Tapcensus

Water quality for ZIP code 91768

ZIP 91768 covers Pomona and Diamond Bar in Los Angeles County, California, one of 295 ZIP codes in the county. 271 active public water systems serve the county; 66 had an EPA violation in the past three years.

Most likely your provider

Gswc-San Dimas CA1910142 · Community water system · Surface water purchased
Serves 56,564 people Rules violated, past 3 years 0 Last sanitary survey May 8, 2025 Distance 3.0 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 Los Angeles County

198 systems, nearest first
SystemServesStatusRules violated, 3 yrDistance
Three Valleys Mwd
 0 0 1.5 mi
Pomona City, Water Dept.
Pomona		 151,713 0 1.8 mi
Calif State Polytechnical Univ Pomona
 2,668 2 1.8 mi
Suburban Water Systems-Covina Knolls
 1,451 0 3.8 mi
Metropolitan Water Dist. of So. Cal.
 0 0 4.0 mi
Covina Valley Water Company Wholesale
 0 0 4.2 mi
Valencia Heights Water Co.
 7,775 0 4.4 mi
Walnut Valley Water District
 100,941 0 4.6 mi
LA Verne, City WD
La Verne		 31,334 0 4.7 mi
Covina-City, Water Dept.
Covina		 33,300 0 5.3 mi
Gswc Claremont
 39,776 0 5.5 mi
Glendora-City, Water Dept.
Glendora		 44,411 0 6.0 mi
Suburban Water Systems-Glendora
 5,301 0 6.3 mi
Suburban Water Systems-San Jose
 170,523 0 7.8 mi
Azusa Light and Water
 110,044 0 7.9 mi
Rowland Water District
 56,100 0 8.9 mi
LA Puente Valley Cwd
 8,276 0 9.6 mi
Valley County Water Dist.
 68,871 0 9.9 mi
City of Industry Waterworks Systems
La Puente		 6,151 0 10.4 mi
Valley View Mutual Water Co.
 4,613 0 10.9 mi
Cal-Am Water Company Duarte
 24,767 0 11.1 mi
Camp Williams-Resort Water
 80 0 11.7 mi
LA Habra Heights Cwd
 5,682 0 11.7 mi
The River Community
 35 2 11.7 mi
Hemlock Mutual Water Co.
 686 2 12.5 mi
All 199 community water systems in Los Angeles County
Non-community systems in Los Angeles County (72: schools, campgrounds, workplaces, restaurants)

These systems serve places you visit rather than homes.

SystemServesStatusRules violated, 3 yrUnresolved
Irwindale Brewery Yard (iby)
 300 0 0
Martin Marietta Southern Calif Aggregate
 51 0 0
Coldbrook Campground
 38 0 0
Usfs-Chantry Flats-A16 Water
 113 0 0
Usfs-Crystal Lake B-13 Water
 2,000 0 0
Usfs-Skyline Park / Mount Wilson A-4
 25 0 0
Henninger Flats
 50 0 0
Usfs-Chilao Main A-9
 50 0 0
Usfs-Red Box Station A-3
 25 0 0
Mount Kare Camp/kare Youth League
 59 0 0
Usfs-Big Pines V-2
 54 0 0
Mountain High East Ski Area
 150 0 0
Angeles Crest Christian Camp
 112 1 0
Plant Water Well Rockview Dairy
South Gate 		45 0 0
Usfs-Jackson Lake V-4
 805 0 0
Millard Canyon Improvement Association
 42 1 0
Usfs-Appletree Flats V-3
 25 0 0
Huttopia Paradise Springs
 302 1 0
Rancho los Amigos Hospital
 3,200 0 0
Camp Elk
 121 0 0
Colby Ranch-United Methodist Camp
 180 0 0
Young-Nak Presbyterian Church
 25 0 0
Clear Creek Outdoor Education Center
 105 0 0
Usfs-Valyermo Ranger Station
 25 1 1
Usfs-Monte Cristo Camp T-4
 116 0 0
Saint Andrews Abbey
 210 1 1
Rancho Ybarra Christian Camp
 73 0 0
General Atomics Aeronautical Gray Butt
 405 0 0
1000 Trails / Soledad Canyon Preserve
 812 1 0
Acton Four Square Church
 50 0 0
Acton-Agua Dulce Lds Church
 150 0 0
Angeles Shooting Ranges
 490 0 0
Acton la North KOA
 400 0 0
Acton Conservation Camp #11
 90 4 0
Desert Aire Golf Course
 80 0 0
Antelope Valley Indian Museum State Park
 506 0 0
Los Angeles World Airports
 180 0 0
Vasquez Rocks County Park
 30 0 0
Lockheed Martin Skunk Works
 135 0 0
Ilead Agua Dulce Charter School
 450 1 1
Agua Dulce Women's Club
 50 0 0
Lang Ranch Shopping Center
 28 0 0
Wagon Wheel Plaza
 55 1 0
Agua Dulce Water System
 493 0 0
Northrop Grumman Corp.
 5,764 1 0
Agua Dulce Winery
 113 0 0
Living Springs Church
 50 0 0
Shepherd of the Hills
 80 0 0
Lancaster National Soccer Center
Lancaster 		500 0 0
LE Chene Restaurant Water System
 100 0 0
All non-community systems
About this data

Water systems are matched to Los Angeles County, the county this ZIP code lies in, nearest to the ZIP code's centre 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.

ZIP code areas and town boundaries come from the U.S. Census Bureau's 2020 ZCTA 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.