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Washita and Fredericksburg: how deep the wells are

Home water wells that draw from the Washita and Fredericksburg groups in North and Central Texas vary a lot in depth: the middle half are 180 to 400 feet deep (median 240 ft, 1,050 wells drilled in the last 10 years), so look at the wells closest to the tract. In the state's model it is limestone, marl and clay. It carries the most weight in Grayson County (37% of its wells). Estimated cost of a complete well at the median depth: $8,500 to $21,000.

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

Depth of wells in the Washita and Fredericksburg groups, by countyThe dot is the median and the bar the middle half for each county. The table below has the figures.0200400600800 ftJohnsonJohnson: 200–260 ftJohnson: 228 ft228WilliamsonWilliamson: 300–625 ftWilliamson: 450 ft450GraysonGrayson: 200–400 ftGrayson: 300 ft300BellBell: 106–211 ftBell: 159 ft159TarrantTarrant: 140–220 ftTarrant: 180 ft180HillHill: 220–352 ftHill: 260 ft260BosqueBosque: 180–280 ftBosque: 200 ft200CookeCooke: 160–270 ftCooke: 200 ft200DentonDenton: 200–560 ftDenton: 240 ft240EllisEllis: 380–780 ftEllis: 440 ft440McLennanMcLennan: 60–80 ftMcLennan: 80 ft80TravisTravis: 325–500 ftTravis: 410 ft410

Under Georgetown, Williamson County

Dot: median. Bar: middle half (25th to 75th percentile). Counties with the most wells in this layer.

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.

Units the model puts in this layer: Washita Group (Buda, Del Rio, Grayson, Mainstreet, Pawpaw, Weno, Denton, Fort Worth, Duck Creek, Georgetown) and Fredericksburg Group (Kiamichi, Edwards, Goodland, Comanche Peak, Walnut); includes part of the Edwards (Balcones Fault Zone) Aquifer in the south.

Source of the layers: TWDB's Northern Trinity and Woodbine model, with quarter mile cells, summarized here to about 1.3 miles.

Key figures

Typical depth (middle half)
180 to 400 feet
Median depth
240 feet
Deepest 10% are past
610 feet
Water level (median)
120 feet
783 wells
Yield (median)
15 gpm
832 wells, gallons per minute
Wells used
1,050
In the last 10 years
All years on file
2,579
median 240 ft, since 2001
Confidence
Standard (30 or more wells)

Counties where homes draw from this layer

Only counties with at least 10 wells in the layer. The share is of the county's wells that the model covers.

Depth of wells in the Washita and Fredericksburg groups, by countyThe dot is the median and the bar the middle half for each county. The table below has the figures.0200400600800 ftJohnsonJohnson: 200–260 ftJohnson: 228 ft228WilliamsonWilliamson: 300–625 ftWilliamson: 450 ft450GraysonGrayson: 200–400 ftGrayson: 300 ft300BellBell: 106–211 ftBell: 159 ft159TarrantTarrant: 140–220 ftTarrant: 180 ft180HillHill: 220–352 ftHill: 260 ft260BosqueBosque: 180–280 ftBosque: 200 ft200CookeCooke: 160–270 ftCooke: 200 ft200DentonDenton: 200–560 ftDenton: 240 ft240EllisEllis: 380–780 ftEllis: 440 ft440McLennanMcLennan: 60–80 ftMcLennan: 80 ft80TravisTravis: 325–500 ftTravis: 410 ft410
Dot: median. Bar: middle half (25th to 75th percentile). Counties with the most wells in this layer.
CountyMedian depth (ft)WellsShare of the county's wells
Johnson County22824422%
Williamson County45021918%
Grayson County30013937%
Bell County15913827%
Tarrant County180845%
Hill County2606418%
Bosque County200379%
Cooke County200376%
Denton County240334%
Ellis County8602013%
McLennan County801214%
Travis County410121%

Places where it is the main layer

Where it sits among the model's layers

From top to bottom, with the median depth of the home wells that draw from each:

Layer (state's model)RockMedian depth (ft)Wells
Above the Woodbineshale, chalk and marl1601,739
Woodbinesandstone with shale2601,037
Washita and Fredericksburglimestone, marl and clay2401,050
Upper Trinity (Paluxy and Glen Rose)sandstone, limestone and marl2809,322
Lower Trinity (Twin Mountains and Travis Peak)sandstone with shale and limestone34012,230

Depth over time

Home well depth in this layer has not changed meaningfully in 20 years: the median was 265 feet in 2003 to 2007 and 240 feet in 2021 to 2025 (a difference under 10% or within the margin of error).

PeriodMedian depth (ft)Wells
2001–2005260468
2006–2010260544
2011–2015240444
2016–2020240482
2021–2025240583
202625258

Common questions

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

Home water wells that draw from the Washita and Fredericksburg groups in North and Central Texas vary a lot in depth: the middle half are 180 to 400 feet deep (median 240 ft, 1,050 wells drilled in the last 10 years), so look at the wells closest to the tract.

What is the Washita and Fredericksburg groups?

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.

How deep does the water stand in these wells?

When the wells were finished, the water stood a median 120 feet below the surface (783 wells).

What a well in this layer costs

At the median depth for this layer (240 feet), a complete home well would cost roughly $8,500 to $21,000: $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 (180 to 400 feet) the range runs from $7,000 to $30,500. 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 91% 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 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/formations/washita-fredericksburg. License CC BY 4.0. https://doi.org/10.5281/zenodo.24126380.

Sources