Compatibility Study of Silver Biocide in Drinking Water with Candidate Metals for the Crew Exploration Vehicle Potable Water System

The stability of silver biocide, used to keep drinking water on the CEV potable water disinfected, is unknown as the system design is still in progress. Silver biocide in water can deplete rapidly when exposed to various metal surfaces. Additionally, silver depletion rates may be affected by the surface-area-to-volume (SA/V) ratios in the water system. Therefore, to facilitate the CEV water system design, it would be advantageous to know the biocide depletion rates in water exposed to the surfaces of these candidate metals at various SA/V ratios. Certain surface treatments can be employed to reduce the depletion rates of silver compared to the base metal. The purposes of this work are to determine the compatibility of specific spaceflight-certified metals that should be used in the design of the CEV potable water system with silver biocide, as well as understand the effect of surface area to volume ratios of metals used in the construction of the potable water system on silver concentration.