Look for branded drain unblockers (e.g., Mr. Muscle) in the household cleaning aisle. Always wear gloves and goggles, ventilate the area, and keep away from children/pets.
If you need content for informational or safety purposes, here is appropriate messaging: Caustic soda is dangerous if mishandled. It can cause severe burns to skin and eyes, and damage surfaces. Sainsbury’s advises customers to follow product labels strictly. For drain cleaning, consider enzyme-based or less hazardous alternatives available in-store. caustic soda sainsburys
Pure caustic soda is more likely found at hardware stores (e.g., B&Q, Screwfix, Toolstation) or online chemical suppliers. If you meant something else (e.g., a product lookup, an SDS request, or content for a different audience), please provide more context so I can tailor the answer appropriately. Look for branded drain unblockers (e
