Skip to content
ENES
Marketplace

Water wells in the Lower Trinity, Travis County, Texas

Home water wells that draw from the Lower Trinity in Travis County, Texas vary a lot in depth: the middle half are 265 to 708 feet deep (median 430 ft, 419 wells drilled in the last 10 years), so look at the wells closest to the tract. It is the county's main layer: 46% of the 916 wells the state's model covers. They are about as deep as the county's median well (445 ft). Estimated cost of a complete well at the median depth: $13,500 to $32,500.

Updated every day from Texas Water Development Board driller reports. Last update: November 11, 2026, using the state file of November 10, 2026.

All wells in Travis CountyLower Trinity across Texas

Which layer Travis County wells draw from

Under Austin, Travis County

County home wells covered by the Hill Country Trinity model (in the last 10 years).

Home wells in Travis County

Each dot is a home well from a state driller report, colored by depth. Tap one for its details and official report. Tap an empty spot to see what is under that point.

See underground

Well depth (ft)

  • <100
  • 100
  • 200
  • 300
  • 400
  • 600
  • 800+

Dark line: Travis County

Key figures

Typical depth (middle half)
265 to 708 feet
Median depth
430 feet
Deepest 10% are past
850 feet
Water level (median)
322 feet
234 wells
Yield (median)
25 gpm
389 wells, gallons per minute
Wells used
419
In the last 10 years
Share of the county's wells
46%
All years on file
1,312
median 400 ft, since 1994
Confidence
Standard (30 or more wells)

When the wells were finished, the water stood a median 322 feet below the surface (234 wells).

Which layer Travis County wells draw from

County home wells covered by the Hill Country Trinity model (in the last 10 years).

What this layer is

The Lower Trinity groups the Sycamore Sand, the Sligo Formation and the Hosston Formation, under the Hammett Shale. It is the deepest of the four layers in the state's Hill Country model, so wells that draw from it are the deepest and cost the most to drill.

Checked against the state's own aquifer codes: where our method names this layer, the state agrees in 53% of 426 wells. Read it as the likely layer, not a certain one.

More about the Lower Trinity

Depth over time

Home well depth in this layer in Travis County has not changed meaningfully in 20 years: the median was 380 feet in 2003 to 2007 and 440 feet in 2021 to 2025 (a difference under 10% or within the margin of error).

PeriodMedian depth (ft)Wells
2001–2005392276
2006–2010380284
2011–2015380277
2016–2020410285
2021–2025440177
202652811

Places in Travis County with wells in this layer

Common questions

How deep is a well in the Lower Trinity in Travis County?

Home water wells that draw from the Lower Trinity in Travis County, Texas vary a lot in depth: the middle half are 265 to 708 feet deep (median 430 ft, 419 wells drilled in the last 10 years), so look at the wells closest to the tract.

How many Travis County wells draw from this layer?

It is the county's main layer: 46% of the 916 wells the state's model covers. For 98% of these wells the report says where the water enters (the screen or the open hole), and we use the middle of that interval.

How deep does the water stand?

When the wells were finished, the water stood a median 322 feet below the surface (234 wells).

What a well costs here

At the median depth for this layer in Travis County (430 feet), a complete home well would cost roughly $13,500 to $32,500: $25 to $60 per foot for drilling, casing and seal, plus $2,500 to $6,500 for the pump, pressure tank, controls and hookup at the well. Across the whole middle half of depths (265 to 708 feet) the range runs from $9,000 to $49,000. This is TerraFunded's estimate from published Texas prices, not a quote, and it leaves out trenching and the line to the house. Get prices from at least two licensed drillers.

How these numbers are made

We count new and replacement domestic (home) wells with a valid depth on their report. We use the last 10 years when there are at least 30 wells; otherwise all since 2001. The median is the middle well and the middle half runs from the 25th to the 75th percentile.

To tell which layer a well draws from, we take the ground elevation at its location, subtract the depth of the interval where water enters (or the bottom of the hole when the report does not give one) and see which layer of the state's model that point falls in.

For 98% of these wells the report says where the water enters (the screen or the open hole), and we use the middle of that interval.

How well it works: In 2,665 wells in the Texas Hill Country where the State of Texas recorded the aquifer, our estimate of the formation the well draws from names the same layer of the state's model in about 76% of them, and that layer or the one next to it in at least 98%.

  • The layers come from the Texas Water Development Board's Hill Country Trinity model, with 1 mile cells. It is a regional model, not a survey of any lot: between one model point and the next, the real depth of each layer can differ.
  • "Near or below the base of the Trinity" means the well reaches the bottom of the model or passes it, often by tens of feet. Older rock that the model does not include may lie there.
  • We never use the model's water levels. The water level on this page is the one each driller measured when the well was finished.

These are depths of real wells drilled nearby, not a promise about any property. Groundwater can change over short distances and with drought. A licensed water well driller can tell you what to expect on a specific tract.

Read the full methodology · Download the data (CSV, CC BY 4.0)

How to cite

TerraFunded (2026). Texas Well Atlas: Underground. From Texas Water Development Board driller reports and groundwater availability models (data as of November 10, 2026). https://terrafunded.com/wells/travis-county/lower-trinity. License CC BY 4.0. https://doi.org/10.5281/zenodo.24126380.

Sources