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Water wells in the Lower Trinity, Medina County, Texas

Home water wells that draw from the Lower Trinity in Medina County, Texas are consistently 830 to 905 feet deep (median 857 ft, 31 wells drilled in the last 10 years). It accounts for 21% of the 146 county wells the state's model covers; the main layer is the Middle Trinity (77%). They run about 322 feet deeper than the county's median well (535 ft). Estimated cost of a complete well at the median depth: $24,000 to $58,000.

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 Medina CountyLower Trinity across Texas

Which layer Medina County wells draw from

  • Middle Trinity 77% · 113 wells
  • Lower Trinity 21% · 31 wells
  • Upper Trinity 1% · 2 wells
County home wells covered by the Hill Country Trinity model (in the last 10 years).

Home wells in Medina 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: Medina County

Key figures

Typical depth (middle half)
830 to 905 feet
Median depth
857 feet
Deepest 10% are past
970 feet
Water level (median)
361 feet
30 wells
Yield (median)
30 gpm
28 wells, gallons per minute
Wells used
31
In the last 10 years
Share of the county's wells
21%
All years on file
41
median 860 ft, since 2001
Confidence
Standard (30 or more wells)

When the wells were finished, the water stood a median 361 feet below the surface (30 wells), well above the bottom: the typical well holds about 496 feet of water.

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

Too few wells per period in this layer in Medina County to compare depth over time. Since 2001, 41 home wells have been reported, with a median of 860 feet.

PeriodMedian depth (ft)Wells
2001–2005under 10 wells1
2006–2010under 10 wells6
2011–2015under 10 wells3
2016–2020under 10 wells6
2021–202586424
2026under 10 wells1

Common questions

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

Home water wells that draw from the Lower Trinity in Medina County, Texas are consistently 830 to 905 feet deep (median 857 ft, 31 wells drilled in the last 10 years).

How many Medina County wells draw from this layer?

It accounts for 21% of the 146 county wells the state's model covers; the main layer is the Middle Trinity (77%). For 100% 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 361 feet below the surface (30 wells), well above the bottom: the typical well holds about 496 feet of water.

What a well costs here

At the median depth for this layer in Medina County (857 feet), a complete home well would cost roughly $24,000 to $58,000: $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 (830 to 905 feet) the range runs from $23,500 to $61,000. 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 100% 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/medina-county/lower-trinity. License CC BY 4.0. https://doi.org/10.5281/zenodo.24126380.

Sources