Jet interference in buckets and jet disturbance outside of buckets have been visually observed in a model runner for a 6-nozzle Pelton turbine. The visual observation has revealed that the jet from the first nozzle which entered into a bucket from the splitter and is now going to discharge out at the outcut of the bucket, is interfered by the jet from the second nozzle which has just entered into the outcut of the same bucket. Also, if the jet from the first nozzle which has discharged out at the outer brim of a bucket, is splashed radially outward and deflected by the nearest surfaces of deflector and/or nozzle to the outer surface of the second jet, severe jet disturbance occurs with the sharp efficiency deterioration.