A hot water tank comprising a sleeve, a removable top lid, at least one changeable water holding compartment adapted to be stacked vertically within the sleeve, stacked compartments being connected by a connecting pipe and at least one heating means provided with one of the compartments. The changeable compartments are configured to be removable from the sleeve upon removal of the top lid in case of failure and the space between the sleeve and the changeable compartments is adapted to hold the contents of the compartments during a leak.