Dry siphon for linear drains prevents unpleasant odours from getting out of the sewers. The siphon is suitable for floor and wall models of Basso linear drains by Laveo. Simple method of installation will allow for installation of the siphon on user’s own in already housed drains, without causing any effect on water permeability. The siphon is fitted with a flap which opens automatically with sewage flowing, and allows for its free drainage. When water outflows completely the flap returns to the basic (closed) position and prevents unpleasant odours from getting out.