Abstract: A membrane pouch, for rehydrating sterile intravenous and other solutions for non-sterilized fresh water, has a double bag construction. An inner bag made of semipermeable membrane material holds the sterile solutes to be rehydrated. The membrane material is permeable by water but impermeable to contaminants and a large molecular weight solute contained in the bag. An outer waterproof bag encloses the membrane bag and serves as a container for fresh water. Each bag has a sealable valve for providing access to the interior thereof. A high molecular weight dye located in the outer bag provides a visible indication of the existence of any discontinuity in the membrane bag. A low molecular weight, water soluble, non-toxic substance having a high osmotic pressure can be placed inside the membrane bag to accelerate the osmotic transfer of sterile water from the outer bag into the inner membrane bag.