Plumbing drains are a maze of twists and turns and can become clogged from time to time. There are a few things you should never allow to go down the drain. Tea leaves and rice will swell and clog the line, while grease will harden and cling to the insides of your drains causing flow problems. If the drain is running slow, try pouring several kettlefulls of boiling water down it. This remedy works especially well on kitchen sinks where grease buildup is the usual cause of drain problems. When the drain is completely blocked, use a plunger or 'plumbers friend' to loosen the buildup. The ideal method of unclogging a drain with a plunger is to partially fill the sink so that the drain opening is covered with water and place the rubber cup of the plunger over the drain opening, completely covering it. Work the plunger handle up and down to dislodge the buildup. Bathroom sinks are different. Typically, they are equipped with pop-up drain stoppers, which can entangle hair and cause flow problems. Be sure to remove them once a week, and clean out the hair and bits of soap. If all efforts have failed to clear the drain, it's time to call a professional plumber.