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Water wells in the Middle Trinity, Blanco County, Texas

Home water wells that draw from the Middle Trinity in Blanco County, Texas are typically 380 to 544 feet deep (median 443 ft, 542 wells drilled in the last 10 years). It is the county's main layer: 70% of the 771 wells the state's model covers. They run about 33 feet deeper than the county's median well (410 ft). Estimated cost of a complete well at the median depth: $13,500 to $33,000.

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 Blanco CountyMiddle Trinity across Texas

Which layer Blanco County wells draw from

  • Middle Trinity 70% · 542 wells
  • Near or below the base of the Trinity 20% · 156 wells
  • Lower Trinity 6% · 45 wells
  • Upper Trinity 4% · 28 wells

Under Johnson City, Blanco County

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

Home wells in Blanco 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: Blanco County

Key figures

Typical depth (middle half)
380 to 544 feet
Median depth
443 feet
Deepest 10% are past
644 feet
Water level (median)
255 feet
268 wells
Yield (median)
20 gpm
477 wells, gallons per minute
Wells used
542
In the last 10 years
Share of the county's wells
70%
All years on file
975
median 423 ft, since 1999
Confidence
Standard (30 or more wells)

When the wells were finished, the water stood a median 255 feet below the surface (268 wells).

Which layer Blanco County wells draw from

  • Middle Trinity 70% · 542 wells
  • Near or below the base of the Trinity 20% · 156 wells
  • Lower Trinity 6% · 45 wells
  • Upper Trinity 4% · 28 wells
County home wells covered by the Hill Country Trinity model (in the last 10 years).

What this layer is

The Middle Trinity groups the lower member of the Glen Rose Limestone, the Hensell Sand and the Cow Creek Limestone. It is the layer most Hill Country home wells are completed in. Under it, the Hammett Shale separates it from the Lower Trinity.

Checked against the state's own aquifer codes: where our method names this layer, the state agrees in 85% of 1,503 wells.

More about the Middle Trinity

Depth over time

New home wells in this layer in Blanco County are deeper than 20 years ago: the median went from 400 feet (2003 to 2007) to 444 feet (2021 to 2025), 11% more. Deeper wells do not always mean the water dropped: a driller may be going for another layer, better water or more reserve.

PeriodMedian depth (ft)Wells
2001–2005370125
2006–2010408176
2011–2015400110
2016–2020425223
2021–2025444303
202644437

Places in Blanco County with wells in this layer

Common questions

How deep is a well in the Middle Trinity in Blanco County?

Home water wells that draw from the Middle Trinity in Blanco County, Texas are typically 380 to 544 feet deep (median 443 ft, 542 wells drilled in the last 10 years).

How many Blanco County wells draw from this layer?

It is the county's main layer: 70% of the 771 wells the state's model covers. For 97% 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 255 feet below the surface (268 wells).

What a well costs here

At the median depth for this layer in Blanco County (443 feet), a complete home well would cost roughly $13,500 to $33,000: $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 (380 to 544 feet) the range runs from $12,000 to $39,000. 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 97% 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/blanco-county/middle-trinity. License CC BY 4.0. https://doi.org/10.5281/zenodo.24126380.

Sources