Water Systems Over the Lead Action Level: 52 Now, 168 Under the 2027 Rule
The short answer
Of the 9,345 US community water systems serving more than 3,300 people that reported a lead result since 2021, 52 had a 90th-percentile lead level above today’s 15 µg/L action level, serving 1.31 million people, according to EPA’s Safe Drinking Water Information System. 168 systems serving 5.33 million people were above 10 µg/L, the action level that takes effect on 1 November 2027 under the Lead and Copper Rule Improvements. The median system’s 90th-percentile lead level was 1.0 µg/L.
The short answer, expanded
Under the Lead and Copper Rule, water systems sample taps in homes most likely to have lead plumbing and report the 90th-percentile result. If it is above the action level, the system must take action, including corrosion control and public education. EPA’s Lead and Copper Rule Improvements lower that action level from 15 µg/L to 10 µg/L, effective 1 November 2027, and change the sampling protocol. This report counts how many systems the existing data already place above each line.
One correction to how this data is often used: states are required to report every 90th-percentile result only for medium and large systems. For small systems serving 3,300 people or fewer, EPA no longer requests results at or below the action level, so small-system records over-represent exceedances. Rates in this report therefore cover systems serving more than 3,300 people, where reporting is complete.
| System size (people served) | Systems | Over 15 µg/L | Over 10 µg/L | People served by systems over 10 µg/L |
|---|---|---|---|---|
| 3,301 to 10,000 | 4,898 | 25 (0.5%) | 81 (1.7%) | 491,573 |
| 10,001 to 50,000 | 3,402 | 20 (0.6%) | 65 (1.9%) | 1,505,158 |
| 50,001 to 100,000 | 575 | 4 (0.7%) | 13 (2.3%) | 877,983 |
| More than 100,000 | 470 | 3 (0.6%) | 9 (1.9%) | 2,455,349 |
| All medium and large systems | 9,345 | 52 (0.6%) | 168 (1.8%) | 5,330,063 |
Source: EPA SDWIS federal data (Envirofacts tables LCR_SAMPLE_RESULT, LCR_SAMPLE and WATER_SYSTEM), each active community water system’s most recent lead 90th-percentile result for a monitoring period ending 2021 to 2025. Calculated by The Plumbing Brief. Population is as reported in SDWIS.
The evidence
- Lead 90th-percentile results in SDWIS: 283,784 records. Source: EPA Envirofacts.
- Active community water systems serving more than 3,300 people: 9,597; with a result for a period ending 2021 or later: 9,345. Source: EPA SDWIS, calculated.
- Above 15 µg/L: 52 systems (0.6 percent), serving 1,308,108 people. Source: calculated from EPA SDWIS.
- Above 10 µg/L: 168 systems (1.8 percent), serving 5,330,063 people. Source: calculated from EPA SDWIS.
- Median 90th-percentile lead level among these systems: 1.0 µg/L; 90 percent of systems were at or below 4.6 µg/L. Source: calculated.
- Small systems (3,300 people or fewer) with a reported result above 15 µg/L for a period ending 2021 or later: at least 465; a rate cannot be computed because non-exceeding small systems are not reported. Source: EPA SDWIS.
- The LCRI lowers the action level “from 15 µg/L to 10 µg/L” and requires systems to use the higher of first-liter and fifth-liter samples at lead service line sites. Source: EPA LCRI fact sheet.
By state
| State | Medium and large systems | Over 15 µg/L | Over 10 µg/L | Share over 10 µg/L |
|---|---|---|---|---|
| IL | 448 | 13 | 36 | 8.0% |
| WI | 180 | 0 | 11 | 6.1% |
| NE | 43 | 0 | 2 | 4.7% |
| MI | 291 | 5 | 13 | 4.5% |
| NY | 296 | 2 | 10 | 3.4% |
| IN | 208 | 0 | 6 | 2.9% |
| UT | 120 | 2 | 3 | 2.5% |
| SC | 161 | 1 | 4 | 2.5% |
| MA | 245 | 2 | 6 | 2.4% |
| KY | 219 | 0 | 5 | 2.3% |
| KS | 92 | 1 | 2 | 2.2% |
| OK | 143 | 2 | 3 | 2.1% |
| SD | 50 | 0 | 1 | 2.0% |
| MS | 201 | 1 | 4 | 2.0% |
| OR | 118 | 1 | 2 | 1.7% |
| NJ | 240 | 0 | 4 | 1.7% |
| MN | 189 | 2 | 3 | 1.6% |
| WA | 209 | 2 | 3 | 1.4% |
| NM | 71 | 0 | 1 | 1.4% |
| GA | 240 | 0 | 3 | 1.2% |
| AZ | 163 | 1 | 2 | 1.2% |
| NC | 278 | 2 | 3 | 1.1% |
| AL | 296 | 3 | 3 | 1.0% |
| MO | 220 | 0 | 2 | 0.9% |
| PA | 333 | 1 | 3 | 0.9% |
| FL | 380 | 1 | 3 | 0.8% |
| IA | 140 | 0 | 1 | 0.7% |
| TX | 1171 | 2 | 8 | 0.7% |
| CO | 148 | 0 | 1 | 0.7% |
| AR | 155 | 1 | 1 | 0.6% |
| OH | 313 | 0 | 2 | 0.6% |
| CA | 654 | 3 | 4 | 0.6% |
| LA | 250 | 0 | 1 | 0.4% |
| TN | 280 | 0 | 1 | 0.4% |
| VA | 149 | 0 | 0 | 0.0% |
| WV | 92 | 0 | 0 | 0.0% |
| CT | 60 | 0 | 0 | 0.0% |
| ID | 59 | 0 | 0 | 0.0% |
| MD | 56 | 0 | 0 | 0.0% |
States with at least 40 medium or large systems reporting. Other states are in the CSV. State differences partly reflect where lead service lines are concentrated.
What the numbers imply
The 2027 rule roughly triples the count over the line
Formula. Systems above 10 µg/L divided by systems above 15 µg/L, on current results.
Calculation. 168 / 52 = 3.2; people served 5.33 million against 1.31 million.
Finding. On today’s data the lower action level would bring about three times as many medium and large systems, and four times as many people, into required action. That is a lower bound, because the new fifth-liter sampling at lead service line sites is designed to find more lead than current first-draw samples.
Limitations. Exceedance under the new rule depends on sampling under the new protocol from 2027; current results are an indicator, not a prediction for any system.
Most systems are far below either line
Formula. Distribution of the latest 90th-percentile results.
Calculation. Median 1.0 µg/L; 90th percentile of systems 4.6 µg/L.
Finding. Exceedances are concentrated in a small number of systems; IL (36), MI (13), WI (11), NY (10) have the most systems above 10 µg/L. The national picture is mostly low lead levels with a long tail.
Limitations. A 90th-percentile result describes sampled high-risk homes, not average tap water.
Figures worth quoting
- 52 medium and large US water systems are above the current 15 µg/L lead action level, serving 1.3 million people.
- 168 are above the 10 µg/L level that applies from November 2027, serving 5.3 million.
- The median system’s 90th-percentile lead level is 1.0 µg/L.
Download the data
Counts, exceedances at 15 and 10 µg/L, populations and distribution statistics. Published under a Creative Commons Attribution 4.0 licence. Attribution: The Plumbing Brief.
Lead 90th-percentile results for medium and large community water systems, by size and state (CSV)
How this report was built
Methodology
Sources. EPA Safe Drinking Water Information System federal data via Envirofacts: LCR_SAMPLE_RESULT (contaminant PB90), LCR_SAMPLE (monitoring period dates) and WATER_SYSTEM (community water systems, population served, activity status, source), retrieved 4 October 2026. Rules from the EPA LCRI fact sheet and FAQ, and EPA LCR reporting guidance (Appendix B).
Selection. Active community water systems serving more than 3,300 people; for each, the most recent 90th-percentile lead result for a monitoring period ending between 1 January 2021 and 31 December 2025. Exceedance means a value greater than 0.015 mg/L or 0.010 mg/L.
Retrieval date. 4 October 2026.
Data limitations
- Small systems are excluded from rates because their non-exceeding results are not reported to EPA.
- SDWIS data depend on state reporting and can lag by a year or more.
- Results reflect the current sampling protocol; LCRI sampling from 2027 is expected to detect more lead.
- Systems are not named. A 90th-percentile exceedance triggers required actions, not a finding of a violation.
- Population served is as recorded in SDWIS and is not deduplicated for consecutive systems buying water from each other.
Source quality ranking
Tier 1. US EPA SDWIS federal data (Envirofacts); EPA Lead and Copper Rule Improvements fact sheet and FAQ; EPA LCR reporting guidance.
Tier 2. None used. Tier 3. None used.
Briefing note
52 US community water systems serving more than 3,300 people had a 90th-percentile lead level above the federal 15 µg/L action level in their most recent monitoring period, serving 1.31 million people, according to an analysis of EPA Safe Drinking Water Information System data by The Plumbing Brief. Under the 10 µg/L action level that takes effect in November 2027, 168 systems serving 5.33 million people would be above the line on current results. The analysis excludes small systems, whose results below the action level are not reported to EPA.
How reporters could frame this
- The new lead rule will put three times as many water systems over the line
- 5 million Americans are served by systems above the 2027 lead level
- Why small-system lead data overstates the problem
- Most water systems are well under the lead action level
Related questions
How many water systems exceed the lead action level? 52 medium and large community water systems were above 15 µg/L in their latest monitoring period (EPA SDWIS).
What is the new lead action level? 10 µg/L, down from 15 µg/L, under EPA’s Lead and Copper Rule Improvements, effective 1 November 2027.
How many systems would exceed the new level? 168 medium and large systems on current results, serving 5.33 million people.
What happens when a water system exceeds the action level? It must inform the public and take action to reduce lead exposure, such as installing or adjusting corrosion control, while replacing lead pipes.
Why are small water systems excluded? States do not report small systems’ results at or below the action level, so their data only show exceedances.
How to cite this report
The Plumbing Brief, “Water Systems Over the Lead Action Level: 52 Now, 168 Under the 2027 Rule”, https://theplumbingbrief.com/water-systems-over-lead-action-level/, accessed [date].
Last reviewed: 2026-10-04.
