How to Run Plumbing to a Detached Garage

how to run plumbing to a detached garage

If you’re looking to add some additional plumbing to your home or need access to water and waste outside of the main structure of your home, running plumbing to a detached garage is a great way to go. Installing plumbing to a detached garage isn’t as complicated as it may seem; it just needs to be done with care and precision. In this article, we’ll give you a step-by-step guide on how to run plumbing to a detached garage, what materials you will need, and provide answers to common questions such as “Will I need permission to install plumbing pipes between the house and the garage?” and “What type of fittings should be used for plumbing connections between the house and a detached garage?” So, let’s get started!

Materials Needed

When running plumbing for a detached garage, it is important to have the proper materials on hand. You will need a variety of pipes and fittings, such as PVC pipes, PVC fittings, solder, flux, a hacksaw or tubing cutter, a utility knife, and Teflon tape. You will also need a power drill for drilling holes into walls, and a recip saw for cutting through material. Finally, you will need a variety of tools to help complete the job, such as a wrench, pipe wrench, hammer, and pliers. Having these materials will make it easier to run plumbing to your detached garage and complete the job successfully.

Step 1: Plan the Plumbing Design

Before attempting to run plumbing to your detached garage, it is important to take some time to plan out a detailed design. First, assess the size and layout of your garage. Next, consider the type of plumbing that you need to install. This could include running cold water, waste, or natural gas lines. Once you have a better idea of the type of plumbing to include, you can begin to map out the location for the pipes and fixtures and plan the route for the new plumbing lines to reach your detached garage. Planning the plumbing design ahead of time will help to ensure a successful installation.

Step 2: Dig the Trench

The next step in how to run plumbing to a detached garage is to dig a trench between the main house and the garage. You will need to dig a trench of a depth appropriate to your local building codes and the type of pipe you are using. If you are using a plastic pipe, the trench will need to be deep enough to accommodate a foot of gravel at the bottom. The width of the trench should be large enough to fit in the pipe you are using, as well as any fittings and fasteners. It is important that the trench is dug straight, so that the pipe will fit properly when installed. Once you have finished excavating the trench, it is important to check the depth of the trench with a tape measure to ensure that it is the appropriate depth before continuing.

Step 3: Install the PVC Pipe

Once you have determined the route for the pipe, you can begin installing the pipe. Make sure that you measure the distances between the locations where the pipes will be attached to ensure that they are the correct length. You will need to purchase PVC pipes in the desired diameter and length to fit the project. Also be sure to buy the necessary connectors and fittings to join the pipes.

Next, attach the pipes to the fittings and connectors, starting at the water source and then to the detached garage. Make sure to secure the pipes with insulation, and apply a sealant to the fittings and connectors to keep the pipes watertight. Use a level and plumb bob, if necessary, to ensure the pipes are properly aligned. Once all the pipes are installed, turn on the water at the source to check for any leaks. If there are no leaks, your plumbing is ready for use.

Step 4: Install the Fittings

Once the pipes have been laid, you will need to attach the fittings. Depending on what type of pipe you are using, you will need to choose the correct fittings for the job. For example, if the pipe is made of copper, you will need copper fittings. Make sure to provide a good seal when installing the fittings. If a fitting is not securely attached, it could cause water to leak. Make sure to use Teflon tape or other thread sealant to help create a good seal. When all fittings are securely attached and tested for leaks, you are ready to move on to the next step.

Step 5: Install the Backflow Preventer

Once all the tubing and other plumbing components have been installed, it’s time to install the backflow preventer. This is an important device that helps to protect your plumbing system against contamination. To install it, start by loosening the compression nuts on the backflow preventer. The compression nuts should be attached to the supply lines. Next, align the hole in the backflow preventer with the hole in the wall and screw the bracket into the wall. Finally, tighten the compression nuts and attach the backflow preventer to the bracket. Your backflow preventer is now ready to use.

Step 6: Connect the Pipes to the House

Once the pipes are in place in the detached garage, it is time to connect them to the house. Depending on the type of pipe chosen, the connection may look different. If you have PVC pipes, you can use PVC glue to connect the pipes at the connecting points. If copper piping is used, you will need to connect the two pipes with solder. Make sure the connection is secure and leak-free before moving to the next step.

Step 7: Install the Shut-off Valve

Once all of the piping is in place, the shut-off valve should be installed at the end of the pipe. This valve will allow you to control the water supply to the garage. Before installing, make sure the valve is compatible with the existing water line and shut off the water supply. Once the valve is in place, turn the water back on and check for leaks. If everything is functioning properly, you have completed the plumbing to your detached garage.

Step 8: Test the Plumbing System

Now that you’ve run the plumbing from the main house to the detached garage, it’s time to test the system to ensure everything is working. Begin by turning on the water at the main house and the detached garage. Check for any leaks or drips, which if present should be tightened and sealed. Once any necessary repairs have been made, it’s time to fill the system and check for any leaks again. If the system passes all tests, the plumbing system is now fully functional and ready to be used.

Will I need permission to install plumbing pipes between the house and the garage?

Generally, if you’re installing plumbing between the house and your detached garage, you will need permission from your local building authority. This is due to plumbing being classified as a structural change and local laws relating to these changes may vary. To ensure that your plumbing is installed safely and in accordance with local regulations, it is important to contact your local building authority prior to beginning any work. This will ensure that you don’t run into any legal problems with your installation.

What type of fittings should be used for plumbing connections between the house and a detached garage?

Due to the nature of this project, using the correct type of fittings is essential. It is recommended to use compression fittings to connect two pipes together and ensure a durable connection. Additionally, the use of a threaded connector should be used to join the pipes to another piece of plumbing equipment such as a faucet, valve or other piece of plumbing hardware. Furthermore, it is also important to use pipe clamps to secure the pipes and prevent any leaks from occurring. When running plumbing from a house to a detached garage, it is essential to use these specific types of fittings to ensure that the system operates effectively and securely.


Installing plumbing to a detached garage can be a challenging job, but it is possible to do the work yourself with the right materials and a bit of knowledge. You need to plan the plumbing design, dig a trench, install the PVC pipes, fit the fittings, install a backflow preventer, connect the pipes to the house, installing the shut-off valve, and testing the plumbing system. Furthermore, you may need to seek permission from your local authority before carrying out some work. The best type of fittings to use for plumbing connections between the house and a detached garage are compression fittings.
Overall, plumbing to a detached garage can be a complicated project. However, with a basic understanding of the process, the right materials, and a bit of hard work it is possible to complete the job yourself.

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