How Deep Are Wells in the Texas Hill Country?

Most Hill Country wells tap one of four formations: the Trinity, the Edwards, the Ellenburger-San Saba, and the Hickory. Each behaves very differently.

The Trinity is the workhorse — it underlies most of Kendall, Comal, Hays, Blanco, Travis, Burnet, and parts of Gillespie counties. Residential wells into the Trinity typically run 300–700 ft. Yields are reliable but not enormous, and water is hard.

The Edwards aquifer is shallower, faster-recharging, and karstic — heavily fractured limestone. It is mostly tapped where it outcrops along the Balcones escarpment near San Antonio and Austin. Wells can be very productive, but they are also very drought-sensitive.

The Hickory aquifer is the deepest reliable producer in the western Hill Country — Mason, Llano, San Saba, and parts of Gillespie. Hickory wells often run 500–800 ft, sometimes deeper. Water is excellent in volume but commonly carries elevated iron, manganese, and (in some areas) radium that needs treatment.

The Ellenburger-San Saba sits beneath the Hickory in the Llano Uplift area and is occasionally tapped where the Hickory does not produce.

Boerne (Kendall County): Most residential wells fall between 350 and 650 ft into the Trinity. Properties closer to Comfort or out toward Cordillera Ranch can run deeper. Karst features mean two neighbors a quarter mile apart can hit water at very different depths.

Fredericksburg (Gillespie County): Residential wells here typically run 500–800 ft into the Hickory aquifer because the shallow Trinity in this area is thin and unreliable. Properties closer to Stonewall sometimes hit usable water at 350–500 ft.

Dripping Springs (Hays County): The most variable area in the Hill Country. The Trinity contact zone runs through this growth corridor, so depths swing from 300 to 900 ft over short distances. Bell Springs Road, Fitzhugh Road, and the U.S. 290 corridor are all unpredictable without local driller data.

Marble Falls (Burnet County): Generally 300–650 ft into the Trinity, with shallower wells common on the lake side and deeper wells common as you head west toward the Llano Uplift.

Burnet County overall: 300–800 ft depending on which side of the Llano Uplift you sit on. Eastern Burnet County is mostly Trinity. Western and southern areas tap Ellenburger and Hickory.

Blanco County: 350–700 ft into the Trinity is the norm, with ranch wells often a bit deeper for higher yield.

Kerrville and Kerr County: 200–600 ft, mostly Trinity, with some shallow Edwards wells along the Guadalupe River corridor.

No reputable Texas water well driller will quote a guaranteed depth before drilling. The reason is geological: Hill Country formations are fractured and faulted at small scales, and even an excellent regional report only narrows the range.

What a good driller will do is pull every TDLR-registered driller report within a half-mile radius of your property — usually 5 to 30 nearby wells — and quote a depth range based on the actual recorded results in that section. That gives you a realistic budget envelope, not a single number.

Drilling cost in the Hill Country is typically billed per foot for the actual drilling work, plus fixed costs for casing, mobilization, and the pump system. Per-foot rates in 2026 commonly fall in the $35–$60 range depending on formation hardness and casing requirements.

A 400-ft Trinity well in Boerne is usually a meaningfully smaller project than an 800-ft Hickory well in Fredericksburg, even though both produce a working residential water supply. That is the single biggest reason cost varies so much across the region.

For a deeper breakdown, see our article on water well cost in Texas.