What decides the depth, and the price
A well costs what it costs mostly because of how deep the driller has to go to hit good water, and that is set by where your land sits over the aquifer, not by anything you pick. Two ranches a few miles apart can need very different depths. That is why an honest well driller will not throw out a firm number over the phone for a brand-new well; they need to know the area, look at nearby well logs, and sometimes test. Be wary of a too-confident quote on ground nobody has looked at.
The aquifer under South Texas
Most of this region draws from the Gulf Coast aquifer system, and how deep and how clean the water is varies across ranch country. Closer to the coast there can be salt intrusion that makes shallow water brackish, so sometimes the right answer is drilling deeper to a better zone rather than settling for the first water you hit. A driller who works this area knows the local zones and will aim for water you can actually use, which is the whole point.
Doing it by the book
In Texas, water well drillers are licensed and a well report gets filed with the state, and you want both. The report documents how deep the well is, what the driller hit, and how it was completed, and it protects you if you ever sell the land or have a problem. Ask that the driller is licensed and that you get a copy of the state well report, along with the pump specs. This is the paperwork that turns a hole in the ground into a documented asset.
- Depth is set by the aquifer under your land, not by choice
- Water quality out here varies a lot, so testing is part of the job
- A registered driller and a state well report protect you later
Texas requires drillers and pump installers to carry state licensing under separate occupational codes covering each trade. Local groundwater district rules can add their own requirements for spacing, well logs, completion, and shutting a well down properly.