The Last Mile

Where this started

When Flint hit the headlines in 2016, most people saw a political problem. I saw a data problem. The people who needed to know what was in their water didn't have the information, and nobody had made it easy to find. So I asked the question I ask about everything: why isn't there an app for that?

I started pulling public water quality records for all 50 states into one database and built it so a non-technical person could read it. Put in your ZIP code and see what's in your water, what it means for your health and what kind of filter fits.

But even then, I knew the ZIP code wasn't the finish line. In 2019 I wrote this:

"Right now Aquagenuity can already tell you exactly what's in your water, down to the zip code level. But we want to do it down to the individual faucet: the water we drink, cook with, and bathe our children with."

We called it The Last Mile Project. Seven years later, it's still the most important problem in American drinking water data. Here's why.

What the public record covers

Your utility's job runs from the source to the street. It treats the water, tests it on a federal and state schedule, and publishes the results in its annual Water Quality Report. That work is thorough, it's regulated, and it's done by people who take it seriously.

Then the water leaves the main.

In Atlanta, the City's Department of Watershed Management owns the service line from the water main to the meter. From the meter to the building, the line belongs to the property owner, and so does everything inside: the plumbing, the solder, the fixtures, the faucet. Where the line splits varies from city to city, but nearly everywhere, the plumbing inside a building belongs to its owner.

That's not a loophole. It's how property works. But it means the last stretch of pipe your water touches is the stretch the public record sees least.

How much of the Last Mile gets tested

Lead is the clearest example, because lead mostly comes from the Last Mile, not the treatment plant.

Federal rules tell utilities how many homes to sample for lead. A system serving more than 100,000 people samples 100 homes per monitoring round, or 50 if it's earned reduced monitoring. That's the same for a city of 150,000 and a city of 1.5 million.

The City of Atlanta's water system serves about 1.09 million people. At 100 homes per round, that's about one home for every 11,000 people; at 50, about one for every 22,000.

That isn't a shortcut anyone took. It's the federal design, and it was built to answer one question well: is corrosion control working across the system? It wasn't built to tell you what's coming out of your tap. Atlanta's 2024 results were well within the federal action level: 90% of samples at or below 1.4 parts per billion. And the City has reported that it hasn't found a single lead service line. That's genuinely good news.

It still leaves the inside of nearly every building unmeasured, in Atlanta and across the country.

What lives in the Last Mile

Even with no lead service line, lead can come from inside a building:

• Older solder. Lead solder was banned in drinking water plumbing in 1986, and states had until 1988 to enforce the ban. Homes built before then may still have it.
• "Lead-free" fixtures that weren't. Until January 2014, "lead-free" pipes and fittings could legally contain up to 8% lead. Today the limit is 0.25%.
• Water that sits. Water that sits in pipes for hours, over a weekend or across a school summer, picks up more of whatever its pipes contain.

And it isn't only lead. Main breaks, pressure drops, building plumbing that's rarely flushed, and changes upstream can all show up at the tap.

Schools show the gap most clearly. When Georgia offered schools and child care centers free, federally funded lead testing, 96 of more than 5,400 eligible facilities had signed up by late 2022. Among the facilities tested, 37% had at least one tap beyond 15 parts per billion. As of January 2026, fewer than one in four Georgia public schools had enrolled in the federally funded testing program. In Georgia, school testing is voluntary, and some districts have done it on their own. Starting in November 2027, federal rules will require water systems to test schools and child care centers.

The research gap is getting wider

The science that tells us what to look for, and where, comes in large part from federal research. On July 18, 2025, EPA announced it was eliminating its Office of Research and Development, the agency's science arm, as part of a reorganization that cut about 3,700 positions agency-wide. A new office now sits inside the Administrator's office.

There's help coming on lead. The Lead and Copper Rule Improvements, finalized in October 2024, require utilities to replace lead service lines within 10 years and lower the lead action level from 15 to 10 parts per billion. Most requirements take effect November 1, 2027, and EPA is defending the rule in federal court.

That's real progress on the utility's side of the meter. The inside of the building is still mostly up to the people who live, learn and work there.

Who fills the gap

We do, together. That's the whole idea behind the Guardians of H2O™.

Guardians are students and families who test America's water in the Last Mile, from the curb to the tap. Every test they run is a data point the public record has never had. Together, those data points power what we've been building toward since 2019: real-time water quality monitoring, down to the faucet.

The AquaScore™ puts every public record about your water in one place, against both legal limits and health goals, with sources and dates.

AquaAlert™ watches for change. Think of it like ADT for water: it doesn't tell you your neighborhood is dangerous. It watches, and if something changes, you're the first to know. We alert. Officials declare.

And for utilities and cities, Last Mile data is an asset. It shows where to look, where to flush, where to sample next and where to send help first. Our goal is to put it in your hands first.

What you can do this week

• Test your own tap through a state-certified lab, especially if your home was built before 1986.
• Use cold water for drinking, cooking and baby formula, and run the tap until it's cold after water has sat for hours.
• If you use a filter, choose one certified by NSF® or another accredited body to reduce lead.
• Ask your school or child care center when its taps were last tested for lead, and ask for the results in writing.
• Become a Guardian. It's free.

The bottom line

You can't have a smart city without smart water. The public record gets the water to the curb. The Last Mile is where it gets into your glass, and it's where we're going next.

Water is not a political issue. It's a human issue.

Check your water at aquagenuity.com. Become a Guardian. It's free.

Next in this series: How the AquaScore™ works.

Sources

1. Doll Avant, The Last Mile Project, Aquagenuity program application, 2019 (author's own text, quoted).
2. Service line ownership (City owns main to meter; customer owns meter to building inlet) and "has not found a single lead service line": City of Atlanta Department of Watershed Management news release, Dec. 3, 2025. https://atlantawatershed.org/dwmnewsrelease-dec-3-2025/
3. Lead tap sampling: 100 sites for systems serving more than 100,000 people, 50 under reduced monitoring. 40 CFR 141.86, eCFR, accessed Oct. 14, 2026.
4. City of Atlanta population served, 1,089,893: EPA SDWIS via mytapwater.org, accessed Oct. 14, 2026. (1,089,893 ÷ 100 ≈ 10,900; ÷ 50 ≈ 21,800 people per sampled home.)
5. Atlanta 2024 home-tap lead results (90th percentile 1.4 ppb): City of Atlanta DWM, 2025 Water Quality Report.
6. Lead solder ban (1986 Safe Drinking Water Act Amendments) and "lead-free" redefined from 8% to 0.25% weighted average (Reduction of Lead in Drinking Water Act, effective Jan. 4, 2014): EPA, "Use of Lead Free Pipes, Fittings, Fixtures, Solder and Flux for Drinking Water."
7. Georgia's federally funded free lead testing (Clean Water for Georgia Kids): 96 of 5,400+ schools and day cares enrolled; 30 of tested facilities (37%) had a tap beyond 15 ppb. GPB, Jan. 5, 2023. https://www.gpb.org/news/2023/01/05/georgia-offered-schools-money-test-their-water-for-lead-most-didnt-sign-why
8. Fewer than one in four Georgia public schools enrolled in the program; testing is voluntary in Georgia: NPR, Jan. 27, 2026. https://www.wfae.org/2026-01-27/despite-free-testing-some-schools-have-been-slow-to-check-for-lead-in-their-water
9. EPA eliminates its Office of Research and Development, announced July 18, 2025; about 3,700 positions cut agency-wide; replaced by the Office of Applied Science and Environmental Solutions (Sept. 22, 2025 memo). Sabin Center for Climate Change Law, Columbia Law School. https://climate.law.columbia.edu/content/epa-eliminates-office-research-and-development-will-cut-over-3700-staff
10. Lead and Copper Rule Improvements: final Oct. 8, 2024; 10-year service line replacement; action level lowered to 10 ppb; compliance Nov. 1, 2027; school and child care testing required from that date. EPA, accessed Oct. 15, 2026. EPA is defending the rule in the D.C. Circuit (notice Feb. 20, 2026; final brief Apr. 17, 2026): NRDC case page, https://www.nrdc.org/court-battles/american-water-works-association-et-v-epa-lead-and-copper-rule-improvements

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