Device for collecting liquid pet waste comprising a first liquid waste collecting container (2) covered on the top by a lid (4). Lid (4) is removable and is provided with a plurality of through holes (6) for the liquid waste. Also, first container (2) of device (1) contains organic matter (8) that is compostable, and suitable for being impregnated by said liquid pet waste. The invention also relates to a method for producing natural fertiliser in a collective use urban environment via device (1).
