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How to Run Plumbing to a Detached Garage or Shed

August 9, 2023

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If you learn how to run plumbing to a detached garage or shed, you can create a world of possibilities! A utility sink in either space makes it easier to clean lawn care equipment and paint brushes. Renovating either space with a bathroom and kitchen can also allow you to create an additional dwelling unit. Where legally allowed, you can then earn an income or have a family member move in!

How to run plumbing to a detached garage or shed:

  • Create your plans
  • Obtain permits
  • Dig needed trenches
  • Lay pipes
  • Connect fixtures
  • Install ventilation
  • Test pressure
  • Backfill
  • Connect to sewer systems
  • Schedule inspections

Obviously, this is just a quick rundown of what’s needed to run plumbing to a detached garage or other outbuilding. Also, a professional plumbing contractor can make quick work of this project and ensure it passes inspection. However, if you want to try at least some steps yourself, check them out in more detail.

how to run plumbing to a detached garage

How to Run Plumbing to a Detached Garage or Shed

Running plumbing to a detached garage or shed starts with proper planning for bathroom plumbing! Don’t just run to the hardware store, buy some pips, and start digging. Also, remember that you need to obtain the necessary permits and schedule inspections. Here's a general overview of the process:


  • Determine the purpose of the plumbing (e.g., bathroom, sink, utility area) and what fixtures you'll need.
  • Check local building codes and regulations regarding plumbing installations for detached structures. This includes codes for any particular purpose such as for an additional dwelling unit.
  • Decide whether you want to install a separate septic or sewage system or connect to an existing one.
  • Ensure you note the layout of the new fixtures in your garage or other outbuilding. This helps determine how much pipe and other materials you’ll need.
  • When choosing fixtures, remember that they need to coordinate with each other. For instance, a faucet should be long enough to reach over a sink edge!

Obtain Permits

Contact your local building department to inquire about necessary permits and regulations. Remember that you’ll need to obtain the required permits before starting any work to ensure compliance with local codes. This process can sometimes take weeks, so be sure you plan accordingly.

Gather Materials

Purchase the appropriate plumbing pipes (PVC, PEX, or copper), fittings, valves, and fixtures. Don't forget tools like pipe cutters, wrenches, soldering equipment (if using copper), and pipe glue (if using PVC). Also, you’ll probably want to buy more than you need, in case of mistakes when cutting. You also don’t want to be in the middle of a project and find out that the store is out of stock on certain items!


Dig a trench from the main water supply and sewage lines to the location of the detached garage or shed. Ensure the trench is deep enough to protect the pipes from freezing and damage. Check local frost line depths.

Lay conduit for protecting electrical lines, if necessary. Your permitting office will note these regulations. If you’re not sure they require conduit, consider installing it anyway. This means extra protection for those lines and wires.

Lay Pipes

To lay pipes, install the main water supply line from your main water source to the garage or shed. Use the appropriate pipe type for your needs (PEX is often easier for DIY installations). Install drain pipes for sinks, toilets, or showers, ensuring proper slope for drainage. Connect the pipes using appropriate fittings, glue (for PVC), and clamps (for PEX).

Connect Fixtures and Install Ventilation

Install fixtures such as sinks, toilets, showers, or utility sinks according to the manufacturer's instructions. Connect the fixtures to the water supply and drain lines.

Ensure proper ventilation for the plumbing system to prevent airlock and sewer gas buildup. Install vent pipes that extend above the roofline.

Pressure Testing

After installing the plumbing system, conduct pressure testing to ensure there are no leaks. Close off all fixtures and pressurize the system to check for any drops in pressure.

Backfill and Cover

Once the plumbing system passes pressure testing, backfill the trench with soil, ensuring no sharp objects can damage the pipes. If you've installed electrical conduit, make sure it's properly protected and covered.

Connect to Sewer System (if needed)

If connecting to a municipal sewer system, consult with the local utility department for proper procedures and obtain necessary permits. Install the appropriate connections and pipes to connect to the sewer system.


Contact the local building department for required inspections at various stages of the plumbing installation. Don’t overlook this step as an inspection releases your permits. Without a proper inspection, you might face fines from the city. Also, it’s difficult to sell a home without inspections for DIY projects.

Once you’ve completed all these steps, you can add finishing touches to your outbuilding. This includes any interior work, such as walling, flooring, and fixture installation. Also, don’t forget to maintain the plumbing as needed over the years. This includes checking for leaks and insulating the pipes against freezing.

how to run plumbing to a detached garage

Can I Run Plumbing to My Shed?

In most cases, you can run plumbing to a shed. However, there are a few factors to consider before tackling this project:

  • Check with your local building department about permits, codes, and regulations that apply to running plumbing to a shed. Some areas might have specific requirements for detached structures.
  • Determine the purpose of the plumbing in the shed. Are you planning to install a bathroom, a sink, or a utility area? This will help you plan the layout and choose the appropriate fixtures. You’ll also need to consider your budget!
  • Consider how you will provide water to the shed. You might need to extend the existing water line from your main house. Ensure that the water supply is adequate for your needs.
  • You'll need a way to drain wastewater from the shed. Determine whether you'll connect to an existing sewer line, septic system, or install a separate sewage system.
  • Choose the appropriate pipe material for the plumbing system. PEX and PVC are commonly used for water supply lines, while PVC is often used for drain lines. Copper can also be used for water supply lines. Once you’ve chosen a material, you can add their expense to your budget.
  • If you live in an area with cold weather, you'll need to properly insulate pipes to prevent freezing. Additionally, plan to protect the pipes by burying them and using conduit if necessary.
  • Proper ventilation is crucial to prevent airlock and sewer gas buildup. Install vent pipes that extend above the roofline to ensure proper airflow.
  • Plan the layout for fixtures such as sinks, toilets, and showers. Make sure you have the necessary space and connections for each fixture.
  • Consider future maintenance and repairs. Ensure that the plumbing system is accessible and that shut-off valves are installed for each fixture.

A Word From Our Professional Plumbing Crew

Here at Princeton Plumbing Pros, we hope we explained how to run plumbing to a detached garage. If you’re in the area and this project is beyond your expertise, call our Princeton plumbing contractors. We offer a wide range of plumbing services including installation and repairs. To find out more about the plumbing services you need to have done, contact us today.


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