How to Install a Dry Well: Step-by-Step Guide

How to Install a Dry Well: A Comprehensive Guide to Managing Stormwater Runoff

A dry well is an excellent solution for managing stormwater runoff from your roof gutters and downspouts. Instead of allowing water to pool near your home’s foundation or contribute to erosion problems in your yard, a dry well collects and disperses this water gradually into the surrounding soil. This guide walks you through the entire installation process, from initial planning and site selection through the final touches that bring your dry well system to full functionality.

Understanding the Purpose of a Dry Well

Before diving into the installation process, it’s important to understand what a dry well does and why it matters. A dry well serves as a collection basin for water drainage, particularly from roof gutters and downspouts. Rather than allowing water to flow directly into storm drains or pool around your home’s foundation, a dry well captures this water and allows it to percolate slowly into the surrounding soil. This natural infiltration process reduces erosion, prevents foundation damage, minimizes localized flooding, and helps recharge groundwater supplies. Installing a dry well is not just an aesthetic improvement—it’s a practical investment in your home’s longevity and your property’s drainage health.

Step 1: Dig the Hole and Trench

Selecting the Optimal Location

The first step in installing a dry well is choosing the right location. You should select a spot that is at least 10 feet away from your home’s foundation to ensure that water infiltration does not compromise your foundation’s integrity. Additionally, the location should be at least 3 feet from any property line to avoid drainage issues with your neighbors’ properties. Before you begin any digging, contact your local utility locating service by calling 811. This essential call ensures that public utilities mark the locations of underground infrastructure such as gas lines, electrical conduits, water mains, and sewer lines. These utilities must be clearly marked, and if they are directly underneath or too close to your proposed dry well site, you will need to select an alternative location for safety reasons.

Excavation Specifications

Once you’ve confirmed that your site is safe and utilities have been marked appropriately, you can begin the excavation process. Dig a hole approximately 4 feet wide and 4 feet deep at the dry well location. From the downspout to this hole, you’ll need to create a trench. Start by tunneling under any sidewalks using a long-handled shovel, then dig a trench that is one foot deep and 6 inches wide. This trench should slope gradually toward the main hole to encourage water flow in the proper direction.

Managing Excavated Soil

As you dig, shovel all excavated soil onto a tarp. This approach serves multiple purposes: it keeps your yard organized during the project, and more importantly, it allows you to preserve the soil for later use. If there is sod covering the area you’re working in, carefully remove it and set it aside separately. You’ll use this sod to cover the finished dry well installation, giving your yard a neat, completed appearance.

Step 2: Line the Hole

Installing Landscape Fabric

Once you’ve completed the excavation, the next critical step is lining the hole with landscape fabric. Purchase a 6-foot-long roll of quality landscape fabric and cut it to size. This fabric serves an important function: it acts as a barrier that prevents soil from clogging the drainage stones that surround the dry well. The better the quality and the longer the fabric, the more effectively it will function over time, ensuring your dry well remains permeable and functional for years to come.

Securing the Fabric

As you position the landscape fabric around the interior of the hole, leave enough fabric extending outside the hole so that you can fold it over and cover the stones completely after you’ve filled the hole. Once you have the fabric positioned with appropriate coverage, secure it in place using landscape staples. These staples prevent the fabric from shifting as you add stones and water, which could compromise the barrier’s effectiveness. Take your time with this step to ensure the fabric is taut and properly anchored.

Step 3: Set Up the Pipe

Selecting and Preparing PVC Materials

The piping system is the conduit through which water travels from your downspout to the dry well. Purchase 4-inch-diameter PVC pipe in sufficient length to reach from the end of your downspout to a point 14 to 16 inches into the hole. In addition to the straight pipe, you’ll need a 90-degree elbow fitting and a downspout adapter. These fittings allow you to connect seamlessly from your existing gutter system to the new drainage system.

Dry-Fitting and Positioning

Before permanently joining the components with PVC cement, perform a dry-fit—laying all the pieces together without adhesive to ensure the configuration works correctly. Position the pipe along the trench to verify that it slopes properly toward the hole and that all connections align well. This preliminary assembly helps you identify any issues before you commit the pieces together permanently.

Cementing and Adjusting

Once you’re satisfied with the layout, use PVC cement to glue all the pieces together securely. The cement creates a permanent, watertight bond between the pipe sections and fittings. If the end of the pipe extending into the hole is too long, you can trim it to the appropriate length using a saw. After the cement has fully cured according to the manufacturer’s instructions, carefully position the entire assembly in the trench, backfilling soil around the pipe as needed to hold it in place.

Step 4: Check the Pitch

Understanding Proper Slope

Water flows downhill, so the pipe must have a proper downward slope, or pitch, toward the dry well. This pitch ensures that water moves consistently toward the collection basin rather than pooling in low spots along the pipe. A gentle slope is often recommended, typically around one-quarter inch per linear foot, which is gradual enough to avoid forcing water to flow too rapidly while still maintaining consistent movement.

Adjusting for Correct Pitch

To achieve the correct pitch, adjust the amount of soil underneath the pipe. Add or remove soil as needed to create the proper slope. You can verify the pitch using a level, placing it on top of the pipe and adjusting until you achieve the desired angle. Take time to get this step right, as incorrect pitch can result in water pooling and the system failing to function effectively.

Finalizing the Pipe Installation

Once the pitch is set correctly, attach the downspout adapter to your existing downspout using stainless steel sheet metal screws. These screws create a secure attachment point between the new drainage system and your gutter system. The stainless steel resists rust and degradation, ensuring a long-lasting connection. After securing the adapter, complete the backfilling process by adding soil around the entire length of the pipe to stabilize it and restore the appearance of the trench.

Step 5: Install the Dry Well

Assembling the Dry Well Container

Most dry wells come as prefabricated containers that require assembly according to the manufacturer’s directions. These typically consist of a plastic barrel or basin with drainage holes already molded into the sides. Follow the specific assembly instructions provided with your dry well, as designs may vary among manufacturers. Once the basic assembly is complete, locate the drainage holes (typically 1.5 inches in diameter) and knock them out using a hammer. Additionally, locate one of the 4.5-inch ports and knock that out as well. These openings allow water to enter the container and permeate into the surrounding soil.

Creating the Stone Foundation

Before placing the dry well in the hole, create a foundation layer of drainage stone. Shovel a 6-inch-deep layer of washed 3/4-inch rounded stone into the prepared hole. This stone layer provides structural support for the dry well and facilitates water drainage. Rounded stones are preferable to angular ones because they allow for better water movement while the smooth surfaces prevent damage to the container.

Positioning and Backfilling

Carefully set the dry well into the hole and slide the open port over the PVC pipe coming from your downspout. This connection allows water collected from your roof to flow directly into the dry well. Make sure the dry well is centered in the hole, then continue adding washed stone around all sides until you reach the top edge of the container. This backfill of stone creates the permeable matrix that allows water to infiltrate into the surrounding soil.

Step 6: Complete the Installation

Installing the Lid and Emitter

Once the dry well body is in place and surrounded by stone, you need to prepare the lid. Use a reciprocating saw to cut a 4-inch-diameter hole in the plastic lid of the dry well. This opening accommodates the overflow pipe. Attach the lid to the barrel according to the manufacturer’s instructions. Take a length of 4-inch PVC pipe and glue an emitter fitting to the top using PVC cement. This emitter serves as an overflow point—if the dry well becomes completely saturated and cannot absorb water any faster, excess water exits through this pipe.

Setting the Emitter Height

Trim the overflow pipe to the appropriate length so that when it is glued to the lid, the top of the emitter sits exactly at ground level. This height ensures that overflow water, if it occurs, disperses across the surface of your yard rather than creating a flood or pooling in an unintended location. Precision in this measurement prevents future drainage problems.

Final Landscaping

With the dry well and overflow system in place, cover the entire installation with landscape fabric. This covering prevents soil from washing into the drainage area. Add the excavated soil back to cover the dry well, building it up to the original ground level. Finally, replace the sod you carefully preserved at the beginning of the project. This completes the installation and restores your yard to its natural appearance, with the dry well functioning invisibly beneath the surface.

Materials and Tools Needed

Tools Required for Installation

Successfully installing a dry well requires having the right tools available. You’ll need a shovel for excavation work, a long-handled shovel for tunneling under sidewalks, and a level to check the pitch of the trench and pipe. A measuring tape ensures accurate distances and depths, while a hammer is necessary for knocking out the drainage holes in the dry well. A reciprocating saw cuts the overflow hole in the lid, and stainless steel sheet metal screws are secured with a screwdriver or power drill. Consider also having a tarp available for managing excavated soil, and wear safety gloves and goggles throughout the project to protect yourself from sharp stones and soil.

Frequently Asked Questions About Dry Well Installation

Q: How far from my house should I locate the dry well?

A: Position the dry well at least 10 feet from your home’s foundation to ensure that water infiltration does not compromise the foundation’s structural integrity. This distance provides a buffer zone between water absorption and your home’s base.

Q: Why do I need to call 811 before digging?

A: Calling 811 activates the utility locating service, which marks underground infrastructure including gas lines, electrical lines, and water mains. Striking these utilities during excavation can be dangerous and costly, so this step is essential for safety.

Q: What type of stone should I use in the dry well?

A: Use washed 3/4-inch rounded stone. The rounded edges prevent damage to the dry well container and pipes, while the size allows for good water drainage while providing structural support.

Q: How do I know if my trench has the correct pitch?

A: Use a level placed on top of the pipe. Adjust the soil underneath until you achieve a gentle downward slope toward the dry well, typically around one-quarter inch per linear foot.

Q: What happens if the dry well becomes completely full?

A: The overflow emitter, which sits at ground level, allows excess water to disperse across the yard surface if the dry well cannot absorb water quickly enough during heavy rainfall.

Q: Can I install a dry well myself, or do I need a professional?

A: Many homeowners successfully install dry wells themselves if they follow proper steps and local regulations. However, if you’re uncertain about utility locations, soil conditions, or local drainage codes, consulting a professional may be wise.

Q: How long does a dry well installation typically take?

A: Most homeowners can complete a basic dry well installation in one to two days, depending on the distance from the downspout to the installation location and soil conditions.