They're available at most grocery, hardware, and "big box" stores. Use this method only as a last resort. The chemicals used in drain cleaners are toxic to people and pets, corrosive to pipes. Also, chlorinated drain cleaner are very damaging to the environment.  If you suspect that there is a hard obstruction, do not use a chemical solution. Instead, use a snake or call a plumber. Only use chemicals that are specifically made for toilets. Using other drain cleaners may damage your toilet. Be sure you follow the manufacturer's instructions. Keep the lid down to prevent toxic fumes from filling your bathroom.  Never use a plunger right after adding the drain-cleaning chemicals. The chemicals could possibly shoot back up onto your skin. Make sure the bathroom is well ventilated so you won't inhale the chemicals.
قم بشراء مواد كيميائية لتنظيف المصرف. قم بصب الكمية المحددة في المرحاض.