HG Liquid Drain Unblocker is very safe. As the product is ready for use, there is a much smaller chance of splashes. There is no danger of making the blockages worse, as can be the case with powder or granular products. HG Liquid Drain Unblocker is thorough and effective and save to use on plastic pipes. Carefully pour 300ml of HG Liquid Drain Unblocker in the blocked trap. Wait about 30 minutes for the substance to work and rinse thoroughly with cold water. With stubborn blockages rinse through first and then again afterwards with hot water. If this fails to clear the blockages, repeat the operation or leave the product to work overnight. Unpleasant odours from sink holes can be effectively got rid of with a few drops of HG Liquid Drain Unblocker.