If you decide to proceed despite the risks, follow these safety rules exactly.

Caustic soda generates intense heat (an exothermic reaction ) when it meets water. This heat can soften or warp modern PVC plastic pipes or erode older metal pipes, leading to leaks over time.

Mixing caustic soda with other household cleaners, especially bleach, can release dangerous chloramine gas , which is toxic if inhaled. How to Use Caustic Soda Safely (If You Must)

Caustic soda is a fantastic chemical for dissolving organic clogs in metal sink drains. But in a porcelain toilet, the risks of cracking the bowl, injuring yourself, or ruining your septic system far outweigh any benefit. Put the caustic soda away and reach for a plunger or an auger instead.

While caustic soda is effective in metal pipes or sink drains, toilets present a unique set of dangers.