We found 176 public water systems in Contra Costa county (ordered by population size).
| Name | Areas served | Population served | Contaminant count | Violation count |
|---|---|---|---|---|
| Contra Costa Water District | County of Contra Costa | 198,000 | 61 | 2 |
| City Of Antioch | Antioch | 103,833 | 39 | 3 |
| City Of Pittsburg | Pittsburg | 62,500 | 36 | 2 |
| Brentwood | Brentwood | 54,700 | 226 | 20 |
| Diablo Water District | Oakley | 36,014 | 50 | 0 |
| City Of Martinez | Martinez | 35,375 | 43 | 2 |
| Golden State Water Company - Bay Point | Pittsburg | 22,258 | 64 | 2 |
| Town Of Discovery Bay | Byron | 13,500 | 27 | 3 |
| Excelsior Middle School | County of Contra Costa | 800 | 0 | 2 |
| East Bay Regional Park Dist | County of Contra Costa | 800 | 0 | 0 |
| Magalia County Water District | County of Contra Costa | 750 | 0 | 0 |
| Mount Diablo State Park | County of Contra Costa | 687 | 0 | 4 |
| Golden Eagle Small Water System | County of Contra Costa | 600 | 0 | 6 |
| Gaylord Container Company | County of Contra Costa | 600 | 0 | 0 |
| Morrell Property Mgt | County of Contra Costa | 600 | 0 | 0 |
| Lundborg Landing *cl 2/09 | County of Contra Costa | 420 | 0 | 0 |
| Santiago Island Village | County of Contra Costa | 400 | 0 | 5 |
| Pleasantimes Mutual Water Co | County of Contra Costa | 380 | 0 | 6 |
| Willow Park Marina | County of Contra Costa | 380 | 0 | 0 |
| Willow Mobile Home Park | County of Contra Costa | 350 | 0 | 6 |
| Orwood Resort | County of Contra Costa | 350 | 0 | 4 |
| Knightsen Elementary School | County of Contra Costa | 350 | 0 | 22 |
| Ben Kutch | County of Contra Costa | 345 | 0 | 0 |
| Orin Allen Youth Rehab Facility | County of Contra Costa | 300 | 0 | 14 |
| Jehovahs Witnesse Church *cl 2/13 | County of Contra Costa | 300 | 0 | 0 |
| Clayton Palms Water | County of Contra Costa | 287 | 0 | 5 |
| Knightsen Community Water System | County of Contra Costa | 250 | 0 | 0 |
| Neighborhood Church | County of Contra Costa | 250 | 0 | 4 |
| Lighthouse Baptist Church | County of Contra Costa | 250 | 0 | 0 |
| Riverview Water Association | County of Contra Costa | 230 | 0 | 9 |
| Delta Mutual Water Company | County of Contra Costa | 225 | 0 | 4 |
| Riverview Mobile Homes | County of Contra Costa | 216 | 0 | 5 |
| Camino Mobilehome | County of Contra Costa | 210 | 0 | 9 |
| Anglers Subdivision 4 | County of Contra Costa | 210 | 0 | 7 |
| Canyon School | County of Contra Costa | 200 | 0 | 15 |
| Flamingo Mobile Manor | County of Contra Costa | 200 | 0 | 12 |
| Genos Deli Station | County of Contra Costa | 200 | 0 | 11 |
| Church Of Jesus Christ | County of Contra Costa | 200 | 0 | 0 |
| Blazing Saddle Bar & Grill | County of Contra Costa | 200 | 0 | 0 |
| Csp Benicia State Park | Nc Park Res | 191 | 0 | 0 |
| Franks Marina | County of Contra Costa | 185 | 0 | 5 |
| Dwr Delta Field Division - Banks Pp | County of Contra Costa | 180 | 0 | 2 |
| Oakley Mutual Water Company | County of Contra Costa | 170 | 0 | 2 |
| Sandmound Mutual | County of Contra Costa | 160 | 0 | 5 |
| Joe Brown, Manager | County of Contra Costa | 160 | 0 | 0 |
| Big Oak Mobile Home Park Water | County of Contra Costa | 156 | 0 | 9 |
| Sugar Barge Marina | County of Contra Costa | 150 | 0 | 1 |
| Lazy M Marina | County of Contra Costa | 150 | 0 | 8 |
| Delta Sportsman | County of Contra Costa | 150 | 0 | 12 |
| Bruns Memorial Amphitheater | County of Contra Costa | 150 | 0 | 0 |
| Lia Hona Club L.d.s. | County of Contra Costa | 150 | 0 | 0 |
| Bethel Island Mutual Water Co | County of Contra Costa | 149 | 0 | 5 |
| Farrar Park Property Owners | County of Contra Costa | 140 | 0 | 4 |
| Willow Pass Mobile Home *cl 1/07-inactiv | County of Contra Costa | 140 | 0 | 0 |
| Laborers Training And Retraini | County of Contra Costa | 125 | 0 | 0 |
| Gas N Save | County of Contra Costa | 120 | 0 | 0 |
| Concord Mt Diablo Trailride Assoc. | County of Contra Costa | 120 | 0 | 0 |
| Russos Mobile Park | County of Contra Costa | 110 | 0 | 0 |
| Northgate Mutual Water | County of Contra Costa | 105 | 0 | 0 |
| Bethel Market | County of Contra Costa | 100 | 0 | 0 |
| Joes Island Restaurant | County of Contra Costa | 100 | 0 | 0 |
| Los Vaqueros Interpretive Center | County of Contra Costa | 100 | 0 | 0 |
| Farmers Daughter Water Sys *closed* | County of Contra Costa | 100 | 0 | 0 |
| Oroville-wyandotte Irrig Dist | County of Contra Costa | 100 | 0 | 0 |
| Dwr Delta Field Division-banks Pump | Copperopolis | 100 | 0 | 0 |
| Holy Cross Cemetery *cl 2/28/15 | County of Contra Costa | 100 | 0 | 0 |
| Sandy Point Mobile Home Park | County of Contra Costa | 94 | 0 | 0 |
| Bella Vista Water Sys | County of Contra Costa | 93 | 0 | 0 |
| Byron Corners Inc | County of Contra Costa | 90 | 0 | 0 |
| Bethel Missionary Baptist | County of Contra Costa | 90 | 0 | 0 |
| Wilcox Station Ranch | County of Contra Costa | 90 | 0 | 0 |
| Macs Old House | County of Contra Costa | 90 | 0 | 0 |
| Wildwood Acres Resort | County of Contra Costa | 90 | 0 | 0 |
| North American Refractories - Inactive | County of Contra Costa | 90 | 0 | 0 |
| Bethel Island Golf Course & Country Club | County of Contra Costa | 80 | 0 | 0 |
| Bridgehead Cafe | County of Contra Costa | 80 | 0 | 0 |
| New Life Marina | County of Contra Costa | 80 | 0 | 0 |
| Ronald Nunn | County of Contra Costa | 80 | 0 | 0 |
| Bethel Baptist Church | County of Contra Costa | 75 | 0 | 0 |
| Old Borges Ranch Water Sys | County of Contra Costa | 75 | 0 | 0 |
| Marina Mobile Manor | County of Contra Costa | 75 | 0 | 0 |
| Golf Club At Roddy Ranch | County of Contra Costa | 75 | 0 | 0 |
| Cruiser Haven Marina | County of Contra Costa | 75 | 0 | 0 |
| Launderette Water System *cl 04 | County of Contra Costa | 75 | 0 | 0 |
| Tugs | County of Contra Costa | 70 | 0 | 0 |
| Ebrpd Alhambra | County of Contra Costa | 70 | 0 | 0 |
| Rayners Grocery Sws **closed** | County of Contra Costa | 70 | 0 | 0 |
| Wahl Family Water System | County of Contra Costa | 65 | 0 | 0 |
| Ebrpd Round Valley Water System | County of Contra Costa | 65 | 0 | 0 |
| Davis Camp *cl 10/08 | County of Contra Costa | 65 | 0 | 0 |
| Bonnie & Clydes Saloon | County of Contra Costa | 65 | 0 | 0 |
| Moraga Heights Mutual Water | County of Contra Costa | 60 | 0 | 0 |
| Bon Gustos | County of Contra Costa | 60 | 0 | 0 |
| Byron Inn | County of Contra Costa | 60 | 0 | 0 |
| Angler S Ranch #3 | County of Contra Costa | 60 | 0 | 0 |
| Thomas Denova Llc Water System | County of Contra Costa | 60 | 0 | 0 |
| Littorno & Panfili Water System | County of Contra Costa | 60 | 0 | 0 |
| Mcavoy Yacht Harbor | County of Contra Costa | 55 | 0 | 0 |
| Csp California State Parks | County of Contra Costa | 54 | 0 | 0 |
| Byron United Methodist | County of Contra Costa | 50 | 0 | 0 |
| Los Vaqueros Marina Bldg | County of Contra Costa | 50 | 0 | 0 |
| Ebrpd Little Hills | County of Contra Costa | 50 | 0 | 0 |
| Milan E Ward | County of Contra Costa | 50 | 0 | 0 |
| Dutch Slough Water Works | County of Contra Costa | 49 | 0 | 0 |
| Doubletree Ranch Water System | County of Contra Costa | 49 | 0 | 0 |
| Brentwood Creek Farm | County of Contra Costa | 45 | 0 | 0 |
| Casa Medanos Water System | County of Contra Costa | 45 | 0 | 0 |
| Ebrpd Black Diamond Mines | County of Contra Costa | 45 | 0 | 0 |
| Beacon West | County of Contra Costa | 45 | 0 | 0 |
| Bethel Harbor | County of Contra Costa | 45 | 0 | 0 |
| Lone Tree Medical & Dental | County of Contra Costa | 45 | 0 | 0 |
| Holland Riverside Marina | County of Contra Costa | 45 | 0 | 0 |
| Marine Emporium Richards Yacht | County of Contra Costa | 45 | 0 | 0 |
| Delta Kids Center *cl 2/07 | County of Contra Costa | 45 | 0 | 0 |
| Blackwood & Ely | County of Contra Costa | 40 | 0 | 0 |
| Honolulu Grill *cl 10/07 | County of Contra Costa | 40 | 0 | 0 |
| Ebrpd Old Briones Regional Park | County of Contra Costa | 40 | 0 | 0 |
| Park Marina *cl 10/29/15 | County of Contra Costa | 35 | 0 | 0 |
| Cecchini Water | County of Contra Costa | 35 | 0 | 0 |
| Anchor Marina | County of Contra Costa | 35 | 0 | 0 |
| Byron Airport | County of Contra Costa | 35 | 0 | 0 |
| Hertz Water System | County of Contra Costa | 35 | 0 | 0 |
| New Docs Marina | County of Contra Costa | 35 | 0 | 0 |
| Bay Standards | County of Contra Costa | 35 | 0 | 0 |
| Carson Swim School | County of Contra Costa | 35 | 0 | 0 |
| Ebrpd Bear Creek Water System | County of Contra Costa | 35 | 0 | 0 |
| Blackhawk Water Service | County of Contra Costa | 33 | 0 | 0 |
| Colonia Santa Maria | County of Contra Costa | 32 | 0 | 0 |
| Sues Swim School | County of Contra Costa | 30 | 0 | 0 |
| D Anna Yacht Center *cl 2005 | County of Contra Costa | 30 | 0 | 0 |
| Willowest Marina Ws | County of Contra Costa | 30 | 0 | 0 |
| Sunset Harbor | County of Contra Costa | 30 | 0 | 0 |
| All Star Academy Of Danville | County of Contra Costa | 30 | 0 | 0 |
| Last Resort & Marina Llc | County of Contra Costa | 30 | 0 | 0 |
| Casa Del Rio Water System | County of Contra Costa | 30 | 0 | 0 |
| Lindquist Landing Marina | County of Contra Costa | 30 | 0 | 0 |
| Riverview Motel *cl 2007 | County of Contra Costa | 30 | 0 | 0 |
| Bollinger Canyon | County of Contra Costa | 30 | 0 | 0 |
| Beth Blasey | County of Contra Costa | 30 | 0 | 0 |
| 099 152 022 Pg&e Los Medanos | County of Contra Costa | 28 | 0 | 0 |
| Frank & Carole Karaglanis | County of Contra Costa | 28 | 0 | 0 |
| 010 050 003 | County of Contra Costa | 26 | 0 | 0 |
| Marin Food Specialties | County of Contra Costa | 25 | 0 | 0 |
| Ebrpd Morgan Territory | County of Contra Costa | 25 | 0 | 0 |
| Brentwood Missionary Baptist | County of Contra Costa | 25 | 0 | 0 |
| Csp Lake Oroville-spillway | Nc Spillway Lau | 25 | 0 | 0 |
| Seymour Paul Proctor | County of Contra Costa | 25 | 0 | 0 |
| James A Mcgrath | County of Contra Costa | 25 | 0 | 0 |
| Savers Sws | County of Contra Costa | 25 | 0 | 0 |
| Dudley Young | County of Contra Costa | 25 | 0 | 0 |
| Smith & Hager Water System | County of Contra Costa | 25 | 0 | 0 |
| Mt View Food Center | County of Contra Costa | 25 | 0 | 0 |
| Gary Larsen | County of Contra Costa | 25 | 0 | 0 |
| Mt Diablo State Park | County of Contra Costa | 25 | 0 | 0 |
| Boundary Oaks Tennis Corp | County of Contra Costa | 25 | 0 | 0 |
| Evergreen Mobilehome Park | County of Contra Costa | 25 | 0 | 0 |
| Mass Pheasant Club | County of Contra Costa | 25 | 0 | 0 |
| Motorcycle Recreation | County of Contra Costa | 25 | 0 | 0 |
| Valley Orchard Mutual Water System | County of Contra Costa | 24 | 0 | 0 |
| Blue Tip Trailer Park Water | County of Contra Costa | 24 | 0 | 0 |
| Castlerock Water Sys | County of Contra Costa | 22 | 0 | 0 |
| Louis & Lupe Madrigal | County of Contra Costa | 20 | 0 | 0 |
| Riverview Marina Sws | County of Contra Costa | 20 | 0 | 0 |
| Villa De Guadalupe | County of Contra Costa | 20 | 0 | 0 |
| Corner Club | County of Contra Costa | 15 | 0 | 0 |
| Leema Road Water System | County of Contra Costa | 15 | 0 | 0 |
| Baldocchi Water System | County of Contra Costa | 10 | 0 | 0 |
| Morrison Ranch | County of Contra Costa | 10 | 0 | 0 |
| Canyon Water Brothers | County of Contra Costa | 5 | 0 | 0 |
| Nagle Apartments | County of Contra Costa | 4 | 0 | 0 |
| YOSEMITE WEST | County of Contra Costa | 3 | 0 | 0 |
| Ccwd/brentwood Wtp | County of Contra Costa | 1 | 0 | 0 |
| Randall-bold Water Treatment Plant | County of Contra Costa | 1 | 0 | 0 |
| Blue Goose Property | County of Contra Costa | 1 | 0 | 0 |
| Mark & Deborah Reisbeck | County of Contra Costa | 0 | 0 | 0 |
| Owid-community Line | Community Line | 0 | 0 | 0 |