Water is one of the most crucial provisions that astronauts need to live and work in space, whether orbiting Earth, working at a lunar base or traveling to Mars. For long-duration human missions, drinking water can come from a variety of sources including treated humidity condensate, urine, hygiene water or makeup sources (e.g., water brought up from the ground or obtained through fuel cells). There are concerns that reclaimed water may contain trace toxic metals and/or the recovery and treatment processes may result in corrosion and leaching of metals during storage (methods for spacecraft guidelines). As a result, these systems must be continually monitored to ensure the health of the crew. The overall objective of the proposed program is to develop a field compatible electrochemical sensor for the identification and measurement of trace heavy metals in the water. Phase I will investigate the optimal design configuration, electrode configuration, and operating conditions, which will enhance sensitivity and enable reproducible detection of the dissolved compounds such as cadmium, nickel, silver and zinc in water. The proposed process can be carried out rapidly without the use of dangerous chemicals and will fulfill NASA's need.