Tapcensus

California

Ventura County drinking water quality

95 active public water systems serve 875,995 people in Ventura County. 58 are compliant, 37 had at least one EPA violation in the past three years, 0 are designated serious violators, and 17 carry a health flag.

Active systems 95 68 community systems
People served 876K by public water systems
Systems with violations 37 39% of active systems, past 3 years
Serious violators 0 17 systems carry a health flag

Needs attention

Rio Mesa High School/oxnard Uhs CA5602407 · Non-Transient non-community system · Serves 2,600 1 rule violated in the past three years. Unresolved: Lead and Copper Rule Revisions.
Vineyard Avenue Acres Mwc CA5610029 · Community water system · Serves 1,820 2 rules violated in the past three years. Unresolved: Lead and Copper Rule Revisions and Consumer Confidence Rule.
Vineyard Ave Estates Mwc CA5610056 · Community water system · Serves 1,200 1 rule violated in the past three years. Unresolved: Lead and Copper Rule Revisions.
Siete Robles Mutual Water CO CA5601119 · Community water system · Serves 323 1 rule violated in the past three years. Unresolved: Lead and Copper Rule Revisions.
Casitas Mutual Water Company CA5601104 · Community water system · Serves 238 2 rules violated in the past three years. Unresolved: Lead and Copper Rule and Lead and Copper Rule Revisions.
Del Norte Mutual Water Co. CA5602104 · Community water system · Serves 215 3 rules violated in the past three years. Unresolved: Lead and Copper Rule Revisions.
Navalair Mobile Home Park CA5602110 · Community water system · Serves 160 1 rule violated in the past three years. Unresolved: Lead and Copper Rule Revisions.
Siesta Mobile Home Park CA5602109 · Community water system · Serves 160 2 rules violated in the past three years. Unresolved: Lead and Copper Rule Revisions.
Elkins Ranch CA5601134 · Community water system · Serves 150 2 rules violated in the past three years. Unresolved: Lead and Copper Rule Revisions.
Nishi Quality Flowers, Inc. CA5603116 · Non-Transient non-community system · Serves 92 1 rule violated in the past three years. Unresolved: Lead and Copper Rule Revisions.

7 more systems with a serious violator or health flag designation are in the lists below.

Community water systems

68 systems, largest first
SystemServesStatusRules violated, 3 yrUnresolved
Oxnard Water Dept
 200,232 0 0
Ventura Water Department
 112,285 0 0
Ventura Wwd No. 8 Simi Valley
 94,736 0 0
Cal American Water CO
 66,809 0 0
City of Thousand Oaks Water Department
 54,770 0 0
Camarillo Water Dept
 47,701 0 0
Golden State Water Company Simi Valley
 45,086 0 0
Ventura Cwwd No. 1 Moorpark
 35,514 0 0
Camrosa Water District
 32,700 0 0
City of Santa Paula
 31,786 0 0
Port Hueneme City Water Dept
 21,582 1 0
California Water Service CO Westlake
 19,544 0 0
Fillmore Water Dept
 16,419 1 0
Triunfo Water & Sanitation District
 13,898 0 0
Casitas Municipal Water Dist
 11,005 2 0
Ojai Water System
 6,801 0 0
Ventura River Water District
 6,100 1 0
Pleasant Valley Mutual Water CO
 5,306 1 0
Channel Islands Beach Csd
 5,011 0 0
Meiners Oaks Cwd
 4,200 0 0
Naval Base Ventura County, Port Hueneme
 3,500 0 0
Crestview Mutual Water CO
 2,079 0 0
Cal American WC las Posas Estates
 2,043 0 0
Cal American Water Company Piru
 2,023 0 0
Ventura Cwwd No. 17 Bell Canyon
 1,946 0 0
Vineyard Avenue Acres Mwc
 1,820 2 2
Ventura Cwwd No. 38 Lake Sherwood
 1,759 0 0
Cal American WC Rio Plaza
 1,712 0 0
Naval Base Ventura County, Point Mugu
 1,700 1 0
Ventura Cwwd No. 19 Somis
 1,429 0 0
Garden Acres Mutual Water CO
 1,335 0 0
Vineyard Ave Estates Mwc
 1,200 1 1
Dempsey Road Mutual Water CO
 990 0 0
Rio Manor Mutual Water CO
 983 0 0
Nyeland Acres Mutual Water CO
 975 2 0
Limoneira Ranch #1
 813 0 0
Senior Canyon Mutual Water CO
 800 1 0
Cal American Yerba Buena
 690 0 0
Brandeis Bardin Institute
 665 2 1
Rancho Sespe Workers Imp Assoc
 600 1 0
Cloverdale Mutual Water Co.
 455 1 0
Strickland Mutual Water Company
 429 0 0
Saviers Road Mutual Water CO
 368 0 0
Sisar Mutual Water CO
 363 0 0
Fillmore Irrigation CO
 353 0 0
Siete Robles Mutual Water CO
 323 1 1
Casitas Mutual Water Company
 238 2 2
Cypress Mutual Water CO INC
 224 0 0
Del Norte Mutual Water Co.
 215 3 1
Saticoy Country Club-City of Ventura
Ventura 		196 1 0
Non-community systems (27: schools, campgrounds, workplaces, restaurants)

These systems serve places people visit rather than homes.

SystemServesStatusRules violated, 3 yrUnresolved
Smith Forks Water System
 3,000 1 0
Rio Mesa High School/oxnard Uhs
 2,600 1 1
Lake Piru Park Uwcd
 960 0 0
Rio School Dist/rio del Valle School
 820 0 0
Rio School Dist/ Rio Real School
 550 0 0
Usfs Wheeler Gorge Campground
 500 0 0
Glass House Camarillo Cultivation, LLC
 450 0 0
Thomas Aquinas College
 382 1 0
Laguna Vista School/oceanview School Dis
 377 0 0
Vineyard Mutual Water Company/industrial
 259 0 0
Foxfield Riding School
 120 0 0
Dennison Park
 102 1 0
Bouquet Multimedia
 100 0 0
Ventura Farms
 100 0 0
Nishi Quality Flowers, Inc.
 92 1 1
The Ranch at Live Oak
 82 1 1
GP Anacapa Foods, Llc.
 50 0 0
Santa Clara School
 39 0 0
Oxnard Pallet Company
 38 1 0
Beedy Water Company, LLC
 35 0 0
Camp Scheideck
 33 1 1
Channel Islands National Park
 30 0 0
Pyramid Flowers
 30 1 0
Santa Clara Resources
 30 1 0
Vulcan Materials Company Cal Mat
 30 1 1
Usfs Chuchupate Ranger Station
 26 1 1
State Ready Mix, Inc.
Ventura 		25 1 1
Inactive systems (83, no longer operating or reporting)

Kept for the record and excluded from the county totals above. Browse inactive systems.

About this data

Totals cover active systems. Systems serving more than one county are counted in each county. EPA counts the rules a system was in violation of, not the individual violations; one rule can carry several.

Source: the U.S. EPA's Enforcement and Compliance History Online system (ECHO), which publishes the federal Safe Drinking Water Information System. EPA's terms and values are shown as published. The California records are from EPA's data refresh of Oct 7, 2026; EPA refreshes this data quarterly, and states report to EPA with a lag of three to six months, so the newest violations may not appear yet. Retrieved from ECHO on Oct 11, 2026.