12 gallons per minute will make short work of unclogging pipes to 12" diameter. Over 12" possible depending on debris type. As a general guideline begin cleaning the pipe from the lowest (downhill) side. This allows loosened debris to be flushed out. Keep in mind that the most common nozzles direct all or most of the water back in the direction of the hose and the operator. Do not begin operation until the hose has been pushed into the pipe a safe distance. The JM-2512 has a hose vibrate feature that enables the hose to be more easily pushed through the pipe. Turns in the pipe may be easier to maneuver through after reducing pressure output. Cleaning the jet hose is done with the on board pressure washer wand/hose. Sometimes referred to as a hydro jetter or sewer jetter or drain jetter or tow behind jet or tow behind jetter