Fix an outdoor faucet that leaks around the handle by tightening the packing nut located behind the handle. For faucets that leak through the spout, or if tightening the nut does not stop a handle leak, remove the valve stem assembly and replace the packing washer and the washer at the base of the stem.
Frost-free outdoor faucets are more difficult to fix than simple boiler drain faucets. Remove the valve-stem assembly by shutting off the water supply at the main valve into the home. The valve could be located in the basement, attached garage or crawl space. Relieve the water pressure and ensure the water is off by opening the outdoor faucet. Loosen the screw that holds the handle in place, and pull the handle straight out to remove it. Use a wrench to loosen the packing nut while holding the faucet with the other hand to keep it from turning.
Pull the valve-stem assembly from the faucet, and check both washers. Loosen the retaining screw at the bottom of the assembly to remove the valve washer. Slide the packing washer off the valve stem or from inside the packing nut. Take both washers to a plumbing supply or home improvement store, and purchase exact replacements. Install the new washers, and tighten all fittings until they are snug. Avoid overtightening the fittings.