Non-chemical drain cleaners

If your drain is clogged, this may solve the problem without resorting to corrosive chemicals.
WARNING: Do not use this method for plastic pipes or if you have already tried a regular drain cleaning product, due the danger of chemical reactions.

Option one
½ cup baking soda
½ cup white vinegar
Tip the baking soda into the drain, followed by the white vinegar. Leave for 15 minutes. Pour a kettle full of boiling water down the drain to clear. The reaction between the baking soda and vinegar helps break down fatty residue in the drain, while the boiling water washes it all away.

For a milder cleaning solution:

Option two
½ cup salt
4 litres hot water
Juice of one lemon
Mix, pour down drain

Option three
¼ cup salt
¼ cup borax
½ cup vinegar
Pour into the drain in the order listed, dry ingredients first. Leave for 15 minutes. Flush the drain with plenty of hot water.