Community Water System · PWS WI2680227
Oconomowoc Waterworks
Operator location Oconomowoc, Wisconsin - 31% of 26 violations are health-based (upper-third health share (> 23%)); groundwater source; 15,805 served per SDWIS.
- 15,805
- People served (this PWS)
- 26
- EPA violations (this PWS)
- 8
- Health-based (this PWS)
- 2 PFAS
- UCMR5 (this PWS)
Oconomowoc Waterworks standing, mid SDWIS violation third
31% of 26 recorded violations are health-based - upper-third health share (> 23%). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 31% is upper-third health share (> 23%). UCMR5: lower-third PFAS panel (≤ 2 compounds). Population rank #3,316 of 29,740 among systems serving 500+.
The verdict
Oconomowoc Waterworks lands in the middle third by violation volume (26), large enough for peer comparisons without matching the fleet's heaviest ledgers. Population served is large (15,805; larger served population (> 3,309)), so household exposure scale sits behind the violation mix. Health-based share is 31% - most of this ledger is MCL or treatment-technique exceedance. UCMR5 detected 2 PFAS compounds (lower-third PFAS panel (≤ 2 compounds)).
- #3,316 of 29,740
- Population · /systems
- #53 of 744
- Population · WI
- 26
- Total EPA violations on record
- 31%
- Health-based (MCL / treatment failure)
Population ordinals match the sitemap cohort (systems serving 500+, population_served DESC). See methodology · corpus placement.
2 PFAS "forever chemicals" detected in testing under EPA's UCMR5 monitoring program.
System Details
- System Type
- Community
- Owner Type
- Local
- Connections
- 1
- County
- Waukesha
- School/Daycare
- No
- MCL Violations
- 8
- Monitoring Violations
- 14
- Treatment Tech Violations
- 0
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| Coliform (TCR) | MCL | 8 | 2001 |
| TTHM | MR | 5 | 2014 |
| Total Haloacetic Acids (HAA5) | MR | 5 | 2014 |
| Lead and Copper Rule | MR | 4 | 2005 |
| Consumer Confidence Rule | Other | 3 | 2007 |
| Public Notice | Other | 1 | 2006 |
Violation Count vs. the National Corpus
Oconomowoc Waterworks has 26 recorded EPA violations, 38% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 61% carry more. 31% of this system's own violations are health-based (8 of 26), and it ranks #3,316 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)
26 Lower than most fewer violations than 61% 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. 4 of 232 samples detected PFAS.
| Contaminant | Date | Result | MRL | Status |
|---|---|---|---|---|
| PFTrDA | 9/27/2023 | <7.00 ppt | 7.00 ppt | Not Detected |
| PFTA | 9/27/2023 | <8.00 ppt | 8.00 ppt | Not Detected |
| NEtFOSAA | 9/27/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| NMeFOSAA | 9/27/2023 | <6.00 ppt | 6.00 ppt | Not Detected |
| PFMBA | 9/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHxA | 9/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpS | 9/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeS | 9/27/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| NFDHA | 9/27/2023 | <20.00 ppt | 20.00 ppt | Not Detected |
| PFEESA | 9/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 8:2 FTS | 9/27/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFMPA | 9/27/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| 6:2 FTS | 9/27/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFBA | 9/27/2023 | 5.40 ppt | 5.00 ppt | Detected |
| HFPO-DA | 9/27/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| ADONA | 9/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 9Cl-PF3ONS | 9/27/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| 4:2 FTS | 9/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFUnA | 9/27/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFDoA | 9/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDA | 9/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFOA | 9/27/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFOS | 9/27/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFNA | 9/27/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFHxS | 9/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpA | 9/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBS | 9/27/2023 | 4.50 ppt | 3.00 ppt | Detected |
| 11Cl-PF3OUdS | 9/27/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFPeA | 9/27/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFPeS | 9/18/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| 6:2 FTS | 9/18/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| 4:2 FTS | 9/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| 8:2 FTS | 9/18/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| PFMPA | 9/18/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFPeA | 9/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFMBA | 9/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| NFDHA | 9/18/2023 | <20.00 ppt | 20.00 ppt | Not Detected |
| PFHpS | 9/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFBA | 9/18/2023 | 5.20 ppt | 5.00 ppt | Detected |
| PFNA | 9/18/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| PFEESA | 9/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| HFPO-DA | 9/18/2023 | <5.00 ppt | 5.00 ppt | Not Detected |
| 9Cl-PF3ONS | 9/18/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFUnA | 9/18/2023 | <2.00 ppt | 2.00 ppt | Not Detected |
| PFHxA | 9/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFDoA | 9/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFOA | 9/18/2023 | <4.00 ppt | 4.00 ppt | Not Detected |
| ADONA | 9/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHxS | 9/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
| PFHpA | 9/18/2023 | <3.00 ppt | 3.00 ppt | Not Detected |
Health-based violations on Oconomowoc Waterworks
8 health-based rows in the tables above map to MCL or treatment-technique exceedances, verify each contaminant code on the federal SDWIS report for WI2680227.
Sources: EPA SDWIS · Wisconsin DNR, Drinking Water and Groundwater
Nationwide peers
26 violations · 15,805 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 Oconomowoc Waterworks
Use this system's EPA-reported record as a starting filter, not a final verdict.
- See how every tracked system in Wisconsin compares on the same EPA violation measures. Wisconsin 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.