Gate valves are used to control the flow of water in your piping and are commonly found on the outside of the home. Unlike ball valves, they require multiple turns to open or close. You can use them to set the water flow through the piping because of this fine-adjustment feature. If you notice your gate valve is beginning to leak, don't rush out to the hardware store to buy a replacement. A lot of the times worn out packing inside the valve causes the dripping. The solution: replace the worn out packing.
Shut the water supply off to the valve. Look for a valve upstream from the one you are repairing. If you don't find any, shut off the main water supply valve.
Open the faucet all the way. Place one wrench just beneath the packing nut of the gate valve. Place another on the valve itself. Turn the first wrench to remove the valve assembly.
Remove the faucet handle with your socket wrench by loosening the retainer nut. Place an adjustable wrench on the packing nut and loosen it. Slide the nut up the stem and off of the valve assembly.
Locate the packing washer inside the packing nut. Pry it out with a screwdriver.
Place a new packing washer inside the packing nut. Confirm that it is an exact match of the one you removed. Slide the packing nut back over the valve stem and screw it onto the valve assembly.
Place the valve handle back on the valve assembly and screw on the retaining nut. Tighten down with your socket wrench.
Ensure that the valve is fully open then screw the valve assembly back onto the valve. Place one wrench on the assembly and one on the valve. Tighten the valve assembly to the valve.
Tighten the packing nut until snug. Close the valve and turn on the water supply. Examine to confirm that this fixed the leak.