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  • How to Replace a Frost-Free Hydrant

    December 22, 2023 11 min read 0 Comments

    Frost free hydrant installed next to a hoop house with yellow and red flowers visible in the foreground.

    How to Replace a Frost-Free Hydrant

    Replacing a frost-free hydrant may seem like a challenging task, but with the right tools and a bit of guidance, you can tackle this project successfully. This article will walk you through the process of replacing your frost-free hydrant step by step, providing helpful tips along the way to ensure that your new hydrant functions optimally and stands up to the test of time. So, roll up your sleeves, and let's get started on making your outdoor water access more convenient and reliable!

    Understanding Frost-Free Hydrants

    A frost-free hydrant, also known as a frost-free yard hydrant or frost-proof hydrant, is an essential outdoor water source that prevents freezing during cold weather. These hydrants have a unique design that allows water to drain out each time they're shut off, ensuring a safe and functional water supply even in freezing temperatures. In this section, we'll discuss how frost-free hydrants work and their main components.

    Frost-free hydrants are designed with a buried horizontal pipe connected to a long, vertical standpipe 12 inches below the frost line. The length of the standpipe ensures that it's below the frost line, preventing water from freezing within it. The hydrant's main valve is located at the bottom of the standpipe, connected to the water supply line.

    When you turn on a frost-free hydrant, the plunger is lifted off of the main supply of water. There is space around the plunger in the valve to allow water to flow around the plunger and up the spigot. That is why it takes a second for the water to come out when you open up that hydrant in northern Minnesota! 

    As you turn off the hydrant, the hydrant's plunger is lowered, plugging the supply of water and exposing the standpipe drain, enabling any leftover water inside the standpipe to automatically drain back down into the ground well below the frost line. This drainage action prevents water from freezing within the hydrant and minimizes the risk of damage or rupture from frozen water inside the pipe. Lack of drainage will cause water to stay in the pipe, freeze, and destroy all of your hard work. Always be sure to pour a few gallons of water in the hole when working on a frost-free valve. It's easy to add gravel when the hole is dug to improve drainage. It is a nightmare to wake up to a frozen hydrant; you always discover it when you NEED WATER! 

    Proper installation and maintenance are crucial to ensure the longevity and functionality of your frost-free hydrant.

    Now that you understand how frost-free hydrants work, you'll be better prepared to replace or repair one as needed. In case of any leaks or malfunctions, you can fix the problem efficiently and ensure your hydrant remains a reliable outdoor water source throughout the year.

    Frost Free Hydrant Installed near a Gothic Hoop House in the Winter

    Why Replace a Frost-Free Hydrant

    One of the main reasons for replacing a frost-free hydrant is due to leaks. Leaking hydrants not only waste water, but they can create a significant mess in your yard or garden. Over time, the constant moisture created by a leak could lead to damage to nearby structures and plants. Addressing and fixing leaks as soon as you notice them should always be a priority.

    Damage to the hydrant's exterior is also a reason for replacement. Frost-free hydrants are designed to withstand harsh weather conditions but are not indestructible. 

    When you notice these issues, it is important to evaluate the situation and determine if a frost-free hydrant replacement is necessary. Doing so will help save water, maintain water pressure, and reduce the likelihood of pipes breaking due to freezing.

    Before jumping to replace your frost-free hydrant, it's essential to understand the different components that make up this helpful outdoor water source. Likely, your hydrant may simply need some adjustment or a new plunger, which avoids any excavation!

    Identifying the Parts of a Frost-Free Hydrant

    A frost-free hydrant consists of the handle on the above-ground portion of the hydrant, known as the head casting. When you operate the handle, it uses a fulcrum-type lever to move the operating rod within the standpipe.

    The other component is a valve body buried below ground. It must be buried below the frost line to prevent freezing. This valve connects to the main water supply line, and the standpipe comes up from the valve below the frost line up to the faucet above ground. The valve body includes a drain hole that allows water to empty out of the standpipe when the hydrant is turned off. This subterranean drain must be buried in well-draining sand or gravel to reliably drain water quickly. This quick draining is essential to prevent any water from freezing in or around the standpipe. 

    The plunger seals against the valve seat or is lifted off the valve seat to start or stop the water flow. When the plunger is open (allowing water to flow), the drain in the valve is covered by the plunger. When the plunger is closed (blocking the flow of water out of the valve body), the plunger is actually below the drain in the valve body.

    This allows the water in the standpipe to drain back below the frost line, so there is no water to freeze and burst your pipe. The plunger can be of several designs, but they all will use rubber of some kind to press against the metal seat. Being below ground and away from light,, the plungers tend to last for quite a long time, but as with anything rubber,, they eventually dry out and crack. These leaks will come up and out of the faucet while the operating rod is in the closed position.

    The operating rod has a packing nut, typically made of brass, that helps maintain a watertight seal. The packing nut is tightened against a graphite packing, which forms a seal against the operating rod. Over time, graphite does wear off of the inner diameter of the packing.

    The packing nut can be used to squish the graphite, thus forcing it to contact the operating rod and potentially stopping a small leak. The brass nut is soft, but the graphite packing is downright buttery. Care must be taken to only tighten the packing nut as much as is absolutely necessary. If you are only getting a leak at the operating rod when the water is flowing, there is a good chance this is your fix!

    Tip:  A replacement graphite packing may also be worth a try (they are included in a hydrant rebuild kit)

    There is also a set screw allowing you to adjust the operating rod, thereby allowing you to adjust the pressure applied to the plunger. Adjusting the operating rod can, in some cases, solve a leak and is worth a look before any excavation commences!  

    When Should You Replace a Frost-Free Hydrant?

    Replace a frost-free hydrant ONLY when you are sure there is a problem. I have seen instances where people have gone as far as to pay an excavation company to dig a hydrant, and it was a situation where a new plunger would have solved the leak. This would have saved hours of labor, machinery use, transportation of equipment, and raw material to make the new frost-free hydrant. 

    Tools Required for Replacement

    When it comes to replacing a frost-free hydrant, some form of excavator or earth-moving equipment is the preferred way to go, but you can absolutely replace your hydrant with a shovel. A pick helps. A spud bar/rock bar/ tamper with a sharp end can also help break up compacted soil and, remove rocks, and get you through frost. My preferred method to date in winter, if an excavator is not an option, is an electric jackhammer with a flat-edged spade attachment. 

    Once you get to the point of doing any actual plumbing, you'll need a pair of pipe wrenches. Pipe wrenches are to be used as a pair in order to get a good solid grip on the pipe, and the fitting the main line uses to attach to the valve and the pipe at one time. This allows you to prevent any kinking or movement in the other fittings (these are just great to have around; I use mine all the time!)

    Penetrating oil can be a lifesaver when dealing with stubborn or rusted connections. A bit of this lubricant sprayed onto the threads can help loosen the bond, making it easier to remove the old hydrant or make adjustments during installation.

    Thread sealant rated for potable water. Keeping some of this on hand is essential. When used properly, thread sealant really shouldn't be getting into the water, but with there being the possibility of the sealant making it into our food supply, it is best to get thread sealant rated for potable water.

    Understanding the Cost of Replacing a Frost-Free Hydrant

    When replacing a frost-free hydrant, it's essential to understand the costs involved. You'll want to account for the new hydrant's price and any additional replacement parts needed, such as pipes or fittings. Remember, if you are going to have a company do the excavation, that cost will be far greater than the cost of any make of hydrant. 

    Generally, a frost-free hydrant can cost between $100 and $250. The exact amount will depend on the specific model and brand you choose and any features you may want, such as an anti-siphon device or a backflow preventer. If you’re using your hydrant for things like washing veggies for commercial use, you may need to consider a food-safe frost-free hydrant. This type of hydrant drains the water below the frost line to prevent any possible contamination.

    Regarding replacement parts, these costs can vary, but you should expect to spend around $20-50 on average. These kits are typically quite complete and will cover any maintenance that may be required. 

    Steps to Replace a Frost-Free Hydrant

    Replacing a frost-free hydrant is a manageable task that you can do with some preparation and the right tools. Follow these steps to ensure a proper replacement and installation.

    1. Shut-off water supply - Before you begin, shut off the water supply to the hydrant. 
    2. Excavate around the old hydrant - Be sure to excavate a large enough hole to work in safely. Depending on the depth of the frostline in your area, you may need to build shoring or step the walls of the hole to ensure the risk of collapse is averted. 
    3. Prepare the trench: If installing a new hydrant in a different location, dig a trench from the water pipe to the chosen spot. The trench should be deep enough so that the hydrant sits below the frost line to prevent freezing. Again, we are going to be conscious about the depth of the trench relative to its width in order to prevent a collapse.
    4. Remove the old hydrant - The old hydrant will likely be rusted to the fitting on the main water line. We are more than likely replacing it because corrosion has caused the hydrant to leak or the ground around the hydrant is no longer draining. This means we are to expect a mess and corroded fittings. A penetrating oil and the pipe wrenches in tandem will help to accomplish the removal.
    5. Connect the new hydrant - Apply potable water-rated thread sealant to the threads of the water pipe and attach the new frost-free hydrant. Make sure it's securely tightened to prevent leaks.
    6. Set Hydrant - I like to find the grade on each side of the hole and put a 2x4 across to see precisely where my hydrant faucet opening will be when the hole is backfilled. Make sure it's the height you want ( you can get a deeper bury depth hydrant if you're going to bring the faucet higher, but do not ever raise the base of the hydrant above the frost line).
    7. Test the hydrant - YES, do this BEFORE burial of the hydrant and line. You can see the water draining when you turn off the hydrant. You can see the fittings and the soil draining the water when the hydrant is turned off. This is our final chance to catch anything we are not happy with and make a change before it becomes a significant event!  Turn the water supply back on and test the new hydrant for leaks. You may need to make adjustments to the handle. If the water doesn't drain, dig a hole around the base of the hydrant and add gravel; don't skimp!
    8. Bury the hydrant - Now, carefully bury the hydrant, starting with sand or gravel and working back to the top soil last. Backfill a few inches at a time, and make sure to check and double-check that your standpipe is plumb. Compact the soil as you go, taking care of the pipe and fittings during your first couple of compactions. 
    9. Final adjustments - If necessary, you can adjust your operating rod or the packing nut, but for the most part, your hydrant is ready for years of service with little to no maintenance!


    Replacing a frost-free hydrant may seem daunting, but with the right approach and tools, you can make sure your hydrant is functioning optimally year-round on your homestead.

    We've covered the main aspects of this process, from understanding how frost-free hydrants work to replacing one step by step. It's important to remember that frost-free hydrants offer an essential outdoor water source that provides a safe and reliable water supply even in freezing weather.

    With these tips in mind, you can tackle your situation confidently and trust that your homestead's water supply will remain functional. Now go out there and cross this project off your list!


    Frequently Asked Questions

    How can I troubleshoot a stuck plunger?

    If your plunger is stuck, try loosening it by gently tapping on the top of the hydrant with a rubber mallet or a piece of wood. If this doesn't work, and you suspect the plunger is frozen, you can  shut off the water supply and remove the head casting with your pipe wrenches. (Careful to hold the standpipe still against the turning action of the pipe wrench on the head casting.) 

    Now, you can pour some scalding water down the standpipe in order to help thaw the frozen water holding the plunger down. You may need to add more hot water to thaw it enough to set it free. Inspect the plunger. If it is damaged, replace it. If the standpipe does not allow water to drain, you may need to dig up the hydrant and check if it needs replacing or the hydrant “ drain field” needs attention.

    What is the proper depth to bury a hydrant?

    The proper depth to bury a hydrant depends on your local frost line depth. This is the maximum depth at which the soil will freeze during the cold months. To ensure your hydrant operates correctly, bury it at least 12 inches below the frost line.

    How Can You Check the Drain of Your Frost Free Hydrant?

    You can check your frost-free hydrants drain by turning on the water, shutting it off, and quickly putting the palm of your hand on the faucet opening to form a seal. If your drain is working, the faucet should suck to your hand from the vacuum of the water draining down and out of the standpipe. 

    You can also put a glass or jar up to the faucet, turn it on until it is full, and when you turn the faucet off, submerge the faucet opening in your full glass of water. The water draining down the standpipe will siphon the water out of the glass until the seal is broken by air. It is kind of a fun little test to see the health of the little “drain field” below the frost line.

    It can be extremely disheartening when we don't get those fun results, but we need to know when a hydrant is acting up as soon as there are symptoms. You will always discover a frozen hydrant when you need water and it is cold enough to freeze your hydrant.

    How can I repair a cracked head on a hydrant?

    This is a replacement situation. The heads are cast iron and relatively affordable for the amount of convenience they provide. Each manufacturer will have instructions and diagrams available for their hydrants. I recently got parts and a diagram for a hydrant installed in 1954!