A plastic tank for liquids formed as a rectangular-solid or cubic container has four sidewalls, an upper base with a filling socket, a lower base, and an outlet socket, the outlet socket being formed on the lower section of a sidewall for connection to a tapping valve. The upper corner regions between the sidewalls and the upper base of the container and/or the lower corner regions between the sidewalls and the lower base of the container have at least one indentation or projection each.