A valve system fluidly connectable to a pump system comprising at least one pump assembly being fluidly connectable to a pipe, wherein the valve system comprises at least one valve comprising a pipe section of the pipe, wherein the pipe section defines a primary flow direction, wherein the at least one valve further comprises a valve opening in the pipe section, a valve seat and a valve body, wherein the valve opening, the valve seat and the valve body define a common valve axis extending transversely to the primary flow direction, wherein the at least one valve further comprises an operating element, wherein the at least one valve further comprises a valve control shaft extending along the valve axis and operatively connecting the operating element and the valve body, wherein the valve control shaft comprises a first stop surface facing along the valve axis towards the valve opening, the operating element being arranged at the pipe section diametrically opposite from the valve opening, wherein the operating element is configured to control the valve body for selectively operating in a check-valve mode, in which the valve body is movable along the valve axis to open the valve opening upon a fluid flow from the valve opening towards the valve body, characterized in that the operating element is configured to control the valve body for selectively operating in a shut off-valve mode, in which the valve body is fixed against the valve seat by the first stop surface pushing the valve body against the valve seat to close the valve opening for any fluid flow direction, wherein the at least one valve further comprises a pump connection being connectable to the at least one pump assembly, wherein the valve seat is an integral part of the pump connection. wherein the valve system comprises at least one valve comprising a pipe section of the pipe, wherein the pipe section defines a primary flow direction, wherein the at least one valve further comprises a valve opening in the pipe section, a valve seat and a valve body, wherein the valve opening, the valve seat and the valve body define a common valve axis extending transversely to the primary flow direction, wherein the at least one valve further comprises an operating element, wherein the at least one valve further comprises a valve control shaft extending along the valve axis and operatively connecting the operating element and the valve body, wherein the valve control shaft comprises a first stop surface facing along the valve axis towards the valve opening, the operating element being arranged at the pipe section diametrically opposite from the valve opening, wherein the operating element is configured to control the valve body for selectively operating in a check-valve mode, in which the valve body is movable along the valve axis to open the valve opening upon a fluid flow from the valve opening towards the valve body, characterized in that the operating element is configured to control the valve body for selectively operating in a shut off-valve mode, in which the valve body is fixed against the valve seat by the first stop surface pushing the valve body against the valve seat to close the valve opening for any fluid flow direction, wherein the at least one valve further comprises a pump connection being connectable to the at least one pump assembly, wherein the valve seat is an integral part of the pump connection.