When the sink will not drain, and the drain line isnt blocked, it may need to look up towards the ventilation system. When a vent becomes clogged, it shows up within the home as everything from the phantom flushing at the toilet to sinks that simply wont drain properly.The following can collect inside a vent:Dead birds or birds nests.Bodies of dead rodents.Leaves, trash, and other rubbish, which are sometimes almost impossible to removeTennis balls etc.Clearing blockages in the vent pipes can be a real hassle, however you know what, you can take some preventive steps. Sadly the best place to begin the clearing of vent pipe work is from the roof. Working up on the roof can be a dangerous task, to say the least. So, you may want to have this job done by someone who has experience working up high. Dagenham Plumbers can carry out this work. If you feel confident about performing the work yourself, be sure that the roof is dry, wear rubber-soled shoes, and use a safety harness to prevent yourself from falling off the roof if you slip.You will need a torch, a?plumbers?snake and a rubber hose. Use the torch to shine a bright light down the vent pipe to look for leaves, or other debris you may be able to remove. Then try:Remove any items you can reach.?For those items you cant remove from above, run the snake down the ventilation pipe. A Dagenham Plumber is trained to do this.Push the end of a garden hose into the ventilation pipe and get a friend or family member turn on the water for you.? You should then hear sudden whooshing sound when the water forces the clog down the drain.