Abstract: A method of decomposing pyrogenic molecules in contaminated water which is disposed within a closed water container to produce, with surprising low energy requirements, pyrogen-free water.The method comprises placing water which is suspected to contain pyrogenic material (herein called "contaminated") into a sealable pressurizable container, sealing said container, heating said sealed container to a temperature of from about 180.degree. to about 230.degree. C, preferably about 200.degree. C, to create within the container a pressure sufficient, i.e., from about 15 to about 36 atmospheres, to prevent the formation of steam in said container while destroying all pyrogens in the container. After attaining the desired temperature for a brief period, that is, about 1-10 minutes, the heat is removed and the sealed container is cooled to room temperature in any suitable fashion and the water therein is ready for use or storage within the container, as the exigencies of circumstances dictate.