Four-layered material for a flexible fluid reservoir

A fluid reservoir comprising:

• a first sheet and a second sheet welded together around perimeter edges thereof to form a weld seam except along an open top, wherein an internal space for fluid storage is defined between the first and second sheets;
• wherein the open top comprises a re-closable opening defined between the first and second sheets and through which fluid is transferred into and/or out of the internal space;
• wherein, adjacent the open top and extending towards a bottom of the fluid reservoir, each of the first sheet and the second sheet comprises a four-layer insulated wall, the four-layer insulated wall comprising:
• an interior layer;
• an exterior layer;
• a metallic film layer;
• and
• an insulation layer;
• wherein the interior layer and the exterior layer are welded to each other within the weld seam with the metallic film layer and the insulation layer disposed between the interior layer and the exterior layer and spaced apart from the weld seam, and
• wherein the four-layer insulated wall comprises an exit port having a passage extending from the internal space for fluid storage to an outer surface of the exterior layer, the exit port being configured to connect to a fluid transfer tube.