A frost-proof yard hydrant is commonly installed when you need to access water at a location too far away for a garden hose to conveniently reach a standard exterior faucet. Typically a yard hydrant installation is comprised of a buried horizontal pipe that leads to a long, vertical pipe, called a standpipe, that automatically drains the water out each time the hydrant is shut off. The bottom of the standpipe reaches below the frost line—the depth to which the ground freezes in winter. The water drains out of the faucet and standpipe and into the unfrozen ground, thereby leaving no water that can freeze in the upper portion of the hydrant.
A yard hydrant must work properly to prevent freezing. If you have tried to repair a dripping hydrant without success, or if you find that a piece has broken, you may need to replace the hydrant altogether. Replacing a yard hydrant is not difficult but it can require a fair amount of digging to reach the fitting and supply pipe buried below the frost line.
In our example, the old yard hydrant is connected to an iron water-supply pipe running underground. Your project may differ somewhat if your water supply pipe is made of copper or PVC.
Equipment / Tools
- Pipe wrenches (2)
- Garden hose
- Penetrating oil (as needed)
- Plumber's thread-seal tape or pipe-joint compound
- 1/2-inch gravel for drainage
Dig Out the Old Hydrant
Shut off the water supply to the hydrant, and open the hydrant's faucet to remove any pressure in the line.
Dig a hole around the hydrant to expose the standpipe, using a standard shovel (no power equipment) to prevent damaging the pipe. Remove enough soil and gravel around the fitting at the bottom of the standpipe to have sufficient room to work.
Don't be surprised if you don't reach the standpipe fitting quickly. In cold-weather climates, the frost line can be 3 to 4 feet deep, or even more. Be prepared for a lot of digging. Having helper and taking turns digging is often a good idea.
Remove the Old Hydrant
Unscrew the standpipe from the fitting, using two pipe wrenches: Use one wrench to hold the fitting in place so it does not twist or move, and use the other wrench to twist the standpipe in a counterclockwise direction. If the standpipe is difficult to turn, soak the pipe threads (where the pipe meets the fitting) with penetrating oil, such as Liquid Wrench or WD-40. Let the oil sit for 15 to 30 minutes, then try again to remove the pipe. Repeat the oil application, if necessary.
Be careful not to let dirt or gravel fall into the pipe fitting when the standpipe is removed. If some dirt or debris falls in, vacuum it out with a wet-dry shop vac. Or, you can turn on the water supply for a few seconds to flush debris out of the pipe fitting.
Install the New Hydrant
Apply plumber's tape or pipe-joint compound to the threads on the standpipe of the new yard hydrant. Thread the standpipe into the underground fitting, again using two pipe wrenches—one to hold the fitting and the other to turn the pipe. Tighten the standpipe snugly, stopping when the faucet faces in the desired position. Be careful not to over-tighten the standpipe.
Make sure to buy a yard hydrant with a standpipe that is equal in length to the old hydrant. Hydrants come with standpipes designed for "bury depths" of 1 foot to 5 feet or more. The proper bury depth is based on the depth of the winter frost line in your region.
Test the New Hydrant
Turn on the water supply to the hydrant and check all of the connections for leaks. Test the hydrant by attaching a hose to it and positioning the end of the hose well away from your hole, then open and close the hydrant faucet. Look into the bottom of the hole as you turn off the water at the hydrant: The water from the standpipe should drain out through the drain valve at the base of the standpipe.
Backfill the Hole
Begin filling the hole with 1/2-inch diameter drainage gravel up to about 3 inches above the hydrant's drain valve; this ensures that water draining from the standpipe will flow away from the valve. Fill in the remainder of the hole with soil, compacting it with your feet as you go.