Citric acid can remove limescale and other deposits from both the inside and outside of household pipes. While there are many commercial cleaners that contain citric acid, you can use lemon juice for a natural concentration of citric acid to clean your pipes. Use citric acid to help clear slow drains and flush your drains regularly with a citric acid solution as part of your regular bathroom and kitchen cleaning and maintenance.
Heat 1/4 cup salt and 2 quarts water together until almost -- but not -- boiling. Pour the salt water down the drain. Allow the water to drain into the pipe, if the drain is slow.
Add 1/2 cup baking soda to the drain.
Pour 1/2 cup lemon juice into the drain. Allow the baking soda and lemon juice to work for about 30 minutes.
Cut a lemon in half and rub it on the surface of the exposed pipes while the baking soda and lemon juice work on the inside of the drain. Wipe the lemon juice off with a damp sponge.
Heat 1/2 cup salt in 4 quarts water to hot but not boiling. Pour the salt water down the drain.
Repeat the steps if the drain remains slow.
Commercial citric acid or "sour salt" can be dissolved in warm water and used instead of the lemon juice.
Do not add lemon juice to a drain that has recently been treated with commercial drain cleaner, as it can produce toxic gases.