Freeze Expansion Surface Profile

A fluid reservoir, comprising:

• a primary holding tank defining said fluid reservoir;
• a volume expansion feature incorporated into at least one wall structure of said fluid reservoir;
• said volume expansion feature having a central recess and a plurality of channels extending therefrom;
• said central recess and said channels positioned at least in part in a recessed surface profile, said recessed surface profile being reversibly moveable from a first inwardly directed configuration to define a first volume of said fluid reservoir, to a second outwardly directed configuration to define a second volume of said fluid reservoir, said second volume being greater than said first volume;
• wherein said central recess and said channels are configured to impart an inward bias to maintain said recessed surface profile in said first inwardly directed configuration under standard loading of said fluid reservoir, and wherein upon increased pressure within said fluid reservoir, said recessed surface profile extends to said second outwardly directed configuration.