Device for cleaning a drain pipe or a pipe connected to the drain pipe in order to break down or reduce at least one blockage present in the drain pipe or in the pipe connected to the drain pipe by at least two successive waves of liquid escaping the device according to a laminar flow, said device comprising at least a duct with several distinct channels for the liquid, characterised in that the device comprises: - a reservoir comprising distinct separate compartments (C1,C2,C3,C4), the said reservoir having at least one connecting part adapted for connecting it to a water supply, said connecting part being advantageously associated to non return means, whereby each distinct compartment is provided with a distinct outlet opening; - an outlet adapted to be connected to a pipe selected from the group consisting of the drain pipe and the pipe connected to the drain pipe, said outlet being associated with a knife valve actuated by a valve actuating mechanism between a fully closed position and a fully open position; - the knife valve and the valve actuating mechanism; - the duct comprising the several distinct channels (11A,11B,11C, 11D) extending each between the outlet opening of each compartment (C1,C2,C3,C4) of the reservoir and an outlet opening (11A1,11B1,11C1,11D1) of each of the several distinct channels (11A, 11B, 11C, 11D) adjacent to the outlet of the device, said duct comprising a curved portion of 45 to about 90° so as to enable at least a gravity flow of liquid from a compartment of the reservoir towards the outlet of the device when the knife valve is in open position; whereby the knife valve actuated by the valve actuating mechanism is adapted to move from a fully closed position in which the knife valve closes the outlet openings of the various channels (11A,11B,11C, 11D) of the duct, up to a fully open position in which the said outlet openings (11A1,11B1,11C1,11D1) of the various channels (11A,11B,11C, 11D) of the duct are not closed by the knife valve, with intermediate positions for which one or more outlet openings of one or more channels (11A,11B,11C, 11D) are not closed by the knife valve, while one or more outlet openings (11A1,11B1,11C1,11D1) of one or more other channels (11A,11B,11C, 11D) are closed by the knife valve; in which the different channels (11A,11B,11C, 11D) are provided adjacent to their outlet opening with a honeycomb structure adapted for generating a laminar flow for the water flowing through said outlet opening (11A1,11B1,11C1,11D1) when not closed by the knife valve. - a reservoir comprising distinct separate compartments (C1,C2,C3,C4), the said reservoir having at least one connecting part adapted for connecting it to a water supply, said connecting part being advantageously associated to non return means, whereby each distinct compartment is provided with a distinct outlet opening; - an outlet adapted to be connected to a pipe selected from the group consisting of the drain pipe and the pipe connected to the drain pipe, said outlet being associated with a knife valve actuated by a valve actuating mechanism between a fully closed position and a fully open position; - the knife valve and the valve actuating mechanism; - the duct comprising the several distinct channels (11A,11B,11C, 11D) extending each between the outlet opening of each compartment (C1,C2,C3,C4) of the reservoir and an outlet opening (11A1,11B1,11C1,11D1) of each of the several distinct channels (11A, 11B, 11C, 11D) adjacent to the outlet of the device, said duct comprising a curved portion of 45 to about 90° so as to enable at least a gravity flow of liquid from a compartment of the reservoir towards the outlet of the device when the knife valve is in open position; whereby the knife valve actuated by the valve actuating mechanism is adapted to move from a fully closed position in which the knife valve closes the outlet openings of the various channels (11A,11B,11C, 11D) of the duct, up to a fully open position in which the said outlet openings (11A1,11B1,11C1,11D1) of the various channels (11A,11B,11C, 11D) of the duct are not closed by the knife valve, with intermediate positions for which one or more outlet openings of one or more channels (11A,11B,11C, 11D) are not closed by the knife valve, while one or more outlet openings (11A1,11B1,11C1,11D1) of one or more other channels (11A,11B,11C, 11D) are closed by the knife valve; in which the different channels (11A,11B,11C, 11D) are provided adjacent to their outlet opening with a honeycomb structure adapted for generating a laminar flow for the water flowing through said outlet opening (11A1,11B1,11C1,11D1) when not closed by the knife valve.