Do you have a clogged sink, tub or shower drain? Often grease, hair and rust can slow or clog up drains. Draino or similar products can be expensive and you may not always have them around.
Try spraying WD-40 in the drain (without any water in it). Let it sit for 10 minutes. The magic of good old WD-40 will do it's work getting under buildup and rust and breaking it down. Rinse it down with water and if that is not enough use a plunger. Your clog should free and your drain should flow like new.