ZIP code 78666 covers San Marcos, Texas in Hays County. This area is served by 73 utility providers across 5 categories. The average residential electricity rate here is 11.3¢/kWh. 74.2% of households use electricity as their primary heating fuel.
Estimated monthly utility costs
$228/month
Cost estimates from U.S. Census ACS 5-year data · Shorter bar = lower cost
Electric
Natural Gas
Water
Sewer
Internet
Business Internet
These providers offer business-class internet service in this area.
Nearby ZIP codes
Frequently asked questions
How do I set up utilities when moving to 78666?
Contact each provider separately before your move-in date. Start with electric (Bluebonnet Electric Coop, Inc) and gas (Centerpoint Energy - Entex, (713) 207-1111) since those typically need a few business days to activate. Water and sewer are often handled with one call to your local utility. Set up internet last since it may require an installation visit.
How much do utilities cost per month in 78666?
Total estimated monthly costs are around $227, which is about $156 less than the national average. Electricity is the biggest expense at roughly $125/month. Natural gas runs about $75. Water and sewer combined are around $28. Costs vary by home size, usage, and season. Estimates from U.S. Census ACS data.
Is electricity expensive in 78666?
No — electricity in San Marcos, TX costs about 24% less than the national average. Compared to Texas overall, rates here are about 17% lower. Based on 2023 NREL residential electricity rate data.
What internet providers are available in 78666?
San Marcos, TX has strong broadband coverage. Providers include AT&T (Fixed Wireless up to 100 Mbps), Astound Broadband (Cable / Fiber up to 1,500 Mbps), Brightspeed (Fiber / DSL up to 1,000 Mbps), Frontier (Fiber up to 7,000 Mbps), GVTC (Fiber / DSL up to 1,000 Mbps). Availability varies by street address. Based on FCC Broadband Data Collection filings.
What county is 78666 in?
ZIP code 78666 is in Hays County, Texas.
Disclaimer: Provider information is sourced from federal databases including HIFLD, EPA SDWIS, FCC Broadband Data, and EIA-861. Utility cost estimates are from the U.S. Census Bureau American Community Survey 5-Year Estimates. Electric rates are based on 2023 NREL data. Coverage areas are approximate and may not reflect recent changes. Please verify directly with your provider.
Data sources: U.S. Census Bureau, NREL, EIA-861, HIFLD, EPA, FCC. Last updated: April 2026.