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How deep are water wells in San Marcos, Texas?

Home water wells in and around San Marcos, Texas are typically 220 to 330 feet deep (median 300 ft, 45 wells drilled in the last 10 years). Estimated cost of a complete well at the median depth: $10,000 to $24,500.

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 pointHays County
What is under San Marcos, TexasUnderground column at the center of San Marcos: median well 300 ft, middle half 220 to 330 ft, water at 150 ft.No state layer model here yet0100200300400500ftGround levelMedian well: 300 ftWater standing in the well from 150 ftWater level150 ftMiddle half220–330 ftMedian well300 ft

Under San Marcos, Hays County

The well and the water are the median of 45 real wells. This atlas does not have a state layer model for this area yet.

Home wells in and around San Marcos

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: San Marcos and about 2 miles around it

Key figures

Typical depth (middle half)
220 to 330 feet
Median depth
300 feet
Deepest 10% are past
458 feet
Water level (median)
150 feet
43 wells
Yield (median)
20 gpm
31 wells, gallons per minute
Wells used
45
In the last 10 years
Inside the city limits
8
the rest within 2 miles
All years on file
150
median 300 ft, since 1996
Confidence
Standard (30 or more wells)

When the wells were finished, the water stood a median 150 feet below the surface (43 wells).

What is under San Marcos, TexasUnderground column at the center of San Marcos: median well 300 ft, middle half 220 to 330 ft, water at 150 ft.No state layer model here yet0100200300400500ftGround levelMedian well: 300 ftWater standing in the well from 150 ftWater level150 ftMiddle half220–330 ftMedian well300 ft
The well and the water are the median of 45 real wells. This atlas does not have a state layer model for this area yet.

Which formation do wells in San Marcos draw from?

We cannot say yet for San Marcos. This atlas assigns layers with the TWDB layered models processed so far (the Northern Trinity and Woodbine model, the Hill Country Trinity model, the northern Gulf Coast Aquifer model and the High Plains Aquifer System model), and none covers this area with enough wells. The depth, water level and yield on this page do come from the real wells here.

See the aquifers mapped under Hays County

Depth over time

There are not enough wells in both 2003 to 2007 and 2021 to 2025 (at least 30 in each) to say with confidence whether wells in and around San Marcos are getting deeper. For reference, the median was 240 feet in 2001 to 2005 (25 wells) and 280 feet in 2021 to 2025 (25 wells).

PeriodMedian depth (ft)Wells
2001–200524025
2006–201028031
2011–201530046
2016–202032019
2021–202528025
2026under 10 wells3

What a well costs in San Marcos

At the median depth for San Marcos (300 feet), a complete home well would cost roughly $10,000 to $24,500: $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 (220 to 330 feet) the range runs from $8,000 to $26,500. 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.

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 San Marcos, Texas?

Home water wells in and around San Marcos, Texas are typically 220 to 330 feet deep (median 300 ft, 45 wells drilled in the last 10 years). One in ten goes past 458 feet. The depth a given tract needs depends on where it sits and what layers the driller hits.

How much does a water well cost in San Marcos?

At the median depth (300 feet), a complete well would cost roughly $10,000 to $24,500, 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 San Marcos?

When the wells were finished, the water stood a median 150 feet below the surface (43 wells). The level moves with drought and from one well to the next.

Do I need a permit to drill a well in San Marcos?

San Marcos is inside the Edwards Aquifer Authority. Groundwater conservation districts in Texas can require registering or permitting a new well, keeping set distances from property lines and other wells, and paying fees. Rules differ from district to district: ask the district before drilling.

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.

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/san-marcos-tx. License CC BY 4.0. https://doi.org/10.5281/zenodo.24126380.

Sources