The present invention relates to pressure tank used for storage of pressurized mediums as well as for processes with pressurized mediums. Pressure tank comprising a shell, closed with tank head/bottom (2, 3 or 3A), at least one tank head/bottom is flat, equipped with connections (6) and with at least one inspection manhole (7) is characterized in that below flat tank bottom (2) at least one reinforced concrete slab (4) connected to a shell (1) using fixing elements (5) and slab (4) is arranged.
