This reaction works only on blockages. Caustic soda will not dissolve mineral deposits (limescale, rust) or inorganic debris (sand, gravel, plastic).
For outside drains, a mechanical auger (manual or electric) is safer and more reliable for clearing blockages. For grease, hot water + dish soap followed by an enzymatic cleaner over 24 hours is surprisingly effective without the risks. caustic soda for outside drains
Caustic soda is a highly effective but hazardous chemical cleaner used to clear organic blockages in drains. For (e.g., kitchen waste pipes, surface water drains, sewage outflow pipes), it can offer a rapid, powerful solution for grease, fat, hair, and soap scum. However, its use carries significant risks: it generates extreme heat (exothermic reaction), can damage certain pipe materials, poses severe safety hazards to humans and animals, and may harm the external environment (soil, groundwater). For outside drains specifically, alternatives like enzyme cleaners or mechanical augers are often safer and more environmentally responsible. This reaction works only on blockages
: Mix 1 liter of cold water with roughly 60g (about 3–4 tablespoons) of caustic soda flakes in a plastic bucket. Always add the soda to the water , never the other way around, to prevent a dangerous "spit back" reaction. For grease, hot water + dish soap followed