The invention provides a dosing system for an inhalation device, comprising a filling chamber (10); a reservoir chamber (31) which supplies liquid (3) to an aerosol generator (301); and a plunger (20) which includes an overflow chamber (25) and which is pivotable about a hinge (50). The filling chamber has an inner wall (12) which is higher on the side adjacent to the hinge than on the opposite side. When the filling chamber is filled with liquid and the plunger is pivoted into the filling chamber, part of the liquid is displaced over the lower side (17) of the inner wall into the reservoir chamber and some or all of the remaining liquid is displaced into the overflow chamber. The invention also provides an inhalation device comprising the dosing system and a method for dosing liquid to the inhalation device.