Frost-proof yard hydrants are standard water fixtures for outdoor use in northern climates where freezing temperatures are common. Frost-proof hydrants operate with a control lever and hose connector faucet above ground, while the operating valve is below ground at a depth where freezing conditions do not occur. Each time the hydrant is shut off, the water in the upright portion of the pipe drains out of holes in the base of the pipe, leaving no water in any portion of the hydrant subject to freezing conditions. Most do-it-yourselfers can install a frost-proof hydrant, although the project involves excavation to a level below the frost line.
Excavate a hole for the frost-proof hydrant at least 2 feet in diameter and to a depth below the frost line for your area. The frost line is defined as the depth the ground reaches freezing temperatures during the winter in that area, and varies from area to area.
Attach an elbow to the base of the hydrant if the hydrant is the end of the water line. Attach a T-fitting to the bottom of the hydrant if the water line continues to other fixtures.
Connect the water line to the fitting at the base, using appropriate methods based on the materials of the existing water line. PVC or other synthetic material water pipes are glued to the fittings using the appropriate glue. Adding a frost-proof hydrant to a metal water line may involve cutting threads into the water pipe, or soldering the fitting to the pipe, depending on the situation.
Fill the base of the excavation hole with 1/2-inch gravel (gravel screened to a minimum size of 1/2 inch), to a level at least 3 inches above the drain opening in the brass housing at the base of the frost-proof hydrant.
Test the function of the hydrant by introducing water to the line. When the hydrant is open, water should exit from the faucet opening. When the hydrant is closed, the water in the hydrant's vertical pipe should drain into the gravel area at the base of the hydrant.
Fill the rest of the excavated hole with the soil removed during the earlier excavation. Keep the hydrant vertically straight while adding and tamping the soil in place.