Public water system · CA4900680

Active

Horicon School

At a glance

Horicon School (PWSID CA4900680) is an active non-transient non-community water system in Sonoma County, California. It reports serving 100 people through 4 service connections. Its primary water source is surface water, and EPA lists it as owned by a local government. EPA's records list 10 violations for this system; 4 are health-based, and the most recent began in October 2011.

Dataset updated October 2026 . Source: EPA SDWIS/ECHO public records.

Population served

100

Service connections

Primary source

Surface water

System type

NTNCWS

Non-transient non-community water system

System record

PWSIDCA4900680

System typeNon-transient non-community water system

Activity statusActive

Population served100

Service connections4

Primary water sourceSurface water

Owner typeLocal government

Primacy agencyCA state drinking water program

City served—

StateCalifornia

ZIP—

CountySonoma County

How does Horicon School compare with other water systems in Sonoma County?

By EPA's size categories, Horicon School is a very small system (500 people or fewer). Sonoma County has 441 active public water systems. Its population served is well below the county average of 1,092 people per system, and accounts for less than 0.1% of the 481,435 people reported by systems filed under the county. Across California, the 7,479 active systems average 5,706 people each. Nationally, the average active non-transient non-community water system reports serving 430 people, so Horicon School is well below that figure.

What does “non-transient non-community water system” mean?

A non-transient non-community water system regularly serves at least 25 of the same people for more than six months a year, but not where they live. Schools, factories, office buildings and hospitals with their own supply are typical examples. California has 1,466 active non-transient non-community water systems, 20% of the state's 7,479 active systems. Surface water means the system draws its water from rivers, lakes, streams or reservoirs. 609 California systems (8.1%) list surface water as their primary source.

Who owns and regulates Horicon School?

EPA lists Horicon School as owned by a local government. The CA state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 58 of the 441 active systems in Sonoma County (13%) are also owned by a local government.

Does Horicon School have drinking water violations?

EPA's records list 10 violations for this system; 4 are health-based, and the most recent began in October 2011. The violations listed here began between August 1984 and October 2011. By type: 5 monitoring and reporting, 4 contaminant level above the legal limit and 1 public notice, recordkeeping or other. The contaminant or rule involved most often is Total coliform bacteria (TCR) (6 of them). EPA lists 9 as resolved and 1 as archived. Resolved means at least one resolving action is on record: the system returned to compliance, the rule no longer applies, or no further action was needed. Archived means the violation was not marked resolved but is more than five years past the end of the noncompliance period, so it no longer counts toward current compliance status.

Began	Violation	Contaminant or rule	Health-based	Status
2011-10-01	Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02	Haloacetic acids (HAA5)code 2456	Yes	Resolved
2011-07-01	Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02	Haloacetic acids (HAA5)code 2456	Yes	Resolved
2010-12-01	Monitoring and reportingMonitoring of Treatment (SWTR-Filter) · code 36	Surface Water Treatment Rulecode 0200	No	Resolved
2008-03-01	Monitoring and reportingMonitoring, Repeat Minor (TCR) · code 26	Total coliform bacteria (TCR)code 3100	No	Resolved
2001-05-01	Monitoring and reportingMonitoring, Routine Major (TCR) · code 23	Total coliform bacteria (TCR)code 3100	No	Resolved
1998-09-01	Contaminant level above the legal limitMaximum Contaminant Level Violation, Acute (TCR) · code 21	Total coliform bacteria (TCR)code 3100	Yes	Resolved
1998-06-01	Monitoring and reportingMonitoring, Routine Major (TCR) · code 23	Total coliform bacteria (TCR)code 3100	No	Resolved
1997-10-01	Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22	Total coliform bacteria (TCR)code 3100	Yes	Resolved
1995-03-01	Monitoring and reportingMonitoring, Repeat Major (TCR) · code 25	Total coliform bacteria (TCR)code 3100	No	Resolved
1984-08-01	Public notice, recordkeeping or otherNotification, Public · code 06	Not reported	No	Archived

All 10 violations in EPA's records, newest first.Labels and codes come from EPA's SDWIS reference tables. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found. "Health-based" marks violations of a legal limit or required treatment.

Horicon School: frequently asked questions

Who runs Horicon School?

Horicon School (PWSID CA4900680) is a non-transient non-community water system owned by a local government. It is regulated by the CA state drinking water program.

How many people does Horicon School serve?

Horicon School reports serving 100 people through 4 service connections in Sonoma County, California.

Where does Horicon School get its water?

EPA SDWIS lists this system's primary water source as surface water. Surface water means the system draws its water from rivers, lakes, streams or reservoirs.

Does Horicon School have any drinking water violations?

EPA's records list 10 violations for this system; 4 are health-based, and the most recent began in October 2011. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found.

Is Horicon School's water safe to drink?

AquaCensus shows EPA compliance records, not current water test results, so it cannot say whether the water is safe at a given moment. EPA's records list 10 violations for this system; 4 are health-based, and the most recent began in October 2011. For current results, consult EPA ECHO, or the CA state drinking water program.

Where can I find Horicon School's water quality report?

The annual Consumer Confidence Report requirement applies to community water systems. Horicon School is a non-transient non-community water system, so it is not required to publish one; like every public water system, it must notify the people it serves about violations under EPA's public notification rules.

Other water systems in Sonoma County

Water system	County	Population served	Type	Source
Santa Rosa, City of	Sonoma	175,396	Community	Groundwater
Petaluma, City of	Sonoma	60,781	Community	Groundwater
Rohnert Park, City of	Sonoma	43,821	Community	Groundwater
Windsor, Town of	Sonoma	25,561	Community	Groundwater
Valley of the Moon Water District	Sonoma	23,107	Community	Groundwater
Sonoma, City of	Sonoma	11,725	Community	Groundwater

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About this data

Source: U.S. EPA Safe Drinking Water Information System (SDWIS) and SDWA violation records, via EPA ECHO, as published October 1, 2026 — AquaCensus refreshes it quarterly. See the methodology for how records are matched, cleaned and scored.

Cite as: AquaCensus, “Horicon School, PWSID CA4900680, California”, https://aquacensus.com/water-systems/california/horicon-school-ca4900680 (data as of October 1, 2026).