 Freshly cut ends of pipe segments are carefully deburred to remove projecting slivers of material which may snag debris (such as hair or fibers) which can build up to cause blockages.This internal smoothness also makes it easier to "snake out" or "rod out" a clogged pipe with a plumber's snake.Underground piping systems for landscaping drainage or the disposal of stormwater or groundwater also use low-pressure gravity flow, so fittings for these systems resemble larger-scale DWV fittings.