Thomson, IL · PWSID IL0150350
Thomson lead service lines
55 lead or galvanized lines to replace
Thomson reported 8 lead and 47 galvanized-requiring-replacement service lines out of 284 in its inventory. That's 19% of all its lines. Another 137 (48%) are still listed as unknown material.
Ranks #238 of 397 Illinois systems with confirmed lead lines, and #2,527 nationally.
19% of Thomson's service lines are lead or galvanized requiring replacement. That's about the same as the Illinois average (17%) and higher than the national average (3.1%).
- Lead 2.8%
- Galvanized (replace) 17%
- Unknown 48%
- Non-lead 32%
Total service lines reported: 284. Reported all required service line types. Population served: 600; 257 connections.
Lead test results
Thomson's most recent 90th-percentile lead result (Jan 2022–Dec 2024) was 0.6 ppb, below both the 15 ppb action level and the 10 ppb level that takes effect in 2027. This means 90% of homes sampled were at or below that level; individual homes, especially those with lead lines, can be higher.
Lead and Copper Rule 90th-percentile results reported to EPA, in parts per billion. Dashed lines: 15 ppb action level and the 10 ppb level from November 1, 2027.
Progress since 2025 Q1
Reported lead and galvanized-requiring-replacement lines went from 0 in 2025 Q1 to 55 in 2026 Q3: up 55. Lines of unknown material went from 0 to 137, up 137.
Quarterly counts reported to EPA. A drop usually means lines were replaced or confirmed non-lead; a rise usually means more lines were identified. Replacement progress rankings.
Lead rule violations
EPA's data lists no Lead and Copper Rule violations for Thomson since 2015. That covers testing, reporting, corrosion control and public notice requirements; it isn't a guarantee about any individual home.
Source: EPA SDWIS violation records for the Lead and Copper Rule.
Where the water comes from
Thomson's main water source is groundwater (wells). It buys treated water from Thomson Maximum Security Center. The seller treats the water, including corrosion control that keeps lead from dissolving out of pipes, while Thomson is responsible for its own service line inventory and replacement program. It sells water to 1 other water system: Thomson Maximum Security Center.
Source: EPA SDWIS water system and facility records.
Check your own address
These counts cover the whole system. To see whether your line is lead, use the utility's address-level inventory. Utilities had to prepare one by October 16, 2024 and make it publicly accessible; systems serving more than 50,000 people must post it online.
No map yet? Do the 2-minute scratch and magnet test on the pipe where water enters your home.
Protect your drinking water now
If your line is lead, galvanized or unknown, filter water for drinking, cooking and baby formula. Use a filter certified to NSF/ANSI 53 for lead. Run cold water for a few minutes after it sits for hours, and never use hot tap water for cooking.
How to pick a lead-certified filter · How to test your water for lead
Getting the line replaced
EPA's Lead and Copper Rule Improvements require most systems to replace lead and galvanized-requiring-replacement lines by December 31, 2037. Ask Thomson whether it replaces the private side for free or with a cost share before you hire anyone. If you want it done sooner, or your utility doesn't cover your side, a licensed plumber can quote it. What replacement costs.
County pages: Lead pipes in Carroll County
Cities served
Other water systems nearby
| System | Lead + galv. | Unknown |
|---|---|---|
| Savanna | 190 | 171 |
| Thomson Maximum Security Center | 0 | 0 |
| Lanark | 168 | 18 |
| Mount Carroll | 0 | 0 |
| Shannon | 10 | 6 |
Check another water system
Questions
Does Thomson have lead pipes?
Yes. Thomson reported 8 lead service lines and 47 galvanized lines that must be replaced, out of 284 total. 137 more are of unknown material.
How do I check if my home's service line is lead?
Look up your address on Thomson's official service line inventory, which utilities must make publicly available. You can also scratch the pipe where it enters your home: lead is soft, dull gray, scratches to shiny silver and does not attract a magnet.
When will Thomson replace lead service lines?
Under EPA's Lead and Copper Rule Improvements, most systems must replace lead and galvanized-requiring-replacement lines by December 31, 2037, starting from November 1, 2027. The rule is being challenged in court, so dates could change. Many utilities run free or cost-share programs now.
Has Thomson had lead violations?
EPA's data shows no Lead and Copper Rule violations since 2015 for Thomson.
Which water filters remove lead?
Use a filter certified to NSF/ANSI Standard 53 for lead reduction, or NSF/ANSI 58 for reverse osmosis. Check the certification on NSF's listings, not just the box.
Embed or cite this data
Local news sites, blogs and community groups can embed this card. It updates when EPA releases new data.
Citation: Lead Pipe Map, "Thomson lead service lines," https://leadpipemap.com/il/thomson/. Source: EPA SDWIS service line inventory, 2026 Q3. Download the full dataset on the data page.