A common household plumbing problem is the leaky faucet. A drip is caused by seepage from the water supply. Water enters your home under pressure and must have a watertight seal holding back the incoming water. The seal is created by a washer tightly pressed against the faucet seat.  When the washer wears out, water can leak through and drip out of the faucet spout. We all know that will cost money especially if it is a hot water drip because that water is heated before it drips down the drain.  Also, before you attempt to work on your faucet remember to turn off the water supply.