For generations, the humble orange-and-red box of bicarbonate of soda (also known as baking soda) has sat quietly in kitchen cupboards, ready for cakes, cookies, and deodorizing the fridge. But beyond its culinary uses, this fine white powder is one of the most effective, cheapest, and environmentally friendly weapons against one of the home’s most annoying problems: slow, smelly, or clogged drains.