Is Caustic Soda Safe for Cleaning Drains at Home?

Caustic soda, also called lye or sodium hydroxide, is sold for unblocking drains and for heavy cleaning. It works, but it is also one of the most dangerous chemicals you can keep at home. Here is when it is useful, when to avoid it, and how to stay safe.

What it is good for at home

• Grease-blocked kitchen drains: caustic turns fat into soap that can be flushed away.
• Oven and grill cleaning: many heavy-duty oven cleaners are based on caustic.
• Soap making: handmade soap is made by reacting oils with lye, using careful recipes.

When not to use it

• On aluminium pans, utensils or fittings. Caustic attacks aluminium and gives off flammable hydrogen gas.
• On painted surfaces, wood or some plastics, which it can damage.
• After an acid drain cleaner, or together with any other drain product. Mixing can cause violent reactions and splashing.
• In a drain that is completely blocked with standing water, where the solution can splash back when the blockage clears.
• If you have children or pets and cannot store it securely.

Safe use, step by step

1. Wear eye protection and rubber gloves. Ordinary glasses are not enough.
2. Open a window for ventilation.
3. If you need a solution, add the caustic slowly to cold water in a plastic bucket. Never pour water onto caustic; it gets very hot and can spit.
4. Pour slowly, keeping your face away from the drain.
5. Flush with plenty of water afterwards.

Storage

Keep caustic soda in its original, labelled, tightly closed container, high up and locked away from children and pets, away from food and away from acids. Never put it into a drinks bottle.

First aid

• Eyes: rinse with running water for at least 15 minutes and go to a doctor straight away.
• Skin: remove contaminated clothes and rinse with water for at least 15 minutes.
• Swallowed: do not make the person vomit. Rinse the mouth and get emergency help immediately.

Buying it for work

For businesses in Oman buying caustic soda in bulk, with the safety data sheet and certificate of analysis supplied, see Muscat Chemical's caustic soda page.