Most kitchen drains can be unclogged by pouring in 1 cup of baking soda followed by 1 cup of hot vinegar (heat it in the microwave for 1 minute). Give it several minutes to work, then add 1 litre of boiling water. Repeat if necessary. If you know your drain is clogged with grease, use 1⁄2 cup each of baking soda and salt followed by 1 cup of boiling water. Let the mixture work overnight, then repeat if necessary.