How To Insulate Buried Water Lines—6 Methods To Consider

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With temperatures dropping and winter well on its way, you are likely worried about your water lines freezing. Exposed pipes can be rather simple to insulate, but how do you insulate buried water lines? Our crew set out to find the most effective methods to keep your pipes from bursting this winter. See our findings below.

If your pipes have not yet been installed, now is the best time to insulate them. If the pipes are already buried, you may need to dig them up. The following methods are the best ways to insulate buried water lines: 

  • Bury below frost level
  • Pipe heating cable
  • Foam pipe insulation
  • PVC coverings
  • Use proper backfill
  • Cover ground in hay or leaves

Underground Sprinkler System to Water the Yard Man Working with Pipes in Ground. How To Insulate Buried Water Lines—6 Methods To Consider

How to Insulate Buried Water Lines

With most things unseen, they are out of sight, out of mind. However, during frigid temperatures, this mindset can get you into big trouble with your water lines. If you don’t take the extra steps to make sure they are properly insulated, your pipes could not only freeze, but they could also burst, leaving you with no running water along with a huge mess to clean up once the pipes thaw.

open trenched with a black sprinkler water line being repaired

Bury Below Frost Level

As with most things, prevention is key when it comes to keeping your pipes from freezing or bursting. The first step should be to find out what the frost level is in your particular location. This level indicates how far you must dig before the ground stops freezing. However, some regions have high water tables, making it impossible to bury the lines deep enough.

To find your area’s frost line, you can rely on a postal code search through the National Weather Service.

Pipe Heating Cable

When you are cold, you probably enjoy standing next to the heater or snuggling under an electric blanket. You can do the same thing for your water pipes with pipe heating cable. These electric cables are easy to install, and they are self-regulating with the outside temperature.

Simply tape the cables to your plastic or metal water lines and plug them into an outlet. Not only is this cable pre-assembled and easy to use, but it also only works in temperatures less than 37 degrees Fahrenheit, saving you money and preventing pipes from overheating.

You can find pipe heating cables on Amazon.

Check out this YouTube video on installing pipe heating cable:

Aluminum Tape

Although you should not use aluminum tape as an insulator for your water pipes, you can place it over the heating cables. Covering the cables with aluminum tape will allow the heat to be dispersed evenly around the pipe rather than in one spot.

Industrial Air-conditioning Ductwork and Pipework In Commercial Building Fitout

Amazon has aluminum tape.

Foam Pipe Insulation

Whether or not you choose to use heating cables, foam pipe insulation is one of the best ways to insulate buried water lines. Not only will it keep your pipes warm during the winter, but it will also prevent them from sweating during the summer. It is relatively cheap and straightforward to install. Most come pre-slit, so there is no need to feed the pipe through. Some even feature self-closing ends.

Click here to check out foam pipe insulation on Amazon.

PVC Coverings

PVC coverings will help protect your water lines and prevent freezing. You can use it with or without foam insulation. PVC pipe will help keep your lines warm without foam or heating cables, but when you combine the three, you have an almost foolproof insulation system.

When using it over foam, make sure you purchase a PVC pipe that is large enough to fit your water lines comfortably.

mechanical excavator bucket shoveling sand

Use Proper Backfill

Once you have properly insulated your pipes, it’s important to use the right material to fill the hole. Some backfill, such as dirt or clay, does not add any insulating properties to your hidden pipes. Sand, on the other hand, will stay in place better than dirt, and it also possesses insulating qualities.

Make sure to pack it down really well. This will aid in keeping your pipes warm and prevent you from having a sinkhole in your yard.

Click here to view this sand on Amazon.

Cover Ground in Hay or Leaves

When you know a freeze is heading your way, go ahead and pile some leaves or hay on top of the dirt where buried water lines exist. This will help keep the ground a bit warmer, trapping heat inside. If you live in an area with lots of snow, you can use it as an insulator. It sounds a bit counteractive, but as long as the snow doesn’t melt before the next big freeze, it will help hold heat in the ground.

Leave Faucets Dripping

Although leaving your faucets dripping won’t insulate your pipes, running water is much less likely to freeze. When you expect the temperatures to reach below 20 degrees Fahrenheit, leave several of your faucets dripping water. If you are worried about waste, place a pot under the faucet to catch excess water. You can then use it for washing dishes, making coffee, or other household needs.

Additionally, if you are concerned about this method increasing your water bill, it will be much cheaper to pay a little extra on your water bill than it will be to hire a plumber to fix busted water lines.

Emptying Your Water Lines

If you will be gone for some time, you don’t want to have to worry about coming home to busted pipes. In these cases, since you won’t be using the water for an extended period of time, you can empty the water from all your pipes, protecting both indoor and buried water lines.

Shutoff Valve

The first thing you should do is find the water shutoff valve. This will turn off the water to all the pipes. Next, it’s time to drain all remaining water from the lines. For this step, you’ll need to locate a faucet at a low point. This will allow gravity to do its work, pulling all the water out.

Attach a hose to this faucet, and turn it on, releasing the water. Next, turn all the faucets inside the house to the “on” position, and flush all toilets. This will get rid of most of the water, but there will still be a small amount left. To get rid of it, you will use an air compressor to blow the remaining water out of the lines.

Blowing the Lines Out

Go back inside, and close all the faucets you turned on. Now, return to your low point faucet. Attach the air compressor to it with approximately 70 pounds of pressure. Once it builds up, you will return to the inside of the home. Once again, you will turn the faucets on. Always turn the hot water on first, then the cold.

For appliances, such as dishwashers and washing machines, you will need to turn them on using the hot cycles. Now, it’s time to take care of the toilets by opening the shutoff valves. Once this is done, pour a generous amount of antifreeze into each toilet bowl and tank along with all sink and bathtub/shower drains.

Watch this YouTube video to help guide you through the process.

Frequently Asked Questions

Here are some other questions you may have in relation to your pipes and winter:

Do Underground Water Pipes Freeze?

Underground water pipes do freeze. This is why it is so important to take the proper measures to insulate them. Even if you bury them beneath the frost level, there is still a chance your pipes could freeze.

At What Temperature Do Underground Water Pipes Freeze?

We all know that water freezes at 32 degrees. However, when the outside temperature reaches 32 degrees Fahrenheit, there is no need to worry about your water pipes freezing. This is because the pipes encasing the water will not be as cold as the surrounding atmosphere, especially if they are underground.

Instead, according to Hope Plumbing, underground water pipes freeze when the temperature reaches at least 20 degrees.

How Quickly Can Pipes Freeze?

Pipes do not freeze as quickly as you would imagine. The temperature must remain at or below 20 degrees Fahrenheit for a minimum of six hours straight before they will freeze.

How Deep Should You Bury a Water Line to Keep it from Freezing?

The depth at which you should bury your water line to keep it from freezing will vary, depending on where you live. For example, the frost line in Louisiana will be shallower than the frost line in Ohio. Find out what the frost level is for your area by consulting the National Weather Service.

You will need to bury your water lines at least this deep. However, it is not always possible to bury them below the frost level. High water tables can prevent you from digging that deep. Other concerns could be gas lines, public sewer systems, and underground utility obstructions.

What is the Best Pipe to Use for Underground Water Lines?

High-Density Polyethylene pipes are the best for underground water lines. Not only are they non-toxic and give off no taste, but they are also resistant to cracks and corrosion.

In Closing

Frozen and busted pipes can be a nightmare. Instead of sitting back and hoping for the best, take the above steps to insulate your buried water lines and prevent problems. If you have more questions about winterizing your home, check out these other helpful tips on our blog:

How To Insulate Single-Pane Windows [4 Methods To Try]

9 Types Of Thermal Insulation You Should Know

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