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The Microbial Check Valve (MCV) is a reloadable flow-through canister containing iodinated ion exchange resin, which is used aboard the Shuttle Orbiter as a disinfectant to maintain water potability. The MCV exhibits a significant contact kill and imparts a biocidal residual I2 concentration to the effluent. MCVs in current use have nominal 30 day lives. MCVs baselined for Space Station Freedom will have 90 day lives, and will require replacement 120 times over 30 years. Means to extend MCV life are desirable to minimize resupply penalties. New technology has been developed for fully autonomous in situ regeneration of an expended MCV canister. The Regenerative Microbial Check Valve (RMCV) consists of an MCV, a packed bed of crystalline I2, a flow diverter valve, an in-line iodine monitor and a microcontroller. During regeneration, flow is directed first through the packed I2 bed and then into the MCV where the resin is replenished.

Approximately 50% of the water consumed by International Space Station crewmembers is water recovered from cabin humidity condensate. Condensing heat exchangers in the Russian Service Module (SM) and the United States On-Orbit Segment (USOS) are used to control cabin humidity levels. In the SM, humidity condensate flows directly from the heat exchanger to a water recovery system. In the USOS, a metal bellows tank located in the US Laboratory Module (LAB) collects and stores condensate, which is periodically off-loaded in about 20-liter batches to Contingency Water Containers (CWCs). The CWCs can then be transferred to the SM and connected to a Condensate Feed Unit that pumps the condensate from the CWCs into the water recovery system for processing. Samples of the condensate in the tank are collected during the off-loads and returned to Earth for analyses.

Iodine depletion in a simulated water storage tank and distribution system was examined to support a larger research program aimed at developing disinfection methods for spacecraft potable water systems. The main objective of this study was to determine the rate of iodine depletion with respect to the surface area of the stainless steel components contacting iodinated water. Two model configurations were tested. The first, representing a storage and distribution system, consisted of a stainless steel bellows tank, a coil of stainless steel tubing and valves to isolate the components. The second represented segments of a water distribution system and consisted of eight individual lengths of 21-6-9 stainless tubing similar to that used in the Shuttle Orbiter. The tubing has a relatively high and constant surface area to volume ratio (S/V) and the bellows tank a lower and variable S/V.

The Crew Health Care System (CHeCS) is responsible for providing environmental monitoring to protect crew health, including in-flight chemical water quality analysis. To meet this objective, Total Organic Carbon Analyzer (TOCA) Serial Number (SN) 1002 was launched to the International Space Station (ISS) in April of 2001 as part of the CHeCS hardware. Since that time it has been used to evaluate the quality of the potable water supplies consisting of reprocessed atmospheric condensate water, Shuttle-transferred water, and ground-supplied water. Potable water is available for crew use from the Service Module System for Regeneration of Water from Condensate (SRV-K) galley hot and warm ports and the Stored Potable Water System (SVO-ZV) port. Potable water samples are periodically collected from each of these ports for in-flight analysis with the TOCA.

Liquid Chromatography / Mass Spectrometry / Mass Spectrometry (LC/MS/MS) is a powerful technique for identifying unknown non-volatile organic compounds dissolved in liquids. One type of LC/MS/MS that is gaining popularity is quadrupole-time-of-flight (QqTOF) mass spectrometry. This technique is now in use at the Johnson Space Center for identification of unknown nonvolatile organics in water samples from the space program. An example of the successful identification of an unknown peak in U.S. Lab Condensate is reviewed in detail in this paper. Each step of the procedure is described in the identification of triethylene glycol mono-n-butyl ether (TGBE) as the unknown analyte. The advantages of time-of-flight instrumentation are demonstrated through this example as well as the strategy employed in using time-of-flight data to identify unknowns. The use of the instrument for quantitative analysis is also demonstrated.

Collapsible bladder tanks called Contingency Water Containers (CWCs) have been used to transfer water from the Shuttle to the Mir and the International Space Station (ISS). Because their use as potable water storage on the ISS is planned for years, efforts are underway to improve the containers, including the evaluation of new materials. Combitherm®, a multi-layer plastic film, is a material under evaluation for use as the CWC bag material. It consists of layers of linear low density polyethylene, ethylene-vinyl alcohol copolymer, nylon, and a solvent- free adhesive layer. Long term studies of the quality of water stored in Combitherm bladders indicate a gradual but steady increase in the total organic carbon value. This suggests a leaching or breakdown of an organic component of the Combitherm.

To satisfy a requirement to supply water to Mir station, a process for treating iodinated water on the Shuttle was developed and implemented. The treatment system consists of packed columns for removing iodine and a syringe-based injection system for adding ionic silver, the biocide used in Mir water. Technical and potable grade water is produced and transferred in batches using collapsible 44-liter contingency water containers (CWCs). Silver is added to the water via injection of a solution from preloaded syringes. Minerals are also added to water destined for drinking. During the previous four Shuttle-Mir docking missions a total of 2781 liters (735 gallons) of water produced by the Shuttle fuel cells was processed using this method and transferred to Mir. To verify the quality of the processed water, samples were collected during flight and returned for chemical analysis.

Potable water for the Shuttle orbiter is generated as a by-product of electricity production by the fuel cells. Water from the fuel cells flows through a Microbial Check Valve (MCV), which releases biocidal iodine into the water before it enters one of four storage tanks. Potable water is dispensed on-orbit at the rehydration unit of the galley. Due to crew health concerns, iodine removal hardware is installed in the chilled water inlet line to the galley to remove the iodine from the potable water before it is consumed by the crew. The Shuttle water system is sampled to ensure water quality is maintained during all operational phases from the disinfection of the ground servicing equipment through the completion of each mission. This paper describes and summarizes the Shuttle water quality requirements, the servicing of the Shuttle water system, the collection and analysis of Shuttle water samples, and the results of the analyses.