How Deep Are Residential Water Lines Buried? Keep It Below the Frost Line!!

Many cases of water pipe freezing, damage during planting or digging, and exploding (due to excessive expansion) are experienced every year. These all are mostly associated with one common string: inappropriate residential water pipe burial depth. 

So, how deep are residential water lines buried? According to IPC, the water lines should be buried at least 6 inches (152 mm) below the frost line and 12 inches (305 mm) below grade.

The following segments cover the factors to consider while burying a water pipe. At the same time, it unfolds all the queries regarding this matter. Read on to learn everything about the depth of the water line burial. 

How Deep Should A Residential Water Line Be Buried? Facts Explained

The standard depth of the water line burial is not less than 6 inches below the frost line and 12 inches below grade. Here, below grade means the area which is below the ground level. However, these numbers are not constant; geographical position determines the water pipes’ burial depth.

To move further, you must understand the frost line and how it determines the depth of the water line. The frost line is basically the deepest point of the ground at which the frost occurs, and the water freezes. It is very important that the water line should be buried below the frost line to prevent freezing.

Now, the frost line is not the same in different states and can be drastically different. For example, the frost line in Minnesota is 80 inches, and in Texas, it is 10 inches. Hence, the appropriate water line burial depth will differ in these states. 

Let’s break this whole thing to you, considering the frost line. Suppose your region has 24 inches of frost depth. Then, the water pipe should be buried so that the top surface remains at least 30 inches below grade. This 6-inch buffer actually protects the pipe from freezing and also from soil moisture.

By the way, if you want to be more safe, then you should follow the 12-inch below grade. So, bury your water pipes under 36 inches of surface.

[Note: Always call 811, the national phone number in the USA, before you dig for the water line. And consult them if there is any electricity or gas supply line present so that you do not end up damaging them.]

Factors to Consider While Determining The Water Line Burial Depth

You cannot simply put the underground water line without measuring the appropriate depth. To determine the burial depth of the water line, you must consider certain facts. 

i. Always Check the Frost Line

As stated already, check the frost line in your area and then determine the water line burial depth accordingly. But make sure you bury the water line at least 12 inches below grade. 

ii. Get in Touch with the Municipality

Contact the municipality beforehand; do not just start digging blindly. Ask for their recommended water pipe burial depth and dig accordingly. Every city has different regulations and building codes. So, it is better to ask the municipality before you install the pipe. 

iii. Know the Location of the Utility Pipes

Get a good idea about the utility supply line’s whereabouts. You must keep at least 300 mm between the utility and water pipes. So, make sure you know the locations of the other supply pipes and place the water pipe accordingly. You can call 811, for that matter. 

Why is It Important to Maintain the Appropriate Water Line Depth?

Why is It Important to Maintain the Appropriate Water Line Depth?

There are several reasons to keep the water supply underground within a certain depth. But the three main reasons are stated  below:

1. Prolonging the Lifespan of Water Line

It is important to bury the waterline at a certain depth to prolong its lifespan. If not kept underground, water lines can be exposed to susceptible damage: wear or tear. Also, during shallow digging for planting or yard work, these pipes can face accidental damage. 

2. Prevent Water From Freezing

The most important reason to place a water pipe underground is to prevent it from freezing. Water pipes can freeze if the temperature goes below 20 degrees Fahrenheit. Freezing can lead to expansion or split in the water line, resulting in replacement hassle. And we all know how much these replacements can cost you.

Frozen pipe blocks the water flow of your house, and the suffering is well known to everyone. And once the pipes thaw, the scenario can get much worse. Pipes after being frozen when thaw, a sudden water pressure can come through and will flood your home. 

Related Questions

So far, you know the necessary basics about the appropriate depth to bury water supply pipes. Yet here in this segment, we will cover the common queries people ask about water line burial depth. 

Q: Which Pipe Should you pick from the underground water line? 

Both PVC and PEX pipes will work great as they can withstand the underground pressure. These pipes are resistant to corrosion as well. Copper pipes also work great as they are leakage-proof and corrosion-resistant. 

Q: What Size Pipes are suitable for water lines?

The main pipe from the street to the house should be 12 to 43 mm thick. The individual components should be ½ inch, and the supply pipe should be ¾ inch. 

Q: What can you do to prevent the underwater pipe from freezing? 

To prevent the underwater pipes from being frozen, you should insulate them properly. There are different types of insulators available in the market. Mineral wool insulation, fiberglass, rubber, foam, and spray foam are some widely used insulators that will work great. 

Conclusion

Burying the water pipe in a certain depth is necessary to ensure its longevity and to prevent freezing-related hassles. Also, burying water pipes in an appropriate depth is necessary to prevent hampering the other utility lines. However, the appropriate depth can be different for each state. 

You must consider contacting the municipality without considering any particular length to be appropriate. Following the building code of your region, you can get a brief idea of the ideal water pipe depth. 

Reference

  • https://codes.iccsafe.org/content/IPC2018/chapter-3-general-regulations
  • https://worldpopulationreview.com/state-rankings/frost-lines-by-state

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