A fluid-tight foot support system (450), comprising: a foot support bladder (102) for supporting at least a portion of a wearer's foot; a pump (110); a first fluid transfer line (410) extending between the foot support bladder (102) and the pump (110); a first valve (114) allowing fluid transmission from the foot support bladder (102) to the pump (110) via the first fluid transfer line (410) but not allowing fluid transmission from the pump (110) to the foot support bladder (102) via the first fluid transfer line (410); a fluid reservoir (104); a second fluid transfer line (412) extending between the pump (110) and the fluid reservoir (104); a second valve (118) allowing fluid transmission from the pump (110) to the fluid reservoir (104) via the second fluid transfer line (412) but not allowing fluid transmission from the fluid reservoir (104) to the pump (110) via the second fluid transfer line (412); a third fluid transfer line (414) extending between the first fluid transfer line (410) and the second fluid transfer line (412); a fourth fluid transfer line (416) extending between the first fluid transfer line (410) and the second fluid transfer line (412), wherein the third fluid transfer line (414) is separate from the fourth fluid transfer line (416); and a fluid flow direction regulating system for moving fluid: (a) in a first path from the foot support bladder (102) to the fluid reservoir (104) or (b) in a second path from the fluid reservoir (104) to the foot support bladder (102), wherein when fluid moves in both the first path and the second path, the fluid moves in a direction from the first fluid transfer line (410), through the pump (110), to the second fluid transfer line (412).