Groundwater
Dallas County Sits Over the Trinity Aquifer
The Trinity Aquifer runs under Dallas County and much of North Texas, but most county residents rely on surface water, not wells.
The Trinity Aquifer is a large underground water source beneath Dallas County and 60 other Texas counties. In North Texas, the freshwater layer can be around 600 feet thick. But water levels near the IH-35 corridor have dropped a lot over the years from heavy city pumping.
Most Dallas County residents get water from city systems fed by surface reservoirs, not private wells. If you own rural land with a private well, the aquifer's water quality can range from fresh to slightly salty depending on how deep the well goes. Contact the Texas Water Development Board at twdb.texas.gov for groundwater data and maps.
Source to confirm: TWDB – Trinity Aquifer