Water is injected before the high pressure compressor to cool the turbine allowing increased horse power. Water is also injected into the combustion chamber to control NOx emissions.

Water entering the engine must be extremely clean and free of dissolved minerals, i.e. calcium, which are normally present in tap water. All water used in the engine goes through reverse osmosis (passes through a membrane which allows the water to flow through, but not most minerals).

The water next undergoes demineralization. The water passes through resins and the positive and negatively charged minerals are attracted to and attach to the resin beads. This demineralized water is held in storage until needed. When called upon to be used, the water again goes through the demineralization process to be sure it hasn't picked up any contaminants from the pipes and tanks.