We found 228 public water systems in San Luis Obispo county (ordered by population size).
| Name | Areas served | Population served | Contaminant count | Violation count |
|---|---|---|---|---|
| San Luis Obispo Water Department | County of San Luis Obispo | 46,117 | 60 | 1 |
| Atascadero Mutual Water Co | Atascadero | 31,536 | 90 | 1 |
| Paso Robles Water Department | Paso Robles | 31,398 | 212 | 4 |
| Arroyo Grande, Water Department | Arroyo Grande | 17,636 | 54 | 2 |
| California Mens Colony | San Luis Obispo | 15,000 | 43 | 2 |
| Grover Beach Water Department | Grover Beach | 13,505 | 83 | 3 |
| Nipomo Comm Services Dist | Nipomo | 12,886 | 111 | 4 |
| Morro Bay Pw Dept - Water Division | Morro Bay | 10,234 | 39 | 5 |
| California Mens Colony | County of San Luis Obispo | 8,900 | 0 | 0 |
| California Mens Colony | County of San Luis Obispo | 8,900 | 0 | 0 |
| Pismo Beach Water Department | County of San Luis Obispo | 8,181 | 0 | 1 |
| Oceano Comm Services Dist. | County of San Luis Obispo | 8,118 | 0 | 9 |
| Los Osos Community Services District | County of San Luis Obispo | 7,086 | 70 | 1 |
| Templeton Csd | County of San Luis Obispo | 6,883 | 0 | 1 |
| Cambria Comm Services Dist | County of San Luis Obispo | 6,032 | 0 | 6 |
| Golden State Water Company - Los Osos | County of San Luis Obispo | 5,512 | 0 | 0 |
| Golden State Water Company - Nipomo | County of San Luis Obispo | 4,397 | 0 | 0 |
| Heritage Ranch Csd | County of San Luis Obispo | 3,428 | 0 | 4 |
| Golden State Water Company-cypress Ridge | County of San Luis Obispo | 2,680 | 0 | 24 |
| Cayucos Beach Mutual Water Company | County of San Luis Obispo | 2,577 | 0 | 1 |
| Atascadero State Hospital | County of San Luis Obispo | 2,500 | 0 | 2 |
| Woodlands Development | Nipomo | 2,397 | 25 | 1 |
| San Miguel Community Services District | County of San Luis Obispo | 2,336 | 0 | 1 |
| Morro Rock Mutual Water Co | County of San Luis Obispo | 2,131 | 0 | 1 |
| Agnews Residential Facility | County of San Luis Obispo | 1,903 | 0 | 0 |
| Atascadero State Hospital | County of San Luis Obispo | 1,900 | 0 | 0 |
| Atascadero State Hopsital | County of San Luis Obispo | 1,900 | 0 | 0 |
| Nacimiento Water Company | County of San Luis Obispo | 1,820 | 0 | 19 |
| Avila Beach Community Services District | County of San Luis Obispo | 1,627 | 0 | 0 |
| Tiger Water Supply | County of San Luis Obispo | 1,600 | 0 | 2 |
| San Miguelito Mwc | County of San Luis Obispo | 1,395 | 0 | 2 |
| Slo Csa No. 16 - Shandon | County of San Luis Obispo | 1,295 | 0 | 0 |
| Golden State Water Company - Edna | County of San Luis Obispo | 1,294 | 0 | 1 |
| Slo Cwwd No. 23 - Santa Margarita | County of San Luis Obispo | 1,259 | 0 | 1 |
| Pg&e | County of San Luis Obispo | 1,200 | 0 | 26 |
| County Of Monterey-lake Nacimiento | County of San Luis Obispo | 1,000 | 0 | 5 |
| Montana De Oro State Park | County of San Luis Obispo | 990 | 0 | 2 |
| Slocsa #10a - Cayucos | County of San Luis Obispo | 857 | 0 | 0 |
| Caltrans - Shandon Rest Stop | County of San Luis Obispo | 800 | 0 | 4 |
| Mesa Dunes Mobile Home Estates | County of San Luis Obispo | 800 | 0 | 4 |
| Madonna Inn Water Company | County of San Luis Obispo | 650 | 0 | 4 |
| S & T Mutual Water Company | County of San Luis Obispo | 575 | 0 | 3 |
| Branch Elementary School | County of San Luis Obispo | 500 | 0 | 0 |
| Woodland Park Mutual Water Co | County of San Luis Obispo | 500 | 0 | 5 |
| Hearst Memorial State Beach | County of San Luis Obispo | 500 | 0 | 1 |
| Dana Elementary School | County of San Luis Obispo | 500 | 0 | 0 |
| Walnut Hills Mutual Water Co | County of San Luis Obispo | 486 | 0 | 4 |
| San Simeon Csd | County of San Luis Obispo | 462 | 0 | 2 |
| Los Robles Mobile Home Estates | County of San Luis Obispo | 420 | 0 | 4 |
| Vines R.v. Resort | County of San Luis Obispo | 400 | 0 | 0 |
| Laureate Water Company | County of San Luis Obispo | 350 | 0 | 3 |
| Green River Mutual Water Co. | County of San Luis Obispo | 350 | 0 | 8 |
| Ernie Ball, Inc | County of San Luis Obispo | 300 | 0 | 0 |
| Rancho Colina Mobile Home Park | County of San Luis Obispo | 250 | 0 | 3 |
| Fiero Lane Water Company, Inc. | County of San Luis Obispo | 250 | 0 | 2 |
| Garden Farms C.w.d. | County of San Luis Obispo | 240 | 0 | 6 |
| Sycamore Mineral Springs Resort | County of San Luis Obispo | 200 | 0 | 3 |
| Bella Vista Mobile Lodge | County of San Luis Obispo | 200 | 0 | 0 |
| Strasbaugh, Inc | County of San Luis Obispo | 200 | 0 | 0 |
| Hearst Monument State Park | County of San Luis Obispo | 200 | 0 | 5 |
| Cal Shasta Club | County of San Luis Obispo | 166 | 0 | 3 |
| Vachell Water System | County of San Luis Obispo | 150 | 0 | 1 |
| Coast Union High School | County of San Luis Obispo | 150 | 0 | 0 |
| Phillips 66 Company, Santa Maria Facilit | County of San Luis Obispo | 140 | 0 | 0 |
| Irish Hills Mutual Water Co | County of San Luis Obispo | 135 | 0 | 4 |
| Canyon Crest Mutual Benefit Wc | County of San Luis Obispo | 125 | 0 | 1 |
| Varian Ranch Mutual Water | County of San Luis Obispo | 120 | 0 | 0 |
| Halcyon Water System | County of San Luis Obispo | 105 | 0 | 0 |
| Paso Robles Rv Ranch | County of San Luis Obispo | 105 | 0 | 0 |
| Pleasant Valley Elementary | County of San Luis Obispo | 100 | 0 | 0 |
| Clearwater Nursery | County of San Luis Obispo | 100 | 0 | 0 |
| San Luis Business Park | County of San Luis Obispo | 100 | 0 | 0 |
| Ragged Point Inn | County of San Luis Obispo | 100 | 0 | 0 |
| Lopez Recreation Area | County of San Luis Obispo | 100 | 0 | 0 |
| Christmas Cove | County of San Luis Obispo | 100 | 0 | 0 |
| Santa Margarita Recreation Area | County of San Luis Obispo | 100 | 0 | 0 |
| Creston Elementary School | County of San Luis Obispo | 100 | 0 | 0 |
| Noll Properties | County of San Luis Obispo | 100 | 0 | 0 |
| Santa Maria Speedway | County of San Luis Obispo | 100 | 0 | 0 |
| Port San Luis Harbor District | County of San Luis Obispo | 100 | 0 | 0 |
| Satcom Water Supply--camp Roberts | County of San Luis Obispo | 100 | 0 | 0 |
| Las Ventanas Ranch | County of San Luis Obispo | 100 | 0 | 0 |
| Morro Bay Mutual Water Co | County of San Luis Obispo | 100 | 0 | 0 |
| Tri Counties Club | County of San Luis Obispo | 87 | 0 | 0 |
| Bassi Ranch Mutual Water Co. | County of San Luis Obispo | 85 | 0 | 0 |
| Ken Mar Gardens | County of San Luis Obispo | 84 | 0 | 0 |
| Laguna Negra Mutual Water Co. | County of San Luis Obispo | 80 | 0 | 0 |
| Keep Ocean | County of San Luis Obispo | 80 | 0 | 0 |
| Whitson Industrial Park | County of San Luis Obispo | 75 | 0 | 0 |
| Resthaven Mobile Home Park | County of San Luis Obispo | 75 | 0 | 0 |
| Talley Farms Labor Housing | County of San Luis Obispo | 75 | 0 | 0 |
| Afuera De Chorro Water Company | County of San Luis Obispo | 75 | 0 | 0 |
| Creekside Commercial Center | County of San Luis Obispo | 75 | 0 | 0 |
| Ball Tagawa Growers | County of San Luis Obispo | 70 | 0 | 0 |
| Carrisa Plains Elementary | County of San Luis Obispo | 65 | 0 | 0 |
| Rancho Nipomo Water Company | County of San Luis Obispo | 65 | 0 | 0 |
| Avila Valley Mutual Water Co | County of San Luis Obispo | 65 | 0 | 0 |
| Edna Valley Ranch East | County of San Luis Obispo | 60 | 0 | 0 |
| Monte Sereno Mutual Benefit Water | County of San Luis Obispo | 60 | 0 | 0 |
| Country Hills Estates | County of San Luis Obispo | 60 | 0 | 0 |
| H2o, Inc | County of San Luis Obispo | 60 | 0 | 0 |
| San Luis Sourdough - Inactive | County of San Luis Obispo | 60 | 0 | 0 |
| Hidden Hills Mobilodge | County of San Luis Obispo | 55 | 0 | 0 |
| Rim Rock Water Company | County of San Luis Obispo | 55 | 0 | 0 |
| Grande Mobile Manor | County of San Luis Obispo | 55 | 0 | 0 |
| Santa Lucia School | County of San Luis Obispo | 52 | 0 | 0 |
| Greenheart Farms | County of San Luis Obispo | 50 | 0 | 0 |
| Skyline Flower Growers & Shippers | County of San Luis Obispo | 50 | 0 | 0 |
| Babe Ruth's Oak View | County of San Luis Obispo | 50 | 0 | 0 |
| Northshore S & B, Inc | County of San Luis Obispo | 50 | 0 | 0 |
| Laguna Vista Boat Club | County of San Luis Obispo | 50 | 0 | 0 |
| Santa Margarita Koa | County of San Luis Obispo | 50 | 0 | 0 |
| Hunter Ranch Golf Course | County of San Luis Obispo | 50 | 0 | 0 |
| Rancho Salinas Mbwc | County of San Luis Obispo | 50 | 0 | 0 |
| East Airport Fiero Lane Water Company | County of San Luis Obispo | 50 | 0 | 0 |
| Kukkula Inc | County of San Luis Obispo | 50 | 0 | 0 |
| House Of Prayer | County of San Luis Obispo | 50 | 0 | 0 |
| Copeland's Distribution Center | County of San Luis Obispo | 50 | 0 | 0 |
| Bear Valley Water Company | San Luis Obispo | 45 | 0 | 0 |
| Horizon Lane Water Supply | County of San Luis Obispo | 45 | 0 | 0 |
| Tank Farm Business Park | County of San Luis Obispo | 45 | 0 | 0 |
| Trumpet Vine Catering | County of San Luis Obispo | 45 | 0 | 0 |
| Brookside Tract | County of San Luis Obispo | 44 | 0 | 0 |
| Double J Mobile Estates | County of San Luis Obispo | 43 | 0 | 0 |
| San Simeon Creek Ranch | County of San Luis Obispo | 42 | 0 | 0 |
| First Baptist Church | County of San Luis Obispo | 40 | 0 | 0 |
| Slo Partners | County of San Luis Obispo | 40 | 0 | 0 |
| Paragon Triangle Water Supply | County of San Luis Obispo | 40 | 0 | 0 |
| Almira Water Association | County of San Luis Obispo | 40 | 0 | 0 |
| Spanish Lakes Mutual Water Co | County of San Luis Obispo | 40 | 0 | 0 |
| Pacific Dunes Ranch | County of San Luis Obispo | 40 | 0 | 0 |
| Elks Lodge #322 | County of San Luis Obispo | 40 | 0 | 0 |
| Toyota San Luis Obispo | County of San Luis Obispo | 35 | 0 | 0 |
| Tank Farm Industrial Plaza | County of San Luis Obispo | 35 | 0 | 0 |
| Ups - San Luis Obispo | County of San Luis Obispo | 35 | 0 | 0 |
| Black Mountain R.v. Resort | County of San Luis Obispo | 35 | 0 | 0 |
| Terra De Oro Water Company | County of San Luis Obispo | 35 | 0 | 0 |
| Arroyo Grande Mushroom Farm | County of San Luis Obispo | 35 | 0 | 0 |
| Speedling, Inc | County of San Luis Obispo | 35 | 0 | 0 |
| Guadalupe Cooling Company | County of San Luis Obispo | 35 | 0 | 0 |
| Goodwill Industries | County of San Luis Obispo | 35 | 0 | 0 |
| Cb & I Constructors, Inc. | County of San Luis Obispo | 35 | 0 | 0 |
| Chevron | County of San Luis Obispo | 35 | 0 | 0 |
| Wallace Water Systems | County of San Luis Obispo | 35 | 0 | 0 |
| Mustang Mobile Village | County of San Luis Obispo | 31 | 0 | 0 |
| Callender Grove Mutual Water | County of San Luis Obispo | 30 | 0 | 0 |
| Mustang Springs Mutual Water | County of San Luis Obispo | 30 | 0 | 0 |
| Holdgrafer & Associates | County of San Luis Obispo | 30 | 0 | 0 |
| Cerro Alto Campground | County of San Luis Obispo | 30 | 0 | 0 |
| Higuera Apartments | County of San Luis Obispo | 30 | 0 | 0 |
| Mutual Water Association | County of San Luis Obispo | 30 | 0 | 0 |
| Jack Ranch Cafe | County of San Luis Obispo | 30 | 0 | 0 |
| Longbranch Saloon, The | County of San Luis Obispo | 30 | 0 | 0 |
| Parsons Water Supply | County of San Luis Obispo | 30 | 0 | 0 |
| Paso 360 | County of San Luis Obispo | 30 | 0 | 0 |
| Williams Water Co | County of San Luis Obispo | 30 | 0 | 0 |
| Crossroads/ House Of Prayer | County of San Luis Obispo | 30 | 0 | 0 |
| California Valley Community Se | County of San Luis Obispo | 30 | 0 | 0 |
| Slo County Farm Bureau | County of San Luis Obispo | 30 | 0 | 0 |
| Broken Earth Winery | County of San Luis Obispo | 28 | 0 | 0 |
| J M Sims Water Supply | County of San Luis Obispo | 27 | 0 | 0 |
| Copeland's Properties | County of San Luis Obispo | 25 | 0 | 0 |
| Cuyama Lane Water Company | County of San Luis Obispo | 25 | 0 | 0 |
| San Paso Truck Stop | County of San Luis Obispo | 25 | 0 | 0 |
| Congregation Beth David | County of San Luis Obispo | 25 | 0 | 0 |
| Creston Country Store | County of San Luis Obispo | 25 | 0 | 0 |
| Baron Canyon Mutual Water Co. | County of San Luis Obispo | 25 | 0 | 0 |
| Links At Vista Del Hombre, The | County of San Luis Obispo | 25 | 0 | 0 |
| Laetitia Vineyard & Winery Inc | County of San Luis Obispo | 25 | 0 | 0 |
| 200 Suburban Road Water Supply | County of San Luis Obispo | 25 | 0 | 0 |
| 141 Suburban Road Water Supply | County of San Luis Obispo | 25 | 0 | 0 |
| Biddle Regional County Park | County of San Luis Obispo | 25 | 0 | 0 |
| Paso Robles Chevrolet Cadillac | County of San Luis Obispo | 25 | 0 | 0 |
| Pozo Saloon | County of San Luis Obispo | 25 | 0 | 0 |
| Granite Ridge | County of San Luis Obispo | 25 | 0 | 0 |
| Sunset Drive-in Snack Bar | County of San Luis Obispo | 25 | 0 | 0 |
| Loading Chute | County of San Luis Obispo | 25 | 0 | 0 |
| Santa Ysabel Ranch Mwc | County of San Luis Obispo | 25 | 0 | 0 |
| Rinconada Trailer Park | County of San Luis Obispo | 25 | 0 | 0 |
| Garl, Keith | County of San Luis Obispo | 25 | 0 | 0 |
| Niner Wine Estates, Llc | County of San Luis Obispo | 25 | 0 | 0 |
| Edna Valley Vineyards | County of San Luis Obispo | 25 | 0 | 0 |
| Aronhill Vineyard | County of San Luis Obispo | 25 | 0 | 0 |
| Inn At Opolo Kitchen, The | County of San Luis Obispo | 25 | 0 | 0 |
| Daou Vineyards, Llc | County of San Luis Obispo | 25 | 0 | 0 |
| Last Stage West | County of San Luis Obispo | 25 | 0 | 0 |
| Atascadero Lake - Inactive | County of San Luis Obispo | 25 | 0 | 0 |
| Redwood Payless Station | County of San Luis Obispo | 25 | 0 | 0 |
| Hazard Water Supply | County of San Luis Obispo | 25 | 0 | 0 |
| Suburban Lodge | County of San Luis Obispo | 25 | 0 | 0 |
| Ramona Motel | County of San Luis Obispo | 25 | 0 | 0 |
| Richard Nock, Pres | County of San Luis Obispo | 25 | 0 | 0 |
| Hermreck Shopping Center | County of San Luis Obispo | 25 | 0 | 0 |
| Oak Park Manor | County of San Luis Obispo | 25 | 0 | 0 |
| Rancho El Chorro School | County of San Luis Obispo | 25 | 0 | 0 |
| Gerald E Brewster - Inactive | County of San Luis Obispo | 25 | 0 | 0 |
| Rifle Fairing Water Supply | County of San Luis Obispo | 25 | 0 | 0 |
| Harmony Water Works | County of San Luis Obispo | 25 | 0 | 0 |
| Parks & Recreation | County of San Luis Obispo | 25 | 0 | 0 |
| Piedras Blancas Water Supply | County of San Luis Obispo | 25 | 0 | 0 |
| Ray W Shamel Park | County of San Luis Obispo | 25 | 0 | 0 |
| San Luis Obispo | County of San Luis Obispo | 25 | 0 | 0 |
| Union Properties | County of San Luis Obispo | 25 | 0 | 0 |
| Buttonwood Industrial Park | County of San Luis Obispo | 25 | 0 | 0 |
| Hedger Water Supply - Inactive | County of San Luis Obispo | 25 | 0 | 0 |
| Lopez Trout Farm - Inactive | County of San Luis Obispo | 25 | 0 | 0 |
| Design Alliance - Inactive | County of San Luis Obispo | 25 | 0 | 0 |
| 7x Youth Ranch | County of San Luis Obispo | 25 | 0 | 0 |
| Vista De Las Flores Water | County of San Luis Obispo | 24 | 0 | 0 |
| Nunes Water Company | County of San Luis Obispo | 24 | 0 | 0 |
| Mesa Mutual Water Company | County of San Luis Obispo | 24 | 0 | 0 |
| San Luis Water & Power | County of San Luis Obispo | 24 | 0 | 0 |
| Sweet Springs Mobile Park | County of San Luis Obispo | 24 | 0 | 0 |
| Newsom Springs Mutual Water Co | County of San Luis Obispo | 24 | 0 | 0 |
| Maxwellton Mutual Water | County of San Luis Obispo | 24 | 0 | 0 |
| Blue Sky Water Association | County of San Luis Obispo | 24 | 0 | 0 |
| Estrella Correctional Facility | County of San Luis Obispo | 20 | 0 | 0 |
| Rancho Oaks Mobile Park | County of San Luis Obispo | 19 | 0 | 0 |
| Victorian Manor Water Supply | County of San Luis Obispo | 10 | 0 | 0 |
| Csp San Simeon Creek St Beach | County of San Luis Obispo | 8 | 0 | 0 |
| Embers Cafe | County of San Luis Obispo | 4 | 0 | 0 |
| Union Oil Company - Santa Mari | County of San Luis Obispo | 1 | 0 | 0 |
| Slo Cwd No. 10 - Cayucos Wtp | County of San Luis Obispo | 0 | 0 | 0 |
| Nacimiento Water Project | County of San Luis Obispo | 0 | 0 | 0 |
| Lopez Project | County of San Luis Obispo | 0 | 0 | 0 |
| San Luis Obispo Csa 1g- Black Lake | Black Lake | 0 | 0 | 0 |
| Slo Csa No. 12 - Avila Beach | County of San Luis Obispo | 0 | 0 | 0 |
| Avila Beach County Water Dist | County of San Luis Obispo | 0 | 0 | 0 |