At McChord AFB outside of Tacoma, Washington, the C-17A Globemaster IIIs of the 446th Airlift Wing are washed regularly in two of three purpose-built hangars that have sloped floors with three trenches to collect the water used. Pressure washing a C-17A takes eight workers about 12 hours and 500 to 700 gallons of water. Each worker, equipped with a three-foot long wash wand, wears a face shield and apron to protect against the solvents used.
The workers at McChord AFB also fill requests to clean C-130s, KC-135s and even the Army's CH-47s. In general, wheel wells get the dirtiest.
Source: Air & Space Smithsonian, November 2008. "Then & Now", p74.