New septic system installation in Hays County / the Central Texas Hill Country

Cost: $9,000–$18,000 for a conventional system. Engineered systems (mound, drip, aerobic) run higher — see the cost guide for the local ranges.

What decides the price

• Soil. The single biggest variable. Well-draining soil supports a simple gravity field; slow-draining or shallow soil forces a larger field or an engineered system.
• Bedrooms. Systems are sized by bedroom count.
• Lot access and terrain. Flat and open is cheap; wooded hillside means slower machine work and sometimes a pump chamber.
• Permit and inspections. County fees are modest; the contractor's design and inspection coordination are part of the quote.

Steps

1. Site evaluation and soil test with the county
2. System design and permit application
3. Installation — tank, field or unit, pump chamber if required
4. County final inspection before backfill and use

Buying land? A site evaluation before closing tells you what a system will cost — or whether the lot will support one at all.

All work is performed by TCEQ-licensed installers and licensed maintenance providers working under the county's on-site sewage facility program.

Start with a site evaluation ·