Community Water System · PWS CO0107485
Longmont City Of
Operator location Longmont, Colorado - larger served population (> 3,309) at 102,866 people served; 78 SDWIS violations on record from surface water sources.
- 102,866
- People served (this PWS)
- 78
- EPA violations (this PWS)
- 2
- Health-based (this PWS)
- No PFAS
- UCMR5 (this PWS)
Longmont City Of standing, high SDWIS violation third
102,866 people served (SDWIS) - larger served population (> 3,309). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 3% is middle-third health share (≤ 23%). UCMR5: UCMR5 tested, none detected. Population rank #476 of 29,740 among systems serving 500+.
The verdict
Longmont City Of sits in the upper third of the sitemap cohort by violation count (78), so the tables below sample a dense compliance trail rather than a near-clean ledger. Population served is large (102,866; larger served population (> 3,309)), so household exposure scale sits behind the violation mix. Health-based share is 3% (middle-third health share (≤ 23%)). UCMR5 tested this system and reported no PFAS above the minimum reporting level.
- #476 of 29,740
- Population · /systems
- #14 of 551
- Population · CO
- 78
- Total EPA violations on record
- 3%
- Health-based (MCL / treatment failure)
Population ordinals match the sitemap cohort (systems serving 500+, population_served DESC). See methodology · corpus placement.
System Details
- System Type
- Community
- Owner Type
- Local
- Connections
- 29,697
- County
- Boulder
- School/Daycare
- No
- MCL Violations
- 0
- Monitoring Violations
- 75
- Treatment Tech Violations
- 2
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| TTHM | MR | 3 | 2022 |
| Total Haloacetic Acids (HAA5) | MR | 3 | 2022 |
| Endrin | MR | 2 | 2005 |
| Diquat | MR | 2 | 2005 |
| Endothall | MR | 2 | 2005 |
| Di(2-ethylhexyl) adipate | MR | 2 | 2005 |
| Di(2-ethylhexyl) phthalate | MR | 2 | 2005 |
| Picloram | MR | 2 | 2005 |
| Aldicarb sulfone | MR | 2 | 2005 |
| Carbofuran | MR | 2 | 2005 |
| Aldicarb | MR | 2 | 2005 |
| Atrazine | MR | 2 | 2005 |
| LASSO | MR | 2 | 2005 |
| 2,4-D | MR | 2 | 2005 |
| HEXACHLOROBENZENE | MR | 2 | 2005 |
| Benzo(a)pyrene | MR | 2 | 2005 |
| 1,2-DIBROMO-3-CHLOROPROPANE | MR | 2 | 2005 |
| ETHYLENE DIBROMIDE | MR | 2 | 2005 |
| Total Polychlorinated Biphenyls (PCB) | MR | 2 | 2005 |
| Dalapon | MR | 2 | 2005 |
| 2,4,5-TP | MR | 2 | 2005 |
| Simazine | MR | 2 | 2005 |
| Methoxychlor | MR | 2 | 2005 |
| Heptachlor | MR | 2 | 2005 |
| Aldicarb sulfoxide | MR | 2 | 2005 |
| Chlordane | MR | 2 | 2005 |
| Toxaphene | MR | 2 | 2005 |
| Heptachlor epoxide | MR | 2 | 2005 |
| Surface Water Treatment Rule | TT | 2 | 1995 |
| Dinoseb | MR | 2 | 2005 |
Violation Count vs. the National Corpus
Longmont City Of has 78 recorded EPA violations, 68% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 32% carry more. 3% of this system's own violations are health-based (2 of 78), and it ranks #476 of 29,740 by population served among that same cohort.
EPA violations vs. the national water-system corpus
Public water systems serving 500+ people (EPA SDWIS)
78 Around the middle fewer violations than 32% of 29,740 water systems
the national water-system corpus, bucketed by value
Each bar is a band; taller bars hold more water systems. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source EPA SDWIS · 2026-05-15
PFAS Testing Results (UCMR5)
Results from EPA's Fifth Unregulated Contaminant Monitoring Rule. 0 of 116 samples detected PFAS.
| Contaminant | Date | Result | MRL | Status |
|---|---|---|---|---|
| PFHpA | 8/7/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFUnA | 8/7/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFHxA | 8/7/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDoA | 8/7/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDA | 8/7/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFOA | 8/7/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFOS | 8/7/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 8/7/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFHxS | 8/7/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| NMeFOSAA | 8/7/2023 | <6.00 ppt | 6.00 ppt | Not Detected |
| NEtFOSAA | 8/7/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFHpS | 8/7/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFTrDA | 8/7/2023 | <7.00 ppt | 7.00 ppt | Not Detected |
| PFTA | 8/7/2023 | <8.00 ppt | 8.00 ppt | Not Detected |
| PFNA | 8/7/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFPeA | 8/7/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBS | 8/7/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| NFDHA | 8/7/2023 | <20.00 ppt | 20.00 ppt | Not Detected |
| 9Cl-PF3ONS | 8/7/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFMBA | 8/7/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeS | 8/7/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFMPA | 8/7/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| 8:2 FTS | 8/7/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| 4:2 FTS | 8/7/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 6:2 FTS | 8/7/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFBA | 8/7/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| HFPO-DA | 8/7/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| ADONA | 8/7/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFEESA | 8/7/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 4:2 FTS | 5/1/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHxA | 5/1/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 5/1/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| ADONA | 5/1/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| HFPO-DA | 5/1/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFEESA | 5/1/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 6:2 FTS | 5/1/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFOA | 5/1/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| 8:2 FTS | 5/1/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFMPA | 5/1/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFPeA | 5/1/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMBA | 5/1/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBA | 5/1/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFDA | 5/1/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 9Cl-PF3ONS | 5/1/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFOS | 5/1/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFNA | 5/1/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFHxS | 5/1/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpA | 5/1/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBS | 5/1/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| NMeFOSAA | 5/1/2023 | <6.00 ppt | 6.00 ppt | Not Detected |
Population served record for Longmont City Of
EPA SDWIS lists 102,866 people served and 29,697 connections for this PWS, confirm the service-area footprint on the federal report before comparing to municipal census totals.
Sources: EPA SDWIS · Colorado Department of Public Health and Environment, Water Quality Control
Nationwide peers
78 violations · 102,866 served: nearest cross-state SDWIS matches.
Cross-state systems with comparable violation load
Nearest cross-state community systems (500+ served) by total SDWIS violations on record.
Cross-state systems with similar served population
Nearest cross-state systems by EPA SDWIS population_served (same 500+ sitemap gate).
What to do with Longmont City Of
Use this system's EPA-reported record as a starting filter, not a final verdict.
- See how every tracked system in Colorado compares on the same EPA violation measures. Colorado systems
- Check whether PFAS was detected at this system under UCMR5 testing. PFAS guide
- Find and compare another public water system by name or PWSID. Search systems
EPA SDWIS and UCMR5 figures are informational only, not a substitute for a certified lab test of your own tap water.