DIY Dry Well: Build Your Own For Better Drainage

Aug 21, 2025 by Benjamin Cohen 49 views

Are you dealing with excess water in your yard, causing soggy spots or even flooding? A dry well might just be the solution you need! In this comprehensive guide, we'll walk you through the process of building a dry well, step by step, so you can effectively manage water runoff and keep your property dry and healthy. Dry wells are an environmentally friendly and cost-effective way to handle stormwater, and with a little effort, you can build one yourself. Let's dive in!

Understanding Dry Wells

Before we get into the nitty-gritty of building a dry well, it's important to understand what it is and how it works. Essentially, a dry well is an underground structure designed to collect excess water and gradually release it into the surrounding soil. Think of it as a subterranean reservoir that helps to prevent water from pooling on the surface. This is particularly useful in areas with poor drainage or heavy rainfall, where water tends to accumulate and cause problems.

How Does a Dry Well Work?

The basic principle behind a dry well is simple: it provides a large underground space for water to collect and then slowly percolate into the soil. The well is typically constructed as a pit filled with gravel, rocks, or a prefabricated chamber. Water is directed into the well through a pipe, usually connected to downspouts or a surface drain. Once inside the well, the water filters through the gravel or other fill material and gradually seeps into the surrounding soil. This process helps to replenish groundwater and prevents surface flooding.

The design of a dry well is crucial for its effectiveness. The size of the well, the type of fill material used, and the soil conditions all play a role in how well it functions. A properly designed and installed dry well can handle significant amounts of water, making it an invaluable tool for managing stormwater runoff.

Benefits of Building a Dry Well

There are numerous benefits to building a dry well on your property. Here are a few key advantages:

Preventing Flooding: This is perhaps the most significant benefit. By capturing and dispersing excess water, dry wells prevent water from pooling on your property, reducing the risk of flooding and water damage to your home and landscaping.
Improving Drainage: Dry wells are excellent for improving drainage in areas where the soil is compacted or doesn't drain well naturally. They provide a pathway for water to seep into the ground, preventing soggy spots and waterlogged soil.
Protecting Your Foundation: Excess water around your foundation can lead to serious structural problems. A dry well can help to divert water away from your foundation, protecting it from damage caused by moisture and hydrostatic pressure.
Reducing Erosion: When rainwater runs off quickly, it can carry away topsoil and cause erosion. A dry well helps to slow down the flow of water, reducing erosion and preserving the integrity of your landscape.
Replenishing Groundwater: By allowing water to seep back into the soil, dry wells help to replenish groundwater supplies. This is especially important in areas where water resources are scarce.
Environmentally Friendly: Dry wells are a sustainable way to manage stormwater runoff. They reduce the need for artificial drainage systems and help to filter pollutants from the water before it enters the ground.

Is a Dry Well Right for You?

Before you start digging, it's important to determine if a dry well is the right solution for your specific situation. Consider the following factors:

Soil Type: The soil around your property needs to be able to absorb water at a reasonable rate. Sandy or gravelly soils are ideal, while clay soils drain much more slowly. A percolation test (more on this later) can help you determine the drainage rate of your soil.
Water Table: The water table is the level below which the ground is saturated with water. If the water table is too high, a dry well won't function properly. You'll need to ensure that the bottom of the dry well is well above the water table.
Local Regulations: Some municipalities have regulations regarding the construction of dry wells. Check with your local authorities to ensure you comply with all applicable codes and permits.
Size and Location: The size of your dry well will depend on the amount of water you need to manage. The location should be chosen carefully to maximize its effectiveness and minimize any potential impact on your property or neighboring properties.

Planning Your Dry Well Project

Now that you have a good understanding of dry wells, let's move on to the planning phase. This is where you'll assess your site, determine the size and location of your dry well, and gather the necessary materials and tools. Careful planning is essential for a successful dry well project.

1. Assess Your Site

Start by evaluating your property to identify the areas where water accumulates. These are the areas where a dry well would be most beneficial. Consider the following:

Areas of Standing Water: Where do you typically see puddles or standing water after a rain? These are prime candidates for dry well locations.
Downspout Outlets: Downspouts are a major source of water runoff. Connecting a dry well to your downspouts can help to manage this water effectively.
Sloping Areas: If your property slopes towards your house, a dry well can help to intercept water runoff before it reaches your foundation.
Soil Conditions: As mentioned earlier, soil type is a crucial factor. Perform a percolation test to determine how quickly your soil drains. This test will involve digging a hole, filling it with water, and measuring how long it takes for the water to drain away. This information will help you determine the size and design of your dry well.

2. Determine the Size of Your Dry Well

The size of your dry well will depend on several factors, including the amount of rainfall in your area, the size of the drainage area, and the soil's drainage capacity. A general rule of thumb is to calculate the volume of water you need to manage and then design the dry well to hold that volume.

To estimate the water volume, you can use the following formula:

Volume (cubic feet) = Drainage Area (square feet) x Rainfall (inches) x Runoff Coefficient

Drainage Area: This is the area that drains into the dry well, such as your roof, driveway, or lawn.
Rainfall: Use the average rainfall for a significant storm in your area. You can find this information from local weather data or online resources.
Runoff Coefficient: This is a factor that represents the percentage of rainfall that becomes runoff. It varies depending on the surface type. For example, a roof has a high runoff coefficient (around 0.9), while a lawn has a lower coefficient (around 0.2).

Once you've calculated the volume, you can use this information to determine the dimensions of your dry well. Remember to factor in the void space within the fill material (gravel, rocks, etc.). A good rule of thumb is to assume that the void space is about 40% of the total volume.

3. Choose a Location

Selecting the right location for your dry well is critical for its effectiveness and longevity. Keep the following considerations in mind:

Distance from Buildings: Locate the dry well at least 10 feet away from your house and any other buildings to prevent water from seeping into the foundation.
Proximity to Downspouts: If you're connecting the dry well to downspouts, choose a location that's convenient for piping.
Underground Utilities: Before you dig, call your local utility companies to locate any underground lines (gas, electric, water, etc.). Digging near utilities can be extremely dangerous.
Soil Conditions: Choose a location with well-draining soil. Avoid areas with heavy clay or compacted soil.
Slope: If possible, locate the dry well in a low-lying area where water naturally tends to collect.

4. Gather Materials and Tools

Here's a list of materials and tools you'll likely need for your dry well project:

Shovel or Excavator: For digging the pit.
Wheelbarrow: For moving soil and materials.
Gravel or Crushed Stone: For filling the well (typically ¾-inch to 2-inch size).
Filter Fabric: To line the pit and prevent soil from clogging the well.
Perforated Pipe: For directing water into the well.
Solid Pipe: For connecting the downspouts to the perforated pipe.
Pipe Fittings: Elbows, connectors, etc., as needed.
Level: To ensure proper slope and drainage.
Measuring Tape: For accurate measurements.
Safety Gear: Gloves, safety glasses, and sturdy boots.

Step-by-Step Guide to Building Your Dry Well

Now that you've planned your project and gathered your materials, it's time to start building! Follow these step-by-step instructions to construct your dry well:

Step 1: Dig the Pit

Using a shovel or excavator, dig a pit to the dimensions you determined in the planning phase. The pit should be deep and wide enough to hold the calculated volume of water. Remember to dig at least 10 feet away from your house and any other buildings.

Step 2: Line the Pit with Filter Fabric

Line the entire pit with filter fabric. This fabric will prevent soil from entering the dry well and clogging the gravel. Make sure the fabric extends beyond the edges of the pit so you can fold it over the top later.

Step 3: Install the Perforated Pipe

Lay the perforated pipe along the bottom of the pit. The pipe should be sloped slightly downward, away from the inlet, to encourage water to flow through the entire well. Connect the perforated pipe to a solid pipe that will run to your downspouts or surface drain.

Step 4: Fill the Pit with Gravel

Fill the pit with gravel or crushed stone. The gravel should be clean and free of debris. Fill the pit to within a few inches of the top.

Step 5: Fold the Filter Fabric Over the Gravel

Fold the excess filter fabric over the top of the gravel. This will create a barrier that prevents soil from entering the well while still allowing water to seep in.

Step 6: Cover with Topsoil

Cover the top of the dry well with topsoil. You can then seed the area with grass or plant other vegetation. The vegetation will help to stabilize the soil and blend the dry well into your landscape.

Step 7: Connect the Downspouts

Connect the solid pipe from the dry well to your downspouts or surface drain. Make sure the connections are secure and watertight. You may need to use pipe fittings (elbows, connectors, etc.) to make the connections.

Maintaining Your Dry Well

Once your dry well is built, it's important to maintain it properly to ensure it functions effectively for years to come. Here are some maintenance tips:

Regular Inspections: Inspect your dry well regularly, especially after heavy rains. Look for signs of clogging or other problems.
Cleaning: Periodically clean out any debris that may have accumulated in the dry well. This may involve removing the topsoil and filter fabric and cleaning out the gravel.
Preventing Clogging: To prevent clogging, make sure your downspouts have screens or filters to catch leaves and other debris. You can also install a catch basin or sediment trap upstream of the dry well to filter out sediment.
Professional Maintenance: If you notice any serious problems, such as slow drainage or standing water, consider hiring a professional to inspect and maintain your dry well.

Troubleshooting Common Problems

Even with careful planning and maintenance, you may encounter some problems with your dry well. Here are some common issues and how to address them:

Slow Drainage: If your dry well is draining slowly, it may be clogged. Try cleaning out the gravel or replacing the filter fabric. If the problem persists, you may need to excavate the dry well and replace the fill material.
Standing Water: If you notice standing water in or around your dry well, it could indicate a serious clog or a problem with the soil's drainage capacity. Inspect the dry well for obstructions and consider performing a percolation test to assess the soil's drainage rate.
Overflowing: If your dry well is overflowing, it may be too small for the amount of water it's receiving. You may need to expand the size of the dry well or install additional drainage measures.
Erosion: If the soil around your dry well is eroding, it could be due to excessive water flow or improper installation. Stabilize the soil with vegetation or erosion control measures.

Conclusion

Building a dry well is a fantastic way to manage stormwater runoff and protect your property from water damage. It's a cost-effective, environmentally friendly, and relatively straightforward project that you can tackle yourself. By understanding the principles of dry wells, planning your project carefully, and following the step-by-step guide, you can create a dry well that effectively manages water and keeps your property dry and healthy. Remember to maintain your dry well regularly and address any problems promptly to ensure its long-term effectiveness. So, guys, get out there and build your own dry well – your yard will thank you for it!