Two months after the BP oil spill, it may be easy to hear the words "water contamination" and "drilling" and immediately think "Gulf Coast."
But one filmmaker says there's another water source at risk -- and this one is in our own backyards.
In his new film, "Gasland," filmmaker Josh Fox spotlights the practice of hydraulic fracturing, or hydrofracking, a process that extracts natural gas from rock formations.
He started his film after a gas company offered him nearly $100,000 for the rights to drill for natural gas on his property in the Delaware River Basin, along the New York-Pennsylvania border.
Instead of accepting, Fox began investigating.
His documentary premiered on HBO on Monday night and highlighted what Fox claims are the direct results of hydraulic fracturing: water contamination, well failures and health problems for people living near the wells.
HBO will be replaying the documentary later this month and next month.
The film explains hydraulic fracturing as a "mini earthquake." Gas companies insert a horizontal pipe several thousand feet below the ground and blast a "fracking fluid" to break up the rock and release natural gas.
To tell the story, Fox -- whose property sits on the Marcellus Shale Field, a rock formation often called the Saudi Arabia of natural gas -- dubbed himself a "natural gas drilling detective." He traveled across the country with a camera, interviewing landowners who have entered into contracts with natural gas companies.
The film has generated both acclaim and controversy. "Gasland" won the Special Jury Prize at the 2010 Sundance Film Festival. Variety called it "one of the most effective and expressive environmental films of recent years."
The New York Times was more critical: "Mr. Fox shows a general preference for vivid images ... over the more mundane crossing the t's and dotting the i's of investigative journalism," wrote the reviewer.
Cabot Oil & Gas is one of the companies featured in "Gasland." In response to questions from ABCNews.com, spokesman George Stark wrote, "'Gasland' is long on rhetoric and emotion, yet short on accurate facts and information."
Other companies also have spoken out against the film's claims, specifically regarding the characterization that the chemicals in the fracking fluid are a secret.
Fox narrates, "Because of the exemptions, fracking chemicals are considered proprietary, like the special sauce for a Big Mac or the secret formula for Coca-Cola."
Range Resources, an oil and gas company, called that claim "100 percent false," Matt Pitzarella, spokesman for Range, told ABCNews.com. He added that gas companies are required to submit a material safety data sheet to the Department of Environmental Protection every time they frack a new well.
The Pennsylvania Department of Environmental Protection lists the chemicals, such as hydrochloric acid, methanol and glutaraldehyde, on its Web site.
A spokesperson from Energy In Depth, a nonprofit group created by the Independent Petroleum Association of America, drafted a response called "'Gasland' Debunked": "The entire universe of additives used in the fracturing process is known to the public ... The Occupational Safety and Health Administration mandates this information be kept at every wellsite."
Fox responded, "The actual chemical names are available to the public, but we only know the actual chemical composition of about 50 percent of the products. And the ones we do know are nasty."