Planning a well in Johnson County?

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

Water Well Drilling & Service in Johnson County, Texas

Johnson County sits over the Trinity (Paluxy / Glen Rose / Hensell / Hosston) aquifer system (outcrop/shallow subcrop in western Johnson County; deep confined beneath Eagle Ford/Austin Chalk in eastern Johnson County). Most residential wells target the Paluxy Sand (Trinity upper unit); depth varies meaningfully across the county and is best estimated from neighboring TWDB well records. Drilling is regulated by the Prairielands GCD, which requires a pre-drilling permit. Local water quality consideration: Hard water from dissolved calcium carbonate.

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

About this diagram

This cross-section shows the actual rock formations beneath Johnson County, from topsoil down to the Trinity (Paluxy / Glen Rose / Hensell / Hosston) 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 Johnson County, Texas stratigraphy — Topsoil, Austin Chalk (eastern Johnson County confining unit), Eagle Ford Shale (eastern Johnson County confining unit), Washita Group (Main Street, Weno, Denton limestones and shales), Fredericksburg Group (Edwards Limestone, Comanche Peak, Walnut Clay), Paluxy Sand (Trinity upper unit), Glen Rose Formation, Hosston Conglomerate (Trinity basal sand; = Twin Mountains), and the Trinity (Paluxy / Glen Rose / Hensell / Hosston) aquifer at the base.
Hover or tap a layer in the cube to see formation details.

Johnson County stratigraphy — top to bottom

Topsoil — Blackland Prairie / Cross Timbers fringe

0–15 ft

Dark black clay in the east (it swells and shrinks with moisture), giving way to sandier Cross Timbers loam in the west.
Paluxy Sand (Trinity upper unit)

outcrop west; deep east

The Trinity layer most actively pumped in Johnson County (Prairielands GCD planning). It is at or near the surface in the west and lies deep beneath confining layers in the east. The rock is buff-to-tan sandstone.
Primary aquifer target
Glen Rose Formation

below Paluxy

Middle Trinity limestone and shale — a confining, less-productive layer. Note the Glen Rose is present here in Johnson County, unlike Cooke County and northern Denton County where it is missing.
Hosston Conglomerate (Trinity basal sand; = Twin Mountains)

deepest Trinity

The deepest Trinity layer and the most productive once a well reaches it — the same basal sand-and-conglomerate called the Twin Mountains in north-central Texas.
Aquifer

Johnson County Quick Facts

Primary Aquifer
Trinity (Paluxy / Glen Rose / Hensell / Hosston)

Secondary: Woodbine (subsurface across central and eastern Johnson County)

Typical Well Depth
Varies by location

We estimate from nearby well records

Groundwater District
Prairielands GCD
Confinement
outcrop/shallow subcrop in western Johnson County; deep confined beneath Eagle Ford/Austin Chalk in eastern Johnson County

Water Quality Notes

  • Hard water from dissolved calcium carbonate
  • Higher total dissolved solids (TDS, how mineral-heavy the water is) downdip (farther down where the layers tilt deeper) — eastern Johnson County, the deep Trinity, and the deep Woodbine
  • Iron and manganese, common where the Trinity reaches the surface (its outcrop) and in the Woodbine
  • Occasional hydrogen sulfide (a rotten-egg smell)

Cities We Serve in Johnson County

What's Under Johnson County: the Geology Story

Drilling in Johnson County means starting in topsoil, working through Brazos River alluvium (southwestern Johnson County border), Austin Chalk (eastern Johnson County confining unit), Eagle Ford Shale (eastern Johnson County confining unit), Woodbine Formation, Washita Group (Main Street, Weno, Denton limestones and shales), Fredericksburg Group (Edwards Limestone, Comanche Peak, Walnut Clay), Paluxy Sand (Trinity upper unit), Glen Rose Formation, Hensell Sand (Trinity lower sand), to reach the Hosston Conglomerate (Trinity basal sand; = Twin Mountains) — the producing zone for most domestic wells.

The full layer-by-layer stratigraphy is laid out under the cube above. Well depth in Johnson 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 Johnson County

Johnson County wells are regulated by the Prairielands 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 Johnson County permit & regulations →

Frequently Asked Questions about Johnson County Wells

What aquifer is under Johnson County?
Johnson County wells primarily produce from the Trinity (Paluxy / Glen Rose / Hensell / Hosston) aquifer system (outcrop/shallow subcrop in western Johnson County; deep confined beneath Eagle Ford/Austin Chalk in eastern Johnson County). Woodbine (subsurface across central and eastern Johnson County) is a secondary target in parts of the county.
How deep are wells typically drilled in Johnson County?
Residential well depth in Johnson 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.
What water quality issues are common in Johnson County wells?
Hard water from dissolved calcium carbonate. Higher total dissolved solids (TDS, how mineral-heavy the water is) downdip (farther down where the layers tilt deeper) — eastern Johnson County, the deep Trinity, and the deep Woodbine. Iron and manganese, common where the Trinity reaches the surface (its outcrop) and in the Woodbine. Occasional hydrogen sulfide (a rotten-egg smell). Water testing after drilling — and periodically thereafter — is recommended for every private well in the county.
Does Johnson County require a permit to drill a water well?
Yes. You need a permit before drilling. The Prairielands GCD — the local district that permits wells — covers Ellis, Johnson, Hill, and Somervell counties. See the Johnson County permit and regulations page for the full process.
What's the main producing formation in Johnson County?
The primary producing formation is the Paluxy Sand (Trinity upper unit) — The Trinity layer most actively pumped in Johnson County (Prairielands GCD planning). It is at or near the surface in the west and lies deep beneath confining layers in the east. The rock is buff-to-tan sandstone. Most Johnson County residential wells are completed in this interval.

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