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Water wells in the Washita and Fredericksburg groups, Williamson County, Texas

Home water wells that draw from the Washita and Fredericksburg groups in Williamson County, Texas are typically 300 to 625 feet deep (median 450 ft, 219 wells drilled in the last 10 years). It accounts for 18% of the 1,229 county wells the state's model covers; the main layer is the lower Trinity (Twin Mountains and Travis Peak) (60%). They run about 103 feet shallower than the county's median well (553 ft). Estimated cost of a complete well at the median depth: $14,000 to $33,500.

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 Williamson CountyWashita and Fredericksburg across Texas

Which layer Williamson County wells draw from

Under Georgetown, Williamson County

County home wells covered by the Northern Trinity and Woodbine model (in the last 10 years).

Home wells in Williamson 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: Williamson County

Key figures

Typical depth (middle half)
300 to 625 feet
Median depth
450 feet
Deepest 10% are past
751 feet
Water level (median)
182 feet
191 wells
Yield (median)
100 gpm
135 wells, gallons per minute
Wells used
219
In the last 10 years
Share of the county's wells
18%
All years on file
575
median 450 ft, since 2002
Confidence
Standard (30 or more wells)

When the wells were finished, the water stood a median 182 feet below the surface (191 wells), well above the bottom: the typical well holds about 268 feet of water.

Which layer Williamson County wells draw from

County home wells covered by the Northern Trinity and Woodbine model (in the last 10 years).

What this layer is

The Washita and Fredericksburg groups are limestone, marl and clay between the Woodbine and the Trinity (Georgetown, Duck Creek, Kiamichi, Edwards, Comanche Peak and Walnut, among others). In Williamson, Bell and Travis counties the model's layer includes part of the Edwards limestone of the Balcones Fault Zone, but this page describes the model layer as a whole, not that aquifer.

More about the Washita and Fredericksburg groups

Depth over time

Home well depth in this layer in Williamson County has not changed meaningfully in 20 years: the median was 440 feet in 2003 to 2007 and 470 feet in 2021 to 2025 (a difference under 10% or within the margin of error).

PeriodMedian depth (ft)Wells
2001–2005440106
2006–2010460129
2011–201546099
2016–2020400115
2021–2025470117
2026under 10 wells9

Places in Williamson County with wells in this layer

Common questions

How deep is a well in the Washita and Fredericksburg groups in Williamson County?

Home water wells that draw from the Washita and Fredericksburg groups in Williamson County, Texas are typically 300 to 625 feet deep (median 450 ft, 219 wells drilled in the last 10 years).

How many Williamson County wells draw from this layer?

It accounts for 18% of the 1,229 county wells the state's model covers; the main layer is the lower Trinity (Twin Mountains and Travis Peak) (60%). For 81% of these wells the report says where the water enters and we use the middle of that interval; for the rest we use the bottom of the hole, which tends to read one layer too deep.

How deep does the water stand?

When the wells were finished, the water stood a median 182 feet below the surface (191 wells), well above the bottom: the typical well holds about 268 feet of water.

What a well costs here

At the median depth for this layer in Williamson County (450 feet), a complete home well would cost roughly $14,000 to $33,500: $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 (300 to 625 feet) the range runs from $10,000 to $44,000. 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 81% of these wells the report says where the water enters and we use the middle of that interval; for the rest we use the bottom of the hole, which tends to read one layer too deep.

How well it works: In 7,977 wells in the area of the state's Northern Trinity and Woodbine model (North and Central Texas) 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 74% of them, and that layer or the one next to it in at least 95%; among the 3,130 of those wells that the state places in a Trinity layer (Paluxy to Hosston) it is about 56%.

  • The layers come from the Texas Water Development Board's Northern Trinity and Woodbine model, with quarter mile cells, summarized here to about 1.3 miles. 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.
  • In this model every layer is at least 30 feet thick, even where the real rock is thinner or missing. Thin layers and the edges of the model are approximate.
  • Inside the Trinity this atlas does not name single model layers: it groups the Paluxy and Glen Rose (upper Trinity) and groups the Hensell, Pearsall and Hosston (lower Trinity, Twin Mountains and Travis Peak), because the check against the state's codes shows the method cannot separate them reliably.
  • "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/williamson-county/washita-fredericksburg. License CC BY 4.0. https://doi.org/10.5281/zenodo.24126380.

Sources