Water at ambient temperature is a notoriously poor solvent for most organic pollutants such as polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and most pesticides. Supercritical water (temperature >374°C, pressure >221 atm) is extremely corrosive. The EERC has demonstrated that the polarity of water can be controlled over a wide range of temperatures by simply heating it under enough pressure (a few atmospheres) to maintain the liquid state. With temperature control up to 350°C, water can perform very selective extractions of polar (at lower temperatures), moderately polar, and nonpolar (at higher temperatures) organic pollutants from contaminated soils and waste sludges. Complete removal of a wide variety of organic pollutants from real-world samples has been demonstrated with only a few minutes of subcritical water extraction.

Subcritical water can also be used to destroy reactive organic pollutants such as the explosives in TNT, RDX, HMX, many pesticides, and PCBs. Soils treated in this manner are fertile and have greatly reduced toxicity.

The EERC has constructed several laboratory-scale systems and one pilot-scale (8-L) unit to perform subcritical water extractions and reactions. Removal of high concentrations of carcinogenic PAHs and the rapid destruction of several pesticides and explosives have been demonstrated with this system.