Community Water System · PWS MT0000235
Hardin City Of
Operator location Hardin, Montana - larger served population (> 3,309) at 3,500 people served; 63 SDWIS violations on record from surface water sources.
- 3,500
- People served (this PWS)
- 63
- EPA violations (this PWS)
- 6
- Health-based (this PWS)
- No PFAS
- UCMR5 (this PWS)
Hardin City Of standing, mid SDWIS violation third
3,500 people served (SDWIS) - larger served population (> 3,309). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 10% is middle-third health share (≤ 23%). UCMR5: UCMR5 tested, none detected. Population rank #9,637 of 29,740 among systems serving 500+.
The verdict
Hardin City Of lands in the middle third by violation volume (63), large enough for peer comparisons without matching the fleet's heaviest ledgers. Population served is large (3,500; larger served population (> 3,309)), so household exposure scale sits behind the violation mix. Health-based share is 10% (middle-third health share (≤ 23%)). UCMR5 tested this system and reported no PFAS above the minimum reporting level.
- #9,637 of 29,740
- Population · /systems
- #36 of 283
- Population · MT
- 63
- Total EPA violations on record
- 10%
- 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
- 1,307
- County
- Big Horn
- School/Daycare
- No
- MCL Violations
- 0
- Monitoring Violations
- 37
- Treatment Tech Violations
- 6
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| CARBON, TOTAL | MR | 12 | 2004 |
| Consumer Confidence Rule | Other | 11 | 2013 |
| Total Haloacetic Acids (HAA5) | MR | 7 | 2025 |
| TTHM | MR | 7 | 2025 |
| Surface Water Treatment Rule | TT | 6 | 1995 |
| Coliform (TCR) | MR | 4 | 1996 |
| Arsenic | MR | 3 | 2000 |
| Lead and Copper Rule | MR | 2 | 2014 |
| CYANIDE | MR | 1 | 1994 |
| Asbestos | MR | 1 | 2002 |
Violation Count vs. the National Corpus
Hardin City Of has 63 recorded EPA violations, 63% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 37% carry more. 10% of this system's own violations are health-based (6 of 63), and it ranks #9,637 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)
63 Around the middle fewer violations than 37% 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 |
|---|---|---|---|---|
| PFTrDA | 9/17/2024 | <7.00 ppt | 7.00 ppt | Not Detected |
| PFBS | 9/17/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpA | 9/17/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHxS | 9/17/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFNA | 9/17/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFOS | 9/17/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFOA | 9/17/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFDA | 9/17/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDoA | 9/17/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHxA | 9/17/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFTA | 9/17/2024 | <8.00 ppt | 8.00 ppt | Not Detected |
| ADONA | 9/17/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFUnA | 9/17/2024 | <2.00 ppt | 2.00 ppt | Not Detected |
| HFPO-DA | 9/17/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFBA | 9/17/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| 6:2 FTS | 9/17/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| 4:2 FTS | 9/17/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| 8:2 FTS | 9/17/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFMPA | 9/17/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFPeA | 9/17/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMBA | 9/17/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFEESA | 9/17/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| NFDHA | 9/17/2024 | <20.00 ppt | 20.00 ppt | Not Detected |
| PFPeS | 9/17/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFHpS | 9/17/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 9/17/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| NEtFOSAA | 9/17/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| NMeFOSAA | 9/17/2024 | <6.00 ppt | 6.00 ppt | Not Detected |
| 9Cl-PF3ONS | 9/17/2024 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFEESA | 6/11/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| HFPO-DA | 6/11/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFBA | 6/11/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| 6:2 FTS | 6/11/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| 4:2 FTS | 6/11/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| 8:2 FTS | 6/11/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFMPA | 6/11/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFMBA | 6/11/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFUnA | 6/11/2024 | <2.00 ppt | 2.00 ppt | Not Detected |
| NFDHA | 6/11/2024 | <20.00 ppt | 20.00 ppt | Not Detected |
| PFPeS | 6/11/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFHpS | 6/11/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeA | 6/11/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| ADONA | 6/11/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| 11Cl-PF3OUdS | 6/11/2024 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFTrDA | 6/11/2024 | <7.00 ppt | 7.00 ppt | Not Detected |
| PFHxA | 6/11/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDoA | 6/11/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDA | 6/11/2024 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFOA | 6/11/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFOS | 6/11/2024 | <4.00 ppt | 4.00 ppt | Not Detected |
Population served record for Hardin City Of
EPA SDWIS lists 3,500 people served and 1,307 connections for this PWS, confirm the service-area footprint on the federal report before comparing to municipal census totals.
Sources: EPA SDWIS
Nationwide peers
63 violations · 3,500 served: nearest cross-state SDWIS matches.
Cross-state systems near this violation count
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 Hardin City Of
Use this system's EPA-reported record as a starting filter, not a final verdict.
- See how every tracked system in Montana compares on the same EPA violation measures. Montana 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.