How to Repair a Frost-Free Yard Hydrant

A frost-free yard hydrant is just a variation on a standard compression faucet, in which a plunger at the end of a plunger stem opens and closes against a water inlet to control the flow of water. In the case of a yard hydrant, the plunger is fitted onto the end of a long pump rod that runs down inside the vertical standpipe to the valve body. This pump rod is long since it needs to reach where the water pipe is buried. 

Yard hydrant troubleshooting typically involves extracting the pump rod and replacing the plunger, which restores the hydrant's ability to seal off the water flow. Learn to repair a frost-free hydrant if it's leaking from the top, the lock nuts that hold it in place, or even underground.

How a Frost-Free Hydrant Works

A frost-free hydrant can be thought of as a very long compression faucet. The horizontal water pipe running out to the hydrant location from the house must be buried deep enough to be below the frost line, which in some climates can be 4 feet or more below ground. The actual valve body is located at the junction where the horizontal pipe turns upward into a vertical standpipe. The standpipe is typically a 1-inch diameter galvanized pipe threaded at the top.

At the top of the standpipe, usually 3 to 4 feet above the ground, the hydrant head is screwed onto the pipe. The hydrant is a specialized type of faucet that uses a fulcrum-type lever to raise and lower a long pump rod (sometimes called an operating rod or riser rod) inside the standpipe. At the bottom end of the pump rod is a plunger with a rubber washer or seal fitted to the end. The valve is designed so that when the hydrant's handle is lowered, the pump rod and plunger squeeze the water inlet to stop the water flow. Raising the hydrant handle lifts the plunger from the water inlet, allowing water to flow up the standpipe and out the spigot.

Common Problems With Yard Hydrants

What makes a hydrant frost-proof is its design variation that features a drain port built into the bottom of the valve. When the pump rod and plunger lift away from the valve seat, this drain port is blocked, forcing water to flow up the standpipe. However, when the pump rod and plunger are lowered to close against the water inlet, the drain port is opened and any water in the standpipe drains into the ground—the surrounding area is usually packed with gravel to facilitate drainage.

Since no water remains in the pipe, it cannot freeze and cause the pipe to rupture. But if a leaky hydrant is not fixed, it can be susceptible to bursting, since water remains inside the standpipe. Yard hydrant plunger replacement is a simple and quick repair to ensure your hydrant remains leak-free and prevents bursting.

There are many types of hydrants, and getting the exact replacement parts for your model is important. Many hydrant manufacturers offer yard hydrant repair kits for their products, and many repair kits are universal to fit a variety of brands. Check with the manufacturer or shop for parts online or through a local plumbing supply house.