Both the IPC and IRC state that all water lines as well as sewer lines must be a minimum of 12 inches below grade, i.e., a foot underneath ground level.
Typically, water lines are buried at a depth ranging from 18 inches to 5 feet, depending on various factors such as local climate, soil conditions, and the type of water system in place.
The top of the pipe should be buried not less than 1 foot (0.3 m) below the frost line. In those locations where frost is not a factor, the depth of cover should be not less than 2- 1/2 feet (0.8 m) to prevent mechanical damage. Pipe should be buried below the frost line when entering streams and other bodies of water.
The International Plumbing Code states that “Exterior water supply system piping shall be installed not less than 6 inches (152 mm) below the frost line and not less than 12 inches (305 mm) below grade.” Above the frost line, the ground can heave up, shifting whatever is in it or freezing the pipes' contents.
Pipe for conveying liquids susceptible to freezing should be buried no less than 12" below the maximum frost level. Permanent lines subject to heavy traffic should have a minimum cover of 24". For light traffic, 12" to 18" is normally sufficient for small diameter pipe (typically < 3" diameter).
A service lateral installed in a PVC conduit under the backyard lawn must be buried at least 18 inches (457 mm) deep. Many utility companies require the service lateral to be installed in conduit.
High-density polyethylene (HDPE) pipe is a good choice for underground water lines because of how the pipe is connected. Rather than using joints, which can leak, or glues and cement, which can degrade over time, HDPE pipe is connected via plastic fusion.
The standard depth for water lines in the U.S. is around 36 inches, but this can vary from location to location.
Even buried, underground water pipes can be subject to freezing.
It is recommended to use a 'blank cap end' (made from plastic or rubber) with a purpose-made hole with a grommet to allow the water pipe to pass through. The water pipe should be laid at depth of 750mm (minimum) to 1350mm (maximum). Trenches should be lined and backfilled with sand or soft earth, not rubble.
Running a PEX line underground is beneficial because of the pipe's flexibility, temperature resistance, and lack of a need for multiple connections along its length. In areas with aggressive soil or water conditions, plastic or brass PEX fittings are recommended.
When you are digging the trench for your new waterline, be sure the waterline is 12-inches below the local frost depth, but in no case less than 2 feet underground.
For instance, residential sewer line depth ranges from 18 to 30 inches. However, city sewer line depths are different. Your city's sewer lines must always be deeper than the deepest residential pipe to allow waste to flow downhill. As such, these lines can go as deep as needed.
Eighteen to 24 inches is fine in most cases.
Perhaps the water pressure in your house isn't great or your water supply isn't healthy. If you find yourself in either of these situations, know that it is possible to replace a water main – the main pipe that supplies your water – entirely by yourself. You can also save yourself a lot of money in the process.
Generally, this clause requires a minimum depth of 300 millimetres unless the water service is subjected to vehicle loading which would requires a greater depth of between 450 millimetres and 750 millimetres dependant on the above ground surface. other services including gas or electrical and drainage pipes.
Your water line must be buried at least 12 inches below the frost line to meet local code requirements.
The Lifespan of a Water Line
The mainline provides homes, particularly within a suburban or urban housing development, with running water. Typically, main water line pipes last decades. Some experts estimate that they last around 70 years, though this can vary from development to development.
You should budget anywhere from $5 to $12 per linear foot to dig a trench or $13 to $40 per linear foot for major projects.
Adding drainage to a backyard does not have to be a complicated project. One drainage solution might be installing dry-wells in the areas that tend to get the most water. A dry well is simply a deep hole filled with gravel to allow water to reach a more permeable soil.
It's not just a pipe dream, because you can still do it on your own! Running water lines in your house comes down to knowing what tools you'll need, and how to use them to repair or install brand new pipes.
PVC and CPVC have more strength and durability than PEX because they are more rigid, making them better suited to outdoor applications where the piping may be subjected to trauma.
Microtunneling is a trenchless method that involves the use of a micro tunnel boring machine to excavate a tunnel underground. The machine is controlled remotely and uses a pipe-jacking system to install the new pipe. Microtunneling is commonly used for the installation of sewer and water pipelines.
Spoke with my colleague: California Plumbing Code 2007 Edition (news to me): Section 609.1 states: Minimum cover shall be 12" below finish grade or minimum 12" below the local frost depth. So, 18" below finish grade will be fine and I know on occasion, you get frost in Danville (rarely).