Where to Live in San Diego County: Towns Compared by Transit, Services and Rules

By Matthew Martinez, Founder, CEO & Managing Broker, Diamond Real Estate Group. California DRE #01869679.

San Diego County is easiest to compare in three bands: the coastal cities along I-5 and the COASTER line, the inland cities along the Trolley, SPRINTER and I-15/I-8 corridors, and the large unincorporated backcountry, where the County is the land-use authority and many homes are on wells and septic. Within each band, the details that actually change your ownership are which of the 18 cities (or the unincorporated county) has jurisdiction, whether the parcel is in the Coastal Zone, which water agency serves it, and how that city treats short-term rentals.

This guide compares places only by housing types and lot sizes, jurisdiction, water and wastewater, transportation, local rules and ownership costs. It does not describe residents, safety or schools, and it gives no prices or market statistics. For listings, start on our San Diego County homes page.

Cities and the unincorporated county

The County lists 18 incorporated cities. Along the coast: Oceanside, Carlsbad, Encinitas, Solana Beach, Del Mar, San Diego, Coronado and Imperial Beach. Inland and in the South Bay: Vista, San Marcos, Escondido, Poway, Santee, El Cajon, La Mesa, Lemon Grove, National City and Chula Vista.

Everything outside city limits is unincorporated San Diego County, including Fallbrook, Valley Center, Ramona, Rancho Santa Fe, Alpine, Lakeside, Spring Valley, Bonita, Julian and Borrego Springs. There, the County provides services a city normally would, such as law enforcement, fire protection, roads and building permits. A city name in the mailing address does not prove jurisdiction; our guide to city or unincorporated property shows how to check.

How the County plans unincorporated growth

The County’s General Plan, updated in 2011, focuses development in village cores to protect rural lands and places 80% of planned dwelling-unit capacity where imported water can be distributed. The County has land-use jurisdiction over 772,239 acres, about 35% of the unincorporated area; tribal, state, federal and military lands make up the rest. Practically, that means backcountry parcels outside villages tend to be large lots on private systems, while new subdivisions in the unincorporated county cluster where water service exists.

Town-by-town comparison

Where the table names a water agency, it is a Water Authority member whose name matches the city; most cities are split among several agencies, so confirm the serving agency for the exact parcel. Sources are below.

Water, sewer and septic

The San Diego County Water Authority wholesales water to member agencies, which serve homes, set rates and send bills. Its map list shows 22 members, including the cities of San Diego, Oceanside, Escondido, Poway, Del Mar and National City; districts such as Carlsbad MWD, Helix, Olivenhain, Otay, Padre Dam, Ramona, Rincon del Diablo, San Dieguito, Santa Fe ID, Vallecitos, Valley Center, Vista ID and Yuima; Lakeside Water District; Sweetwater Authority; and Camp Pendleton. Rates and connection rules differ by agency, so look up the address.

Outside sewer service, the County’s Department of Environmental Health and Quality regulates septic systems: design review, installation inspections, percolation test and repair permits. It keeps septic design records for permitted properties, available through its document library or a public records request. Ask for them before you buy a backcountry home. Our rural water and wastewater guide lists what to request.

Transportation

• Trolley. MTS runs four Trolley lines: the Blue Line (UTC and La Jolla through Old Town, downtown, National City and Chula Vista to San Ysidro), the Orange Line (downtown through Lemon Grove and La Mesa to El Cajon), the Green Line (downtown, Old Town, Mission Valley and SDSU to La Mesa and El Cajon) and the Copper Line (El Cajon to Santee).
• COASTER. NCTD’s commuter rail serves eight stations between Oceanside and downtown San Diego; NCTD lists Oceanside, Carlsbad, Encinitas, Solana Beach, Sorrento Valley and San Diego among the communities it serves.
• SPRINTER. The SPRINTER hybrid rail runs about 22 miles along the SR 78 corridor between Oceanside and Escondido, with 15 stations including Vista and San Marcos.
• Highways. I-5 runs the coast, I-15 and I-805 run inland north-south, I-8 runs east from Mission Valley through La Mesa and El Cajon, and SR 78, SR 52, SR 56, SR 94 and SR 125 connect them. Most of the unincorporated backcountry is reached by highway only.

Short-term and vacation rental rules

• City of San Diego. Rentals under a month need a short-term residential occupancy license. Tier 1 (20 days a year or fewer) and Tier 2 (home sharing) are unlimited. Whole-home Tier 3 licenses are capped at 1% of the city’s housing units outside Mission Beach, and Tier 4 Mission Beach licenses at 30% of Mission Beach housing units; as of the city’s October 23, 2026 update, Tier 3 had 807 licenses remaining and Tier 4 had none, with a waitlist. Licenses do not transfer to a new owner or another property.
• Coronado. Short-term vacation rentals are prohibited in residential zones; a rental must last at least 26 consecutive days.
• Carlsbad. Short-term vacation rentals may operate only in the Coastal Zone (generally within 1,000 yards of the mean high tide line) and the La Costa Resort and Spa Master Plan area, with an annual permit and business license. ADUs approved after January 1, 2020 must be rented for more than 30 days.
• Other cities and the unincorporated county. Rules vary and change; confirm with the city or County before you buy.

Long-term rental rules

The statewide Tenant Protection Act caps most rent increases at the lower of 10% or 5% plus inflation and adds just-cause rules after 12 months, per the California Attorney General. The City of San Diego’s Residential Tenant Protection Ordinance fact sheet describes just-cause protection from the first day of tenancy (fixed leases of three months or less excepted) and no-fault relocation assistance of two months’ rent, or three for seniors and tenants with disabilities. The sheet was published before the council’s April 2023 vote, so confirm current terms with the city. See also buying a tenant-occupied property.

Ownership costs that differ by place

Transfer tax. The County recorder collects the documentary transfer tax at $0.55 per $500 of value under Revenue and Taxation Code 11911. The recorder’s page lists no separate city transfer tax; confirm for your city with escrow before closing. See California transfer tax.

Mello-Roos and special assessments. Community Facilities District taxes appear on the bill as a CFD line with the district’s phone number, and the County only collects them. Look up fixed charges by parcel before you compare two homes. Our ownership cost comparison shows what to request, and plan for a supplemental tax bill.

Coastal Zone and fire hazard. Coastal parcels can need a coastal development permit for work, and backcountry parcels may sit in a mapped fire hazard severity zone that affects insurance. See our guides to Coastal Zone property records and wildfire, insurance and access.

Choosing a short list

1. Pick a band: coastal I-5, inland rail corridors or backcountry.
2. Decide whether you need a Trolley, COASTER or SPRINTER station within reach.
3. If you’ll rent short term, rule out cities and zones where it is barred.
4. Confirm jurisdiction, water agency, sewer or septic, and CFD charges for the exact parcel.

We can pull parcel records and listings for your short list; start on our buyer page or contact us.

Questions people ask

How many cities are in San Diego County?

Eighteen. Communities such as Fallbrook, Ramona, Valley Center, Alpine, Lakeside and Rancho Santa Fe are unincorporated, so County planning and permits apply.

Which San Diego County cities have Trolley service?

San Diego, National City, Chula Vista, Lemon Grove, La Mesa, El Cajon and Santee are on MTS Trolley lines.

Where does the COASTER stop?

At eight stations between Oceanside and downtown San Diego. NCTD lists Oceanside, Carlsbad, Encinitas, Solana Beach, Sorrento Valley and San Diego among the communities served.

Can I buy a home in San Diego and rent it short term?

Only with a city license. Part-time and home-sharing licenses are unlimited, but whole-home licenses are capped, Mission Beach had none left at the city’s October 2026 update, and licenses don’t transfer with a sale.

Are vacation rentals allowed in Coronado?

Not in residential zones. Rentals there must be at least 26 consecutive days.

Is there a city transfer tax in San Diego County?

The County recorder’s page lists only the county rate of $0.55 per $500. Confirm with escrow whether any city charge applies to your sale.

Will a backcountry home be on septic?

Often. Where there is no sewer, the County’s Department of Environmental Health and Quality permits septic systems and keeps design records for permitted properties.

Sources & notes

1. County of San Diego: County overview.
2. County of San Diego PDS: General Plan.
3. San Diego County Water Authority: Member agencies.
4. County DEHQ: Septic systems.
5. MTS: Trolley.
6. NCTD: COASTER and SPRINTER.
7. City of San Diego Treasurer: Short-term residential occupancy (Oct. 23, 2026 update).
8. City of Coronado: Code enforcement.
9. City of Carlsbad: Short-term vacation rentals.
10. California Attorney General: Landlord-tenant issues.
11. City of San Diego: Tenant Protection Ordinance fact sheet (April 2023).
12. San Diego County Assessor/Recorder/County Clerk: Recording.
13. County Auditor and Controller: Property tax FAQ.

Notes: Water agencies in the table are examples; confirm the serving agency for the exact parcel. Short-term rental rules for cities other than San Diego, Coronado and Carlsbad, and for the unincorporated county, were not verified for this guide. The adopted text of the City of San Diego tenant ordinance could not be opened; terms are from the city’s pre-adoption fact sheet. Rules change; verify before you buy.

General information, not legal, tax or lending advice. Updated November 2026. Primary sources are linked in this guide.

Related: San Diego County homes · Unincorporated San Diego County · City or unincorporated property · Compare ownership costs