What Size PVC Pipe Should be used for a Gutter Drain?

If you’re planning on installing a PVC gutter drain in your yard, you’ve probably noticed the large variety of PVC pipe to choose from. Selecting a pipe with a small diameter allows you to dig a much smaller trench, but it’s likely to not have the capacity to handle rainwater and debris. PVC with a larger diameter is effective at whisking rainwater away, but would require you to dig up much of your yard to accommodate it. Below we'll cover the best size pipe for your gutter drain, as well as other factors to consider when it comes to proper installation.

The standard size for PVC pipe when installing a gutter drain is 4 inches in diameter. This will allow for proper drainage during rainstorms and will reduce the likelihood of debris clogging the line. In some instances, a 3-inch diameter PVC pipe may be appropriate, but be sure to check with your local building department for their guidelines prior to installation. Things to consider when choosing the size include the length of run, how much water will be captured by that specific gutter, and the gutter sizing.

While the diameter of your PVC pipe might be the biggest question you have about installing a gutter drain, there are several other important factors to consider. As you prep your materials and design your plan, take into account the following:

• Rigid PVC Pipe - This is the most commonly used PVC pipe for gutter drains. The nonperforated interior allows for rainwater and debris to pass through easily. However, it can be more challenging to install, because the rigid design won’t be able to bend around obstacles like root systems or irrigation lines.
• Corrugated Pipe - Many people wonder if corrugated pipe, which can easily be bent and stretched, can be used in gutter drains. While some localities may allow it, corrugated pipe is prone to catching debris inside and is not as effective as PVC pipe. This is a commonly used material for this application.

• Thin Walled PVC Sewer & Drain Line - This piping is also popular for gutter drain. It is lighter weight and somewhat easier to manipulate than regular white schedule 40 PVC. It's important to note that this type of piping is thin walled. It will work, but, depending on what will be buried over this pipe, it could collapse under weight. This piping is the same O.D. as regular sch 40.

It’s important to bury your gutter drain deep enough to avoid damage from hard freezes and heavy traffic. Check your local codes to understand your location's fost line. In the south, 3 to 6 inches may be all that is needed. In Northern locations, 4 feet more more may be needed to keep the pipe from bursting in winter. If the area receives heavy traffic, consider a trench that is at least 24 to 36 inches deep, even in low frost line areas.

If you’re installing a gutter drain, you probably understand the importance of keeping water from pooling near your foundation. Your PVC pipe should extend at least 4 to 6 feet away from the exterior of your home. If your property size allows for it, a 10-foot gutter drain is ideal for dispersing water away from your home. Anything longer could be more challenging to clean or repair if needed unless a specific application calls for it. You can run gutters 20 - 30 feet for under patio or structure situations.

Your gutter drain relies on gravity to move the water away from your home’s foundation. While it makes sense that a gutter drain traveling uphill will not have the desired effect, a horizontal drain may not be effective either. Professionals recommend a quarter-inch slope for every ten feet of PVC you install.

Before you mark the path for your gutter drain, it’s important to know where your cables and pipes are located on the property. Digging near these lines could be dangerous to you and your neighbors. If you’re unsure, contact your local cable and gas companies to mark the lines prior to installation.

While this information is a good guideline for planning out your gutter drains, you’ll need to check with your local municipality before starting any project. Your municipality designs building codes that take into account the soil, climate, and topography, which could differ from the measurements suggested here.

• Trencher
• 4 in. diameter Sch 40 (white) PVC pipe
• Construction mark spray
• Spout adapter
• PVC connectors / fittings
• Tape measure

1. Mark the path—Use the construction spray to mark a path for your gutter drain, taking into account your existing irrigation system and landscaping.
2. Dig the trench—Use your trencher to dig approximately 16 in. deep from the downspout to the location you plan to have the water drain.
3. Remove debris from the trench—Rocks, roots, and other debris could damage the PVC pipe. Remove any obstructions and smooth out the bottom of the trench before installing the pipe.
4. Connect your spout adapter and PVC gutter drain—Begin by connecting your spout adapter to the end of the gutter. Then connect the PVC pipe to the adapter.
5. Connect your PVC through the end of the trench—Lay as much PVC as you’ll need to reach the end of the trench, connecting with appropriate fittings.
6. Fill the trench—Use gravel to fill the trench, making sure each section of PVC is supported underneath. If a section of pipe is not supported, shovel some dirt underneath it.
7. Pack the dirt—Add dirt to the top of the trench and pack it to avoid erosion.

Gutter drains are an effective way to move rainwater away from your house, and installing one may be easier than you think. While it’s always important to check local building codes to make sure you’re complying with their guidelines, most PVC gutter drains use 4 in. diameter pipe. However, that’s not the only factor to consider. You may want to opt for rigid PVC which is less likely to clog, and make sure your gutter drains are at least 12 inches deep or more to avoid damage from freezing and heavy traffic. To keep water away from your foundation, create a gutter drain that is at least 4 to 6 feet long, as well. Following these guidelines will help keep your home and yard puddle free during rainy season.