What Is Produced Water?

Here’s what you need to know about wastewater from oil and gas drilling operations.

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Farmers in Kern County's Cawelo Water District have long struggled to irrigate crops with dwindling groundwater supplies and surface water allocations. For decades, the district has supplemented that water with oil field wastewater, known as "produced water." Credit: Liza Gross

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“Produced water” is water that returns to the surface as wastewater during oil and gas production.

The water typically contains hydrocarbons from the deposit as well as naturally occurring toxic substances like arsenic and radium, salts and chemical additives injected into the well to facilitate extraction. These additives include carcinogens and numerous other toxic substances that have the potential to harm human health and contaminate the environment. The content and toxicity of produced water vary considerably, depending on the geology of the petroleum deposit. 

Produced water is the largest waste stream from fossil fuel extraction. Methods to extract fuels from aging oilfields and unconventional, or fracked, shale formations typically require far more water than conventional operations. 

Oil and gas operators recycle some of their wastewater to extract more fuels but some operations require freshwater. Produced water is generated wherever oil and gas is extracted, with Texas, Illinois, California and Oklahoma, leading other oil and gas producing states such as Colorado and Pennsylvania.

Wastewater that isn’t reused is typically injected underground, raising concerns for nearby landowners in Texas. In California, a local water board allows oil companies to sell their wastewater to farmers for irrigation, claiming the practice is safe. But an Inside Climate News investigation found that the board relied on scant evidence produced by an oil industry consultant and never reviewed long-term impacts on plants, soil, crops and wildlife. 

Why it Matters

  • Oil and gas companies use massive amounts of water in drought-prone areas to extract the same fossil fuels that exacerbate extreme weather.
  • Companies are looking for ways to recycle produced water to conserve freshwater sources, but some worry the practice will prolong reliance on fossil fuels.
  • Lax oversight of produced water disposal endangers the health of nearby communities and the environment.

By the Numbers

  • 60 percent of the hundreds of chemicals used in oil operations deemed most likely to pose a health risk lack both toxicity information and approved testing methods. 
  • 11 percent of Kern County, California’s irrigated farmland is irrigated with produced water.
  • 60 billion barrels of produced water have been disposed of in the Permian Basin in West Texas, about half since 2010. 

Dive Deeper

Produced Water in California

A decades-long drought in California left water managers in the Central Valley, the state’s most productive agricultural region, desperate for water. That led them to expand reliance on produced water as an alternative water source for irrigation. 

The Central Valley Regional Water Quality Control Board assured critics that its review of studies commissioned as part of an extensive Food Safety Project identified no increased health risks from eating crops grown with the wastewater. The board acknowledged that it did not study the long-term consequences of intentionally applying produced water on agricultural fields, including how it might affect crops and soil or whether toxic chemicals in the wastewater could accumulate over time in the nuts, oranges and grapes that are sent around the world. Nor did the board consider the ecological risks of the practice in a county where at least 20 threatened or endangered species live within about a mile of an oil field.

California does not allow produced water generated from fracking for use as irrigation water. But an Inside Climate News analysis found that there’s little difference in chemical profiles between produced water from fracking and conventional operations, like those in Kern County. Both harbor many of the same highly toxic chemicals and likely pose similar risks. 

Dive deeper into produced water with California reporter Liza Gross’s Izzy-award-winning investigation, Something in the Water.

Produced Water in Texas

Texas generates more produced water than any other state, and the oilfields of the Permian Basin alone generate more produced water than all other U.S. shale plays combined—about half a billion gallons per day. The high water volume results in part from the region’s high level of oil production and in part from the naturally large amount of fossil water in the oil-producing Permian shales, where wells can surface more than five barrels of mucky water for every barrel of oil. 

Produced water in the Permian is naturally much saltier than in California, making it more costly to treat and reuse. So far, it hasn’t been applied to crops, although state-funded studies are exploring that possibility as Texas struggles to manage the immense waste stream that has grown in step with soaring Permian oil production. 

A small but growing portion of produced water is reused for hydraulic fracturing. The vast majority is injected at high pressure into loosely regulated disposal wells. An intensifying spate of West Texas earthquakes has been linked to the massive injection volumes, and has raised concerns that produced water disposal could threaten freshwater aquifers. 

In the history of the Permian Basin, some 60 billion barrels of produced water have been disposed of, about half since 2010. Several hundred billion more remain to be dealt with as Permian oil production continues.

Produced Water in Pennsylvania

Most produced water in Pennsylvania is recycled and reused to drill new fracking wells. But not all of it. 

The remaining toxic and radioactive wastewater is stored in injection disposal wells. But Pennsylvania only has 12 active injection disposal wells for wastewater that drillers can’t recycle. Ohio had 228 in 2021.

Because of that, three-quarters of Pennsylvania wastewater destined for wells is trucked to Ohio, where both environmental activists and oil companies are demanding stricter regulation. They worry that leaked waste could contaminate clean water sources and productive oil wells.

“It is toxic,” Radisav Vidic, an environmental engineer at the University of Pittsburgh, said of the wastewater. “I wouldn’t drink it or spread it. I wouldn’t use it for irrigation or livestock. I wouldn’t do anything with it, because it’s bad.”

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