Tapcensus

Water quality in San Marcos, California

San Marcos is in San Diego County. 198 active public water systems serve the county; 83 had an EPA violation in the past three years.

Most likely your provider

Vista Irrigation District CA3710027 · Community water system · Surface water
Serves 134,501 people Rules violated, past 3 years 0 Last sanitary survey Nov 28, 2023 Distance 5.2 mi

Your location is within the outer bounds of this system's EPA service area.

View system details EPA facility report

Other community water systems in San Diego County

81 systems, nearest first
SystemServesStatusRules violated, 3 yrDistance
Vallecitos WD
 114,700 1 1.6 mi
Rincon del Diablo Mwd (id-1)
 28,427 0 3.7 mi
Del Dios Mutual Water Company
 330 3 5.0 mi
Olivenhain Mwd
 86,458 0 6.0 mi
Escondido, City of
Escondido		 137,044 0 6.5 mi
Carlsbad Mwd
 96,371 0 7.1 mi
Rincon del Diablo Mwd (id-A)
 5,016 0 8.2 mi
San Dieguito WD
 40,405 1 8.7 mi
Santa FE I.d.
 21,539 0 8.8 mi
Oceanside, City of
Oceanside		 174,340 0 10.2 mi
Valley Center Mwd
 30,166 0 10.3 mi
Oakvale Park
 260 3 10.4 mi
Lake Wohlford Resort
 250 0 10.4 mi
Del Mar, City of
Del Mar		 3,950 0 12.9 mi
Poway, City of
Poway		 49,888 0 12.9 mi
San Pasqual Academy
 298 0 13.2 mi
Rainbow Municipal WD
 23,536 0 14.5 mi
Rancho Pauma Mutual WC
 899 1 15.7 mi
Lazy H Mutual Water Company
 117 0 15.9 mi
Camp Pendleton (south)
 44,555 0 17.0 mi
Yuima Municipal Water District Ida
 693 0 17.0 mi
Yuima Municipal Water District
 360 0 17.0 mi
Rancho Estates Mutual Water Co.
 200 0 17.5 mi
Pauma Valley Water Company
 185 5 17.8 mi
Ramona Municipal WD
 36,455 0 17.9 mi
All 82 community water systems in San Diego County
Non-community systems in San Diego County (116: schools, campgrounds, workplaces, restaurants)

These systems serve places you visit rather than homes.

SystemServesStatusRules violated, 3 yrUnresolved
Questhaven Municipal Water District
 81 2 0
Hodges Reservoir Recreation Area
 200 0 0
Daley Ranch
 200 0 0
San Pasqual Battlefield State Park
 44 0 0
Bandy Canyon Ranch Corp
 3,564 0 0
Sycamore Canyon / Goodan Ranch
 50 0 0
Oak Knoll Village
 66 1 0
Santa Margarita County Preserve
 75 0 0
Palomar Mtn. SP Silvercrest
 143 0 0
Palomar Mtn. SP Doane Valley
 131 0 0
Yoga Center Mother's Kitchen
 101 0 0
Ramona Oaks RV Resort
 250 4 0
Rey River Ranch Corp.
 12 0 0
Fry Creek / Observatory
 660 0 0
Yoga Center Retreat
 201 0 0
Sutherland Reservoir Recreation Area
 300 1 0
Oakoasis Open Space Preserve
 25 1 0
Camp Denver Fox
 86 1 1
Fallbrook Kamp Retreat
 24 0 0
EL Monte County Park
 100 0 0
The Oaks Venture, LLC
 220 0 0
San Diego Mountain Lodge
 26,641 3 0
City of San Diego EL Capitan Reservoir
 300 0 0
Oak Grove Complex
 68 0 0
Auerbach Farms
 68 0 0
Santa Ysabel Nature Center
San Diego 		248 0 0
Mataguay Scout Reservation
 4,000 1 0
Spencer Valley School District
 40 2 0
Apple Water IS Good
 25 1 0
Calvary Chapel Julian
 101 1 0
Camp Winacka
 250 0 0
Warner Unified School District
 250 1 0
Warner Springs Ranch Resort LLC
 32 2 1
Alpine American Legion
 100 1 0
Sacred Mountain Inn
 30 1 0
Camp Cedar Glen
 65 1 0
Julian Oaks Camp
 72 0 0
Jess Martin County Park
 150 1 0
Nickel Beer Water Company
San Diego 		100 0 0
William Heise County Park
 850 1 0
Diamond Jack's RV Ranch
 115 1 1
Pinecrest
 70 0 0
Whispering Winds Catholic Conference Cen
 164 0 0
Pinezanita Inc.
 400 0 0
Cuyamaca SP Paso Picacho
 691 0 0
Skyline Ranch RV Park & Campground
 45 0 0
KQ Ranch Resort
 400 0 0
Descanso Fire Station
 34 0 0
All Saints Retreat and Formation Center
 72 2 1
Descanso Junction
 100 1 0
All non-community systems
About this data

Water systems are matched to San Diego County, nearest to San Marcos first. Your exact provider depends on your address and connection; the largest community water system in a county is usually the city or town utility. Distances are measured to the centre of the service area EPA publishes for the system.

Town locations and ZIP code areas come from U.S. Census Bureau 2020 files.

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.