A fluid management system for use in water electrolysis systems for filtering the system water and recombining hydrogen and oxygen. The fluid management system includes a phase separation tank having a filter containing a catalyzed ion exchange resin. Hydrogen/water mixture and an oxygen/water mixture are introduced into the resin where hydrogen is recombined with oxygen to produce recovered water. Trace contaminant ions and particles are removed from the water by the ion exchange resin and the filter.