Community Water System · PWS CA4100509
County Service Area 7
Operator location Redwood City, California - smaller served population (≤ 999) at 300 people served; 84 SDWIS violations on record from surface water sources.
- 300
- People served (this PWS)
- 84
- EPA violations (this PWS)
- 13
- Health-based (this PWS)
- Untested
- UCMR5 (this PWS)
County Service Area 7 standing, high SDWIS violation third
300 people served (SDWIS) - smaller served population (≤ 999). Corpus terciles use 29,740 systems serving 500+ (the sitemap cohort). Health-based share 15% is middle-third health share (≤ 23%).
The verdict
County Service Area 7 sits in the upper third of the sitemap cohort by violation count (84), so the tables below sample a dense compliance trail rather than a near-clean ledger. Population served is smaller (300; smaller served population (≤ 999)), so each violation row represents a compact service footprint. Health-based share is 15% (middle-third health share (≤ 23%)). No UCMR5 PFAS test appears for this system in this extract.
- 84
- Total EPA violations on record
- 15%
- Health-based (MCL / treatment failure)
- 300
- People served by this PWS (SDWIS)
- N/A
- PFAS compounds detected (UCMR5)
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
- 68
- County
- San Mateo
- School/Daycare
- No
- MCL Violations
- 12
- Monitoring Violations
- 45
- Treatment Tech Violations
- 1
Violation History
Contaminant violations recorded by EPA.
| Contaminant | Category | Count | Latest |
|---|---|---|---|
| TTHM | MCL | 8 | 2018 |
| Total Haloacetic Acids (HAA5) | MCL | 4 | 2025 |
| Toluene | MR | 2 | 2004 |
| Benzene | MR | 2 | 2004 |
| Ethylbenzene | MR | 2 | 2004 |
| DICHLOROMETHANE | MR | 2 | 2004 |
| Tetrachloroethylene | MR | 2 | 2004 |
| 1,1,1-Trichloroethane | MR | 2 | 2004 |
| 1,1,2-Trichloroethane | MR | 2 | 2004 |
| 1,2-Dichloroethane | MR | 2 | 2004 |
| o-Dichlorobenzene | MR | 2 | 2004 |
| 1,2-Dichloropropane | MR | 2 | 2004 |
| p-Dichlorobenzene | MR | 2 | 2004 |
| Vinyl chloride | MR | 2 | 2004 |
| Styrene | MR | 2 | 2004 |
| Xylenes, Total | MR | 2 | 2004 |
| Gross Alpha, Excl. Radon and U | MR | 2 | 1981 |
| Carbon tetrachloride | MR | 2 | 2004 |
| CHLOROBENZENE | MR | 2 | 2004 |
| 1,2,4-Trichlorobenzene | MR | 2 | 2004 |
| trans-1,2-Dichloroethylene | MR | 2 | 2004 |
| 1,1-Dichloroethylene | MR | 2 | 2004 |
| Trichloroethylene | MR | 2 | 2004 |
| cis-1,2-Dichloroethylene | MR | 2 | 2004 |
| Lead and Copper Rule | MR | 1 | 1993 |
| Surface Water Treatment Rule | TT | 1 | 1992 |
Violation Count vs. the National Corpus
County Service Area 7 has 84 recorded EPA violations, 69% of the 29,740 public water systems serving 500+ people nationwide carry fewer, and 30% carry more. 15% of this system's own violations are health-based (13 of 84), and it ranks unranked by population served among that same cohort.
EPA violations vs. the national water-system corpus
Public water systems serving 500+ people (EPA SDWIS)
84 Around the middle fewer violations than 30% 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
Population served record for County Service Area 7
EPA SDWIS lists 300 people served and 68 connections for this PWS, confirm the service-area footprint on the federal report before comparing to municipal census totals.
Sources: EPA SDWIS · California State Water Resources Control Board, Division of Drinking Water
Nationwide peers
84 violations · 300 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.
What to do with County Service Area 7
Use this system's EPA-reported record as a starting filter, not a final verdict.
- See how every tracked system in California compares on the same EPA violation measures. California 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.