A process for purifying crude fluoromethyl 1,1,1,3,3,3-hexafluoroisopropyl ether (sevoflurane). The crude sevoflurane is repeatedly washed with water under conditions and for a time sufficient to reduce the level of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) to no more than 200 ppm or no more than 100 ppm.