A portable decontamination system includes a preassembled shelter, convertible between a stowed configuration and a deployed configuration, and a fluid delivery system integral with the shelter. In the stowed configuration the shelter encloses a negligible volume. In the deployed configuration the shelter comprises a plurality of side walls, a plurality of end walls, and a roof. The walls and the roof define a central space. The fluid delivery system is configured to convey decontamination fluid into the shelter and to distribute decontamination fluid throughout at least a portion of the central space.