Abstract: A water heater adapted to avoid peak temperatures of delivered water comprises a plate heat exchanger (1) connected to a storage container (2) provided with interior reinforcing means (9-11. FIG. 1; 13-13′″. FIGS. 5-18) connecting opposite parts of the outer wall (2′) of the container (2). Even provided with a thin storage container wall this makes it possible to use a box shaped water heater design without risk of deformations due to variations in the water pressure. The reinforcing means may consist of stacked interconnected plates (13-13′″). e.g. having the same form and size as plates (12-12′″) used in a plate heat exchanger connected to the container (2).