinking water.

The filters don’t need to be as elaborate — or as expensive — as the system Abrahamian installed. NSF International, a nonprofit standards organization, publishes a consumer guide listing a variety of devices certified to remove lead.

Unlike Chicago, cities including Boston, Denver, Detroit, Milwaukee, Philadelphia, Pittsburgh and St. Paul, Minn., are adding service line replacements to municipal construction projects, beginning in low-income neighborhoods where childhood lead poisoning remains a persistent problem.

Some of the efforts are being funded through the same federal-state loan program Chicago is relying on to upgrade the public water system. Utilities also are moving to raising water rates to finance replacement programs, including Indiana American Water, a private company that serves several communities in northwest Indiana.

Milwaukee has estimated that digging up and replacing all of the city’s lead service lines would cost $750 million. Other cities are developing methods that are both less invasive and more cost-effective, or setting up programs to share replacement costs between municipalities and property owners.

Since Emanuel took office in 2011, Chicago has borrowed more than $481 million for water projects, including $312 million to install new water mains. The city has been steadily raising water rates to pay back the 20-year loans.

Chicagoans still pay less for drinking water than most other Americans, even after rates have doubled under Emanuel. But none of the money has been earmarked to replace lead service lines.

Chicago residents interested in having their tap water tested for lead can order a free testing kit from the city at www.chicagowaterquality.org.

mhawthorne@chicagotribune.com

creyes@chicagotribune.com

Twitter @scribeguy

Twitter @kcecireyes