Living in Castaic, CA: what to set up and who to call
Castaic has no town government of its own, so Los Angeles County runs its elections and most services, and its children attend Castaic Union School District. Adventist Health Simi Valley, 14.5 miles away, is the nearest emergency room.
I’m new in town
What to set up in Castaic, and who provides it. Tap an answer for the details and where they come from.
Power, water and internet
Who to call to start service at a new address in Castaic.
Power comes from Southern California Edison
Southern California Edison (Southern California Edison Co), an investor-owned utility, serves all of Castaic. Its homes paid an average of 31.5¢ per kWh in 2025, about $149 a month (its average across California, for customers on its standard service). California lets you buy power from another supplier; 30% of Southern California Edison’s home customers do, and Southern California Edison still delivers it.
Service territory: HIFLD Electric Retail Service Territories (map dated Aug 2023). Prices and customers: EIA-861, 2025.
Water comes from Santa Clarita Valley Water Agency
Santa Clarita Valley Water Agency supplies Castaic: about 19% of residents live in its service area. About 80% of homes are outside any mapped community water system, most likely on private wells, which EPA doesn’t regulate. It draws surface water and serves 294,090 people in all.
No health-based violations reported to EPA in the five years to October 2026, like 86% of the 84 systems serving 250,001–500,000 people.
The latest lead result on file, the 90th percentile of homes sampled in Jan 2023–Dec 2025, was 0.0 ppb, below the 15 ppb action level that applied. Results below detection are reported as 0, so 0 doesn’t mean no lead at any tap.
The system’s full record: EPA ECHO report
EPA SDWIS via Envirofacts (violations pulled Oct 9, 2026) and ECHO (lead samples, 2026Q3); service area: EPA Community Water System Service Area Boundaries v3.0. Violations are counted by the start of their compliance period. CA1910240.
4 home internet providers serve Castaic
99% of 5,540 addresses can get 100/20 Mbps; 9% can get fiber.
| Provider | Technology | Addresses | Fastest (Mbps) |
|---|---|---|---|
| Spectrum | Cable, Fiber | 99% | 1,000/35 |
| AT&T | DSL, Fiber, Fixed wireless | 84% | 5,000/5,000 |
| T-Mobile | Fixed wireless | 34% | 25/3 |
| Verizon | Fixed wireless | 13% | 300/20 |
FCC National Broadband Map, as of December 2025. Availability as providers report it, not speeds people get.
We don’t have Castaic’s trash rules yet
Pickup rules, the dump and recycling in Castaic.
Where your child goes to school
Public school districts and the school path by grade.
Castaic is in two districts that split the grades: Castaic Union School District and William S. Hart Union High School District.
A−School gradeSee Schools →U.S. Department of Education, NCES Common Core of Data, 2024–25. Enrollment rules and registration are the district’s.
No town hall: the county runs things
Castaic is unincorporated, so Los Angeles County is the local government.
Election office: FVAP local election office directory, updated Sep 2025; jurisdictions: EAC EAVS 2024. Registration rules and links: vote.gov, updated Nov 18, 2024.
Castaic is in ZIP code 91384
ZIP codes where Castaic residents live, with the share of the town in each.
| ZIP | Post office name | Share of Castaic | ZIP’s residents in Castaic |
|---|---|---|---|
| 91384 | Castaic, CA | 100% | 66% |
91310 is P.O. box or single-organization ZIP with no homes.
Census 2020 ZIP Code Tabulation Areas, by census block; post office names: GeoNames (CC BY 4.0). ZIPs created since 2020 are missing.
Getting around, the ER and the library
One line each; the subject pages have the rest.
ER: CMS hospital data. Library: IMLS Public Libraries Survey, FY2024.
Questions about living in Castaic
Who supplies Castaic’s drinking water, and has it had violations?
Santa Clarita Valley Water Agency (EPA ID CA1910240). It reported no health-based violations to EPA in the five years to October 2026; 86% of systems its size had none. Its latest lead 90th percentile was 0.0 ppb (Jan 2023–Dec 2025), against a 15 ppb action level.
Who provides electricity in Castaic?
Southern California Edison (Southern California Edison Co), an investor-owned utility. Its homes paid about 31.5¢ per kWh in 2025 (EIA).
What internet providers serve Castaic?
Spectrum, AT&T, T-Mobile, Verizon (FCC, as of December 2025).
What ZIP codes are in Castaic?
91384. Census 2020 ZIP Code Tabulation Areas.
What school district is Castaic in?
Castaic Union School District and William S. Hart Union High School District.
How do I register to vote in Castaic?
In California you can register online until 15 days before Election Day, in person up to and including Election Day, or by mail (postmarked 15 days before). Elections here are run by the Los Angeles Registrar-Recorder County Clerk. Check your registration at voterstatus.sos.ca.gov.
Sources & dates
Every answer above names its source. Here they are with their dates.
- Water: EPA SDWIS (Envirofacts, pulled Oct 9, 2026), ECHO SDWA 2026Q3, EPA CWS Service Area Boundaries v3.0.
- Power: HIFLD Electric Retail Service Territories (map Aug 2023); EIA-861 final 2025.
- Trash: OpenStreetMap, Geofabrik extract of Oct 9, 2026. © OpenStreetMap contributors (ODbL).
- ZIP codes: Census 2020 ZCTA relationship files; GeoNames postal codes (CC BY 4.0).
- Schools: NCES Common Core of Data, 2024–25.
- Registration: vote.gov, updated Nov 18, 2024 (read Oct 10, 2026). Official sites and area codes: Wikidata.
- Election office: FVAP local election office directory (fetched Oct 10, 2026; each record dated), EAC EAVS 2024 jurisdictions; registration and lookup links from vote.gov’s state data, checked Oct 10, 2026.
- Internet: FCC National Broadband Map, as of December 2025.