Planning a well in Collin County?

Welcome to Collin County, Texas — DFW Well Service provides water well drilling and pump repair across Collin County

Water Well Drilling & Service in Collin County, Texas

Collin County sits over the Woodbine aquifer system (confined). Most residential wells target the Woodbine Group / Woodbine Aquifer; depth varies meaningfully across the county and is best estimated from neighboring TWDB well records. Drilling is regulated by the North Texas GCD, which requires a pre-drilling permit.

What’s Under Collin County: a Layer-by-Layer Look

About this diagram

This cross-section shows the actual rock formations beneath Collin County, from topsoil down to the Woodbine aquifer system.

Tap any layer in the image, or any layer in the list, to explore each layer and what it means for drilling a well on your property.

Isometric geological cross-section cube illustration showing Collin County, Texas stratigraphy — Topsoil, Surface materials and younger Upper Cretaceous units above the Woodbine, Woodbine Group / Woodbine Aquifer, Washita and Fredericksburg Groups, and the Woodbine aquifer at the base.
Hover or tap a layer in the cube to see formation details.

Collin County stratigraphy — top to bottom

Topsoil — Blackland Prairie vertisol

0–10 ft

Dark reddish-brown clay loam that swells when wet and shrinks when dry.
Austin Chalk

10–150 ft

Austin Chalk — chalk, marl, and limestone forming the upper part of the Upper Cretaceous cover above the Woodbine; low-permeability and not a dependable residential aquifer.
Eagle Ford transition

150–200 ft

Eagle Ford Shale — dark calcareous shale beneath the Austin Chalk; a confining unit between the chalk and the Woodbine sands, not water-bearing.
Woodbine Formation

200–400 ft

Sandstone interbedded with shale and clay — three water-bearing zones, the lower two typically developed. The primary aquifer for central and eastern Collin County; water quality degrades eastward toward the Hunt County line.
Primary aquifer target

Collin County Quick Facts

Primary Aquifer
Woodbine

Secondary: Trinity

Typical Well Depth
Varies by location

We estimate from nearby well records

Groundwater District
North Texas GCD
Confinement
confined

Cities We Serve in Collin County

What's Under Collin County: the Geology Story

Drilling in Collin County means starting in topsoil, working through Surface materials and younger Upper Cretaceous units above the Woodbine, to reach the Woodbine Group / Woodbine Aquifer — the producing zone for most domestic wells.

The full layer-by-layer stratigraphy is laid out under the cube above. Well depth in Collin County varies by property location and overburden thickness; your driller can review TWDB records for neighboring wells to refine the expected completion zone before drilling.

Permits & Regulations in Collin County

Collin County wells are regulated by the North Texas GCD. A pre-drilling permit is required before any new well is constructed. DFW Well Service submits the permit application as part of our drilling process.

Full Collin County permit & regulations →

Frequently Asked Questions about Collin County Wells

What aquifer is under Collin County?
Collin County wells primarily produce from the Woodbine aquifer system (confined). Trinity is a secondary target in parts of the county.
How deep are wells typically drilled in Collin County?
Residential well depth in Collin County varies meaningfully with property location and the producing formation, so there's no single countywide figure we can responsibly quote. Your driller can review TWDB well records for neighboring properties to estimate the expected depth before drilling, and the per-formation geology of the county is laid out on this page.
Does Collin County require a permit to drill a water well?
Yes. You need a permit before drilling. The North Texas GCD — the local district that permits wells — covers Collin, Cooke, and Denton counties. See the Collin County permit and regulations page for the full process.
What's the main producing formation in Collin County?
The primary producing formation is the Woodbine Group / Woodbine Aquifer — The main water source (the aquifer) for central and eastern Collin County. It reaches the surface there — what geologists call the outcrop — then tilts deeper to the east, where water quality drops off toward the Hunt County line. The layer is sandstone mixed with shale and clay, with three water-bearing zones; wells usually tap the lower two. Most Collin County residential wells are completed in this interval.

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