ISS Potable Water Sampling and Chemical Analysis: Expeditions 6 & 7

Ever since the first crew arrived at the International Space Station (ISS), archival potable water samples have been collected and returned to the ground for detailed chemical analysis in order to verify that the water supplies onboard are suitable for crew consumption. The Columbia tragedy, unfortunately, has had a dramatic impact on continued ISS operations. A major portion of the ISS water supply had previously consisted of Shuttle-transferred water. The other two remaining sources of potable water, i.e., reclaimed humidity condensate and Russian-launched ground water, are together insufficient to maintain 3-person crews. The Expedition 7 crew launched in April of 2003 was, therefore, reduced from three to two persons. Without the Shuttle, resupply of ISS crews and supplies is dependent entirely on Russian launch vehicles (Soyuz and Progress) with severely limited up and down mass. As a result, the chemical archival sample collection frequency has been temporarily reduced from monthly to quarterly, with a sample volume of only 250 instead of 750 milliliters. This smaller sample volume has necessitated reductions in the number of analyses that can be performed, including turbidity, total dissolved solids, dissolved silver, total iodine, pH, and/or conductivity. This paper reports the analytical results for archival samples of reclaimed condensate and ground- supplied potable water collected during Expeditions 6 and 7 and compares them to ISS water quality standards.