Liquid storage system

Disclosed is a liquid storage system comprising: an outer tank (16) (e.g. an aircraft fuel tank) for containing a liquid (e.g. aircraft fuel), said outer tank (16) enclosing a liquid storage space (14); an inner tank (18a, 18b) located within the outer tank (16) and enclosing the liquid storage space (14); and spacing means (20a, 20b) associated with the outer tank (16) and the inner tank (18a, 18b) for maintaining said tanks in a spaced apart relationship; wherein the spacing means (20a, 20b) are deformable such that, on application of a force to the inner tank (18a, 18b), at least part of the inner tank (18a, 18b) moves relative to the outer tank (16).