Abstract: The gas distributor is provided for aeration of water, particularly for the supply of oxygen in biological waste water treatment plants, but also for aeration of lakes whose oxygen content has been decreased due to the supply of pollutants. The gas distributor includes a base plate (2), over which a diaphragm (3) with fine openings (16) is stretched. Air, oxygen or other gases with such a volume per time unit are pumped between the base plate and the diaphragm (3) so that the diaphragm (3) expands slightly. Excessive expansion of the diaphragm is prevented by an upper grating part that extends over the total diaphragm (3). The diaphragm (3) is connected to the base plate (2) via a fastening device made of three members (6-8) that engage, for example, a recess (11) that has a dovetail-shaped cross-section. The diaphragms (3) are clamped to the base plate by means of a snap closure. The present embodiment uses no adhesive that could damage the diaphragm (3).