A self-propelled effluent distributor (8), the distributor including a chassis (13)； an outlet for a liquid (9), wherein the outlet is mounted to the chassis； a drive mechanism (17) including a housing (19), wherein the housing has an inlet port (19a) for the liquid and an outlet port (19b) for the liquid, wherein an exterior surface of the inlet port is configured to mate with a conduit to a supply of liquid, and wherein the housing of the drive mechanism includes a drive wheel with a plurality of paddles, the drive wheel mounted such that the paddles face the inlet port； a conduit (10 a, b, c) for the liquid, wherein the conduit has a first end and a second end, and wherein the first end is linked to the outlet and the second end is linked to the outlet port of the housing of the drive mechanism, characterised in that the distributor includes a mechanism to operate a ball valve for stopping the flow of liquid at the end of the run.
