ZIP 78621 falls in Travis County, Texas, where we hold 34,543 parcels measured as septic county-wide and 337,990 on sewer. We do not have a per-ZIP parcel count for this county, so this is the county total, not a count specific to ZIP 78621.
ZCTA 78621 is not entirely inside one county. Land-area share is from the 2020 Census ZCTA-to-county relationship file.
| County | Land in this ZIP | Documents held | On septic (county) | On sewer (county) |
|---|---|---|---|---|
| Travis County, Texas | 15% | 164,420 | 34,543 | 337,990 |
| Williamson County, Texas | 14% | — | 110,116 | 176,652 |
| Lee County, Texas | 9% | 1 | — | — |
1 businesses on record with an address in this ZIP: pumping, installation, design, inspection and repair. Not an endorsement, and we take no fee.
| Company | City | Phone | Rating |
|---|---|---|---|
| StandAlone Septic & Dirt Work | Elgin | (512) 550-1716 | 5.0 (1) |
Land-area overlap is from the 2020 Census Bureau ZCTA5-to-county relationship file, not an estimate of ours. Parcel and document counts are rows we hold, not a survey of every property in the ZIP. Last verified 2026-09-01.
We hold 34,543 parcels measured as septic for Travis County, Texas as a whole, not broken out by ZIP.
ZIP 78621 spans 3 counties: Travis County, Texas, Williamson County, Texas, Lee County, Texas.