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How deep are water wells in Round Rock, Texas?

Home water wells in and around Round Rock, Texas are typically 499 to 872 feet deep (median 720 ft, 72 wells drilled in the last 10 years). Most draw from the upper Trinity (Paluxy and Glen Rose, 58%), and 42% draw from the Washita and Fredericksburg groups, according to the state's Northern Trinity and Woodbine model (TWDB). New wells run about 61% deeper than 20 years ago (median 500 ft in 2003 to 2007, 805 ft in 2021 to 2025). Estimated cost of a complete well at the median depth: $20,500 to $49,500.

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

See the wells and layers at an exact pointWilliamson County
What is under Round Rock, TexasUnderground column at the center of Round Rock: median well 720 ft, middle half 499 to 872 ft, water at 406 ft, and the layers of the state's model with their thickness.Above the Woodbine: 0 to 26 ftWoodbine: 26 to 47 ftWashita and Fredericksburg: 47 to 672 ftWashita and Frederick…Upper Trinity: 672 to 1,566 ftUpper Trinitycontinues to 2,156 ft02505007501,0001,250ftGround level · 723 ft above sea levelMedian well: 720 ftWater standing in the well from 406 ftWater level406 ftMiddle half499–872 ftMedian well720 ft

Under Round Rock, Williamson County

Layers at the center of Round Rock from TWDB's Northern Trinity and Woodbine model (quarter mile cells, summarized here to about 1.3 miles), at true depth scale. The well and the water are the median of 72 real wells.

Home wells in and around Round Rock

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+

Dashed line: Round Rock and about 2 miles around it

Key figures

Typical depth (middle half)
499 to 872 feet
Median depth
720 feet
Deepest 10% are past
900 feet
Water level (median)
406 feet
63 wells
Yield (median)
50 gpm
61 wells, gallons per minute
Wells used
72
In the last 10 years
Inside the city limits
21
the rest within 2 miles
All years on file
216
median 600 ft, since 2000
Confidence
Standard (30 or more wells)

When the wells were finished, the water stood a median 406 feet below the surface (63 wells).

What is under Round Rock, TexasUnderground column at the center of Round Rock: median well 720 ft, middle half 499 to 872 ft, water at 406 ft, and the layers of the state's model with their thickness.Above the Woodbine: 0 to 26 ftWoodbine: 26 to 47 ftWashita and Fredericksburg: 47 to 672 ftWashita and Frederick…Upper Trinity: 672 to 1,566 ftUpper Trinitycontinues to 2,156 ft02505007501,0001,250ftGround level · 723 ft above sea levelMedian well: 720 ftWater standing in the well from 406 ftWater level406 ftMiddle half499–872 ftMedian well720 ft
Layers at the center of Round Rock from TWDB's Northern Trinity and Woodbine model (quarter mile cells, summarized here to about 1.3 miles), at true depth scale. The well and the water are the median of 72 real wells.

Which formation do wells in Round Rock draw from?

Most draw from the upper Trinity (Paluxy and Glen Rose, 58%), and 42% draw from the Washita and Fredericksburg groups, according to the state's Northern Trinity and Woodbine model (TWDB).

Layer (state's model)ShareWellsTypical depth (ft)
Upper TrinityPaluxy and Glen Rose58%42790–890
Washita and Fredericksburg42%30322–590

For 92% of these wells the report says where the water enters (the screen or the open hole), and we use the middle of that interval.

The layers under the center of Round Rock

From the state's model, at 723 feet above sea level. These are the model's depths at that one point, not those of any particular lot.

Depths in feet below ground.
Layer (state's model)Top (ft)Bottom (ft)Thickness (ft)
Above the Woodbineshale, chalk and marl02626
Woodbinesandstone with shale264721
Washita and Fredericksburglimestone, marl and clay47672625
Upper Trinitysandstone, limestone and marl6721,566893
Lower Trinitysandstone with shale and limestone1,5662,156590

Depth over time

New home wells in and around Round Rock are deeper than 20 years ago: the median went from 500 feet (2003 to 2007) to 805 feet (2021 to 2025), 61% 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
2001–200550034
2006–201054547
2011–201570156
2016–202059039
2021–202580536
2026under 10 wells3

What a well costs in Round Rock

At the median depth for Round Rock (720 feet), a complete home well would cost roughly $20,500 to $49,500: $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 (499 to 872 feet) the range runs from $15,000 to $59,000. 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.

Where it sits

Nearby places

Median depth of home wells in each place.

All Texas cities and towns

Common questions

How deep do you have to drill a well in Round Rock, Texas?

Home water wells in and around Round Rock, Texas are typically 499 to 872 feet deep (median 720 ft, 72 wells drilled in the last 10 years). One in ten goes past 900 feet. The depth a given tract needs depends on where it sits and what layers the driller hits.

What aquifer or formation do wells in Round Rock draw from?

Most draw from the upper Trinity (Paluxy and Glen Rose, 58%), and 42% draw from the Washita and Fredericksburg groups, according to the state's Northern Trinity and Woodbine model (TWDB). This is an estimate from the state's regional model, not a survey of the lot.

How much does a water well cost in Round Rock?

At the median depth (720 feet), a complete well would cost roughly $20,500 to $49,500, by TerraFunded's estimate from published Texas driller prices. The real price comes from a licensed driller's quote.

How deep is the water in Round Rock?

When the wells were finished, the water stood a median 406 feet below the surface (63 wells). The level moves with drought and from one well to the next.

Do I need a permit to drill a well in Round Rock?

In the state's boundary file (current as of November 2019) no groundwater conservation district covers Round Rock. Districts created or enlarged since then are missing from that file, so confirm with the county or TWDB before drilling. Anywhere in Texas the well must be drilled by a licensed driller, who files the report with the state.

How these numbers are made

We count new and replacement domestic (home) wells whose coordinates fall inside the place boundary or within 2 miles of it. 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 92% 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/places/round-rock-tx. License CC BY 4.0. https://doi.org/10.5281/zenodo.24126380.

Sources