You typically find a vacuum cap to a freezeproof faucet, which is an exterior faucet with a valve chamber long enough to store water within the house to keep it from freezing. The cap covers just a one time valve which allows air to the chamber once the faucet is off to ensure water will escape. The valve, referred to as a vacuum breaker, is typically made of plastic, and when it overlooks, water can spray from it when the faucet is on. If the faucet leaks when it is off, however, the problem is generally a worn valve stem washer.
Switch off the faucet and pry the vacuum breaker cap with a pair of flathead screwdrivers.
Unscrew the breaker maintaining nut. It’s typically made of plastic, and you should have the ability to flip it with your fingers. In case you can’t, utilize adjustable pliers.
Pull the vacuum breaker with your hands and clean debris from it using a rag. If there are mineral deposits on it, scrape them off with one of the screwdrivers. Replace the breaker, screw to the retainer, replace the cap and then turn on the faucet. If water still leaks from the cap, then choose the retaining nut and then breaker into a hardware store and purchase replacements.
Replace the valve stem washer if the faucet leaks when it is off. To try it, you are going to have to switch off the water into the faucet.
Unscrew and remove the faucet handle with a Phillips screwdriver, then unscrew the retaining nut, which holds the valve stem in position, with adjustable pliers. After the nut is off, screw the handle back on and use it to pull on the stem from the valve chamber.
Unscrew the screw which holds the washer to the end of the valve stem using a Phillips screwdriver. Pull the washer and replace it with a brand new one.
Push the stem back into the valve chamber, remove the handle again and screw to the retaining nut. Replace the handle and turn onto the water to your faucet.