Tim Carter explains why vent pipes are important and how a vent pipe works. These are excellent videos to watch if you need to learn how to prevent clogging in vent piping. If you notice a gurgle when flushing the toilet, it might be an indication that the vent pipe is clogged. Get up on the roof and put a garden hose down the pipe and turn on the water. Be sure to have someone inside checking for any leaks. The water from the hose hopefully will flush out the blockage and your gurgle will disappear.