First appears in: The Metal Wood
Water Processing THREE is a specific area in the Under that serves as a "Navy tent area" and the primary living quarters for the killgirls of Her Majesty's Navy. It is described as a place where "ever-present overhead lights... shone down on it from outside, giving it a blueish sort of glow" and was filled with a "multicolored collection of canvas and vinyl" tents. For characters like Megan, the area "felt like home," despite being a world of "rumbling machines" and the constant heat of the processing equipment.
Living in this area is considered a relative luxury because it provides access to "rationed three-minute shower[s]," a privilege not afforded to all underkids. The location is the site of personal intimacy and later betrayal for Megan and Beam; it is where they share their shared tent until Queen orders Megan’s expulsion following the destruction of the whiproom. When Megan later returns to search for her girlfriend, she finds the tent "gone" and herself "ordered to leave" by Queen's command.