Potable- and hygiene-quality water will be supplied to crews on the International Space Station through the recovery and purification of spacecraft wastewaters, including humidity condensate, urine, and wash water. Contaminants released into the cabin air from human metabolism, hardware offgassing, flight experiments, and routine operations will be present in spacecraft humidity condensate; normal constituents of urine and bathing water will be present in urine and untreated wash water. This report describes results from detailed analyses of Mir reclaimed potable water, ground-supplied water, and humidity condensate. These results are being used to develop and test water recycling and monitoring systems for the International Space Station (ISS); to evaluate the efficiency of the Mir water processors; and to determine the potability of the recycled water on board.Only 6% (by weight) or less of the organic constituents in reclaimed water collected during Mir-18, Mir-19, and Mir-20 could be identified by using current analytical techniques. Nonetheless, the reclaimed water met all of the Russian Space Agency (RSA) standards and all of the NASA standards except those for total organic carbon (TOC), total phenols, and turbidity. The water also met all U.S. Environmental Protection Agency (EPA) drinking-water standards except for methylene chloride. Ground-supplied water samples also met all of the RSA and NASA standards except for NASA's TOC, turbidity, and ammonium requirements. Some of these samples also exceeded the EPA standards for methylene chloride and chloroform.