The present invention relates to a method for treating the blood of a patient, comprising removing water from the blood of patients at a settable water removal rate, wherein the position of the patient is determined and the water removal rate is set, controlled, and/or regulated depending on the determined position of the patient. The invention further relates to an apparatus for treating the blood of a patient, comprising a blood treatment device for removing water from the blood of the patient at a settable water removal rate, wherein position-determining means for determining the position of the patient, wherein the water removal rate is settable, regulatable, and/or controllable depending on the determined position of the patient.