Tapcensus

Water quality for ZIP code 91789

ZIP 91789 covers Walnut, Industry, Diamond Bar, Rowland Heights, Pomona, and West Covina 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

Walnut Valley Water District CA1910234 · Community water system · Surface water purchased
Serves 100,941 people Rules violated, past 3 years 0 Last sanitary survey Jun 27, 2023 Distance 1.4 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
Valencia Heights Water Co.
 7,775 0 3.0 mi
Calif State Polytechnical Univ Pomona
 2,668 2 3.3 mi
Three Valleys Mwd
 0 0 3.6 mi
Rowland Water District
 56,100 0 4.1 mi
Suburban Water Systems-San Jose
 170,523 0 4.2 mi
Suburban Water Systems-Covina Knolls
 1,451 0 4.3 mi
Covina-City, Water Dept.
Covina		 33,300 0 4.8 mi
Covina Valley Water Company Wholesale
 0 0 5.1 mi
LA Puente Valley Cwd
 8,276 0 5.4 mi
Gswc-San Dimas
 56,564 0 5.8 mi
Pomona City, Water Dept.
Pomona		 151,713 0 6.1 mi
City of Industry Waterworks Systems
La Puente		 6,151 0 6.5 mi
LA Habra Heights Cwd
 5,682 0 6.8 mi
Suburban Water Systems-Glendora
 5,301 0 7.2 mi
Azusa Light and Water
 110,044 0 7.6 mi
Glendora-City, Water Dept.
Glendora		 44,411 0 8.0 mi
Metropolitan Water Dist. of So. Cal.
 0 0 8.1 mi
Valley County Water Dist.
 68,871 0 8.1 mi
Valley View Mutual Water Co.
 4,613 0 8.5 mi
California Domestic Water Company
 0 0 9.2 mi
LA Verne, City WD
La Verne		 31,334 0 9.2 mi
Del Rio Mutual
 700 1 9.9 mi
San Gabriel Valley Water Co.-El Monte
 240,000 0 9.9 mi
Sterling Mutual Water Company
 198 2 10.0 mi
Suburban Water Systems-Whittier
 66,565 0 10.1 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
Usfs-Chantry Flats-A16 Water
 113 0 0
Henninger Flats
 50 0 0
Plant Water Well Rockview Dairy
South Gate 		45 0 0
Rancho los Amigos Hospital
 3,200 0 0
Usfs-Skyline Park / Mount Wilson A-4
 25 0 0
Coldbrook Campground
 38 0 0
Usfs-Crystal Lake B-13 Water
 2,000 0 0
Usfs-Red Box Station A-3
 25 0 0
Young-Nak Presbyterian Church
 25 0 0
Millard Canyon Improvement Association
 42 1 0
Usfs-Chilao Main A-9
 50 0 0
Angeles Crest Christian Camp
 112 1 0
Colby Ranch-United Methodist Camp
 180 0 0
Clear Creek Outdoor Education Center
 105 0 0
Huttopia Paradise Springs
 302 1 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
Usfs-Jackson Lake V-4
 805 0 0
Usfs-Appletree Flats V-3
 25 0 0
Usfs-Monte Cristo Camp T-4
 116 0 0
Camp Elk
 121 0 0
Usfs-Valyermo Ranger Station
 25 1 1
Rancho Ybarra Christian Camp
 73 0 0
Saint Andrews Abbey
 210 1 1
Angeles Shooting Ranges
 490 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
Acton la North KOA
 400 0 0
Acton Conservation Camp #11
 90 4 0
General Atomics Aeronautical Gray Butt
 405 0 0
Desert Aire Golf Course
 80 0 0
Vasquez Rocks County Park
 30 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
Los Angeles World Airports
 180 0 0
Agua Dulce Winery
 113 0 0
Living Springs Church
 50 0 0
Shepherd of the Hills
 80 0 0
Lockheed Martin Skunk Works
 135 0 0
Antelope Valley Indian Museum State Park
 506 0 0
LE Chene Restaurant Water System
 100 0 0
Northrop Grumman Corp.
 5,764 1 0
Lancaster National Soccer Center
Lancaster 		500 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.