Public water system · CA5210005
ActiveRio Alto Water District
At a glance
Rio Alto Water District (PWSID CA5210005) is an active community water system in Tehama County, California. It reports serving 3,329 people through 1,433 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. EPA's records list 5 violations for this system; 2 are health-based, and the most recent began in April 2015.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
3,329
Service connections
1,433
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Rio Alto Water District compare with other water systems in Tehama County?
By EPA's size categories, Rio Alto Water District is a medium system (3,301 to 10,000 people). Tehama County has 109 active public water systems, and Rio Alto Water District is the 3rd-largest of them by population served. Its population served is about 7 times the county average of 474 people per system, and accounts for 6.4% of the 51,627 people reported by systems filed under the county. Across California, the 7,479 active systems average 5,706 people each. Nationally, the average active community water system reports serving 6,703 people, so Rio Alto Water District is about half of that figure.
What does “community water system” mean?
A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. California has 2,997 active community water systems, 40% of the state's 7,479 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 6,179 California systems (83%) list groundwater as their primary source.
Who owns and regulates Rio Alto Water District?
EPA lists Rio Alto Water District 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. 22 of the 109 active systems in Tehama County (20%) are also owned by a local government.
Does Rio Alto Water District have drinking water violations?
EPA's records list 5 violations for this system; 2 are health-based, and the most recent began in April 2015. The violations listed here began between July 1993 and April 2015. By type: 3 monitoring and reporting and 2 contaminant level above the legal limit. The contaminant or rule involved most often is Total coliform bacteria (TCR) (4 of them). EPA lists 5 as resolved. 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.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2015-04-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2012-05-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 2010-11-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 2004-01-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
| 1993-07-01 | Monitoring and reportingInitial Tap Sampling for Pb and Cu · code 51 | Lead and Copper Rulecode 5000 | No | Resolved |
All 5 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.
Rio Alto Water District: frequently asked questions
Who runs Rio Alto Water District?
Rio Alto Water District (PWSID CA5210005) is a community water system owned by a local government. It is regulated by the CA state drinking water program.
How many people does Rio Alto Water District serve?
Rio Alto Water District reports serving 3,329 people through 1,433 service connections in Tehama County, California.
Where does Rio Alto Water District get its water?
EPA SDWIS lists this system's primary water source as groundwater. Groundwater means the system draws its water from wells or springs fed by underground aquifers.
Does Rio Alto Water District have any drinking water violations?
EPA's records list 5 violations for this system; 2 are health-based, and the most recent began in April 2015. 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 Rio Alto Water District'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 5 violations for this system; 2 are health-based, and the most recent began in April 2015. For current results, consult the system's annual water quality report, EPA ECHO, or the CA state drinking water program.
Where can I find Rio Alto Water District's water quality report?
As a community water system, Rio Alto Water District must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1 each year, covering the previous calendar year. The system can provide a copy on request.
Other water systems in Tehama County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| City of Red Bluff | Tehama | 14,710 | Community | Groundwater |
| City of Corning | Tehama | 8,244 | Community | Groundwater |
| Caltrans-Red Bluff Rest-Nb | Tehama | 2,600 | Transient non-community | Groundwater |
| Caltrans-Red Bluff Rest-Sb | Tehama | 2,500 | Transient non-community | Groundwater |
| Los Molinos Comm. Services Dist. | Tehama | 1,450 | Community | Groundwater |
| Gerber Las Flores Csd | Tehama | 1,200 | 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, “Rio Alto Water District, PWSID CA5210005, California”, https://aquacensus.com/water-systems/california/rio-alto-water-district-ca5210005 (data as of October 1, 2026).