Tapcensus

Water quality for ZIP code 91001

ZIP 91001 covers Altadena and Pasadena 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

Las Flores Water Co. CA1910061 · Community water system · Surface water purchased
Serves 2,211 people Rules violated, past 3 years 0 Last sanitary survey Oct 8, 2025 Distance 0.5 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
Rubio Canon Land & Water Association
 6,646 0 0.7 mi
Lincoln Avenue Water Co.
 8,721 0 0.9 mi
Foothill Municipal Water Dist.
 0 2 2.0 mi
Pasadena Water and Power
Pasadena		 165,448 0 2.5 mi
Liberty Utilities Mesa Crest
 1,616 0 3.0 mi
Valley Water Co.
 10,113 0 3.2 mi
Kinneloa Irrigation Dist.
 1,808 1 3.3 mi
LA Canada Irrigation Dist.
 9,258 0 4.5 mi
Sierra Madre-City, Water Dept.
Sierra Madre		 11,000 0 5.3 mi
City of South Pasadena
South Pasadena		 25,329 0 5.9 mi
Crescenta Valley Cwd
 28,162 0 6.2 mi
Glendale-City, Water Dept.
Glendale		 192,212 0 6.3 mi
Cal-Am Water Company East Pasadena
 9,963 0 6.4 mi
Sunny Slope Water Co.
 25,252 1 6.7 mi
Cal/am Water Company San Marino
 48,065 0 6.9 mi
City of Arcadia
Arcadia		 54,236 0 7.1 mi
San Gabriel County WD
 40,154 0 7.5 mi
City of Alhambra
Alhambra		 80,279 0 7.6 mi
Valhalla Water Association
 25 1 8.4 mi
Monrovia-City, Water Dept.
Monrovia		 37,931 0 8.6 mi
Gswc-South Arcadia
 27,430 0 9.1 mi
Gswc-South San Gabriel
 26,451 0 9.4 mi
Amarillo Mutual Water Company
 3,134 0 9.5 mi
Monterey Park-City, Water Dept.
Monterey Park		 61,096 1 10.0 mi
EL Monte-City, Water Dept.
El Monte		 23,000 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
Millard Canyon Improvement Association
 42 1 0
Henninger Flats
 50 0 0
Usfs-Red Box Station A-3
 25 0 0
Usfs-Skyline Park / Mount Wilson A-4
 25 0 0
Clear Creek Outdoor Education Center
 105 0 0
Usfs-Chantry Flats-A16 Water
 113 0 0
Colby Ranch-United Methodist Camp
 180 0 0
Rancho Ybarra Christian Camp
 73 0 0
Young-Nak Presbyterian Church
 25 0 0
Martin Marietta Southern Calif Aggregate
 51 0 0
Usfs-Monte Cristo Camp T-4
 116 0 0
Irwindale Brewery Yard (iby)
 300 0 0
Angeles Crest Christian Camp
 112 1 0
Usfs-Chilao Main A-9
 50 0 0
Angeles Shooting Ranges
 490 0 0
Plant Water Well Rockview Dairy
South Gate 		45 0 0
1000 Trails / Soledad Canyon Preserve
 812 1 0
Coldbrook Campground
 38 0 0
Rancho los Amigos Hospital
 3,200 0 0
Acton la North KOA
 400 0 0
Acton Conservation Camp #11
 90 4 0
Acton Four Square Church
 50 0 0
Acton-Agua Dulce Lds Church
 150 0 0
Usfs-Crystal Lake B-13 Water
 2,000 0 0
Saint Andrews Abbey
 210 1 1
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
Huttopia Paradise Springs
 302 1 0
Usfs-Valyermo Ranger Station
 25 1 1
Agua Dulce Winery
 113 0 0
Shepherd of the Hills
 80 0 0
Living Springs Church
 50 0 0
LE Chene Restaurant Water System
 100 0 0
Camp Elk
 121 0 0
Usfs-Jackson Lake V-4
 805 0 0
Usfs-Appletree Flats V-3
 25 0 0
Texas Canyon Ranger Station
 30 0 0
Desert Aire Golf Course
 80 0 0
Mountain High East Ski Area
 150 0 0
Mount Kare Camp/kare Youth League
 59 0 0
Usfs-Big Pines V-2
 54 0 0
Los Angeles World Airports
 180 0 0
Lockheed Martin Skunk Works
 135 0 0
Anchor Retreat Center
 202 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. Retrieved from ECHO on Oct 11, 2026.