As the water-intensive practice of fracking continues to spread, the amount of wastewater being buried in disposal wells around Texas has skyrocketed. But the wells bring concerns about truck traffic and the possibility of groundwater contamination.

In drilling regions like the Permian Basin, where the water needs of fracking have run up against a historic drought, drillers are increasingly turning to brackish groundwater previously thought too expensive to use.

Most fracking operations use several million gallons of water. But with water increasingly scarce and costly around Texas, a few companies have begun using alternative liquids, such as propane. Experts say the technology still has far to go.

In Pennsylvania's Marcellus Shale, natural gas companies recycle water as a matter of course. But recycling is only getting started in the Texas oilfields because using freshwater for hydraulic fracturing is cheap.

The amount of water used in hydraulic fracturing has stirred concerns around Texas, especially as the drought wears on. Aware that they are under the spotlight, drillers are testing out recycling and other water-saving techniques.