How to Build a Dry Well

Co-authored by Eric McClure

Last Updated: October 21, 2021 Approved

A dry well is an excellent way to divert water runoff from your roof away from your home and yard. Essentially, a dry well takes the water coming off of your home when it rains and drains it away from your home to a tank and gravel pit that is designed to handle large amounts of water. To build a dry well, you’ll need PVC piping, a drain tank, and an adaptor for your downspout. You’ll also need a lot of loose gravel and unwoven landscape fabric to line your ditch and fill your well. Before you start digging, contact your local government to check your yard for utility lines that may potentially interfere with your well system.

Part 1

Part 1 of 4:

Selecting a Location for Your Well

1
Find the gutter downspout closest to the soggiest part of your yard. After it rains, note which part of your yard is having the most trouble with drainage. Take a stroll around your yard after a heavy rain and look for the area retaining the most water. Typically, the flattest section of your yard will have the most trouble with drainage if there aren’t any valleys.^{[1]
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- Dry wells are designed to keep water from building up near your home when it rains. You typically want to install your dry well near the downspout that has the biggest issue with water pooling up around it.
2
Position the dry well 10 feet (3.0 m) from the downspout. You need to place your dry well at least 10 feet (3.0 m) away from your home to ensure that you aren’t soaking the ground around your basement or foundation. The water may seep at least 25 feet (7.6 m) away from your well, so try not to aim it towards a neighbor’s home.^{[2]
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Warning: In many countries and states, it is actually illegal to place a dry well within 10 feet (3.0 m) of a wall or public property.

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3
Ensure the excess water will lead away from your home. In the event that your dry well floods, you’ll want the excess water to pool up and drain away from your home. Look for a direction away from your spout with a slight decline away from your home. Choose a path that doesn’t lead to your walkway or driveway.^{[3]
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- Ideally, your dry well will never flood. Unfortunately, this can happen during storms or periods of intense rain.
- To make things easy, you can use a sequence of flags or spray paint to indicate the location of the drain pipe and dry well.
4
Call your local government before you dig to check for utility lines. Once you know where you want to install your well, call your local government to let them know you need a consultation for a dry well. Unless you live in a rural area, there are utility lines running all over the place beneath your yard. Your local government will want to check to see if there are pipes where you plan on digging.^{[4]
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- This service is almost always free. You may need to pay for a permit to build a well though.
- Depending on where you live, you may have a legal obligation to contact your local government to let them know you’re planning on installing a dry well.

Part 2

Part 2 of 4:

Digging Your Hole and Drain Lines

1
Dig a 4 by 4 ft (1.2 by 1.2 m) hole where you want the dry well. Use a long-handled shovel to start digging where you want your well to go. Start in the center by pointing the head of your shovel into the well. Use the heel of your shoe to punch the shovel into the ground. Lift the dislodged soil and toss it on to a tarp or in a wheelbarrow so that you can dispose of it or reuse it later to fill your ditch.^{[5]
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- Don’t do this if it has rained within the past 2 days.
- Try to dig the walls of your well straight down. This can be kind of tough though and it’s alright if the vertical sides angle down towards the center a little.
2
Dig a ditch running from your downspout to the well. Make your ditch roughly 12 in (30 cm) deep and 6 in (15 cm) wide. Use your shovel to dig in a straight line starting at the downspout. If there isn’t a decline running from your downspout to the well, dig slightly deeper as you work your way toward the well.^{[6]
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- A small ditch designed to redirect water is called a swale.
3
Ensure that your ditch declines ¹⁄₄ in (0.64 cm) for every 12 in (30 cm). Use a spirit level with hash marks for measuring angles and check the air bubble every 12 inches (30 cm) along your drain line. If you need to deepen your ditch, simply dig more soil out.^{[7]
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Tip: It’s okay if part of your ditch goes deeper than other sections. The depth of 12 inches (30 cm) is a minimum, not a maximum.

Part 3

Part 3 of 4:

Adding Your Piping

1
Connect a PVC downspout adaptor and elbow to your downspout. Measure the opening of your downspout and buy an adaptor that is the same size. Get an elbow joint to connect your adaptor to the ditch pipe. Slide the adaptor into the opening of your downspout and point the opening towards your ditch. Use a natural brush to add a layer of PVC glue to the inside of the connection for your elbow and adaptor. Slide the 2 pieces together hold it for 30-45 seconds to let the glue settle.^{[8]
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- PVC glue is toxic so you need to wear a dust mask and gloves when you’re working with it. You’re working outside though, so it shouldn’t be too tough to avoid the fumes.
2
Apply glue to 4 in (10 cm) PVC pipe and lay your drain line. Apply glue to the inside of each pipe fitting. Use your brush to add 1-2 layers of glue to the inside of each outer-fitting. Slide each piece of PVC together and work from the downspout towards your ditch. Let each pipe sit for 30-45 minutes to give the PVC glue time to dry.^{[9]
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- Measure the distance from the bottom of your spout to the middle of your well to determine how much PVC piping you need to buy. Add 5–6 feet (1.5–1.8 m) to your pipe measurement so that you have some backup pieces in case you need some extra pieces.^{[10]
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- If you bought a flat length of pipe, add glue to the inside of each fitting ring before sliding each pipe together.
3
Lay non-woven landscape fabric under your pipe as you work. While not mandatory, you can prevent leaks in your pipe from destroying or eroding the soil under your drain by laying unwoven landscape fabric underneath the pipe. Simply slice a length of fabric with a utility knife and slide it underneath your pipe as you’re laying it.^{[11]
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- Use your PVC piping measurement to determine how much you need for your ditch. You’ll need plenty of excess fabric to stick out of each side of your well, so add 20–35 feet (6.1–10.7 m) to your order.
- The landscape fabric will diffuse water and divert it over a larger surface area to protect the soil underneath it.
- Landscape fabric is sometimes called geotextile.
Tip: Your fabric lengths don’t need to be precise. As long as the fabric rests under the pipe you should be fine.
4
Spread 2–3 inches (5.1–7.6 cm) of gravel over the bottom of your well. Once you reach the well with your piping, fill the bottom of your well with loose gravel. Add a few inches of gravel and spread it out by hand so that it is even and covers the entirety of your well floor.^{[12]
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Part 4

Part 4 of 4:

Finishing Your Well

1
Buy a drain tank or make your own from a large bucket. Buy a drain tank if you want a clean connection between your pipes and the tank. Build your own if you want to save a little money. To build your own tank, get a large, plastic bucket. Drill 25-30 2 in (5.1 cm) drainage holes all over the bottom half of the bucket.^{[13]
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- Tanks aren’t particularly expensive to buy.
- If you use a bucket for your tank, it won’t be able to fit a pipe perfectly to the tank. This is fine though; the water will drip from the opening down to your bucket.
- A 40 US gal (150 L) drain tank will be perfect for a 4 by 4 feet (1.2 by 1.2 m) hole. There are bigger or smaller sizes though if you prefer.
2
Lay a sheet of landscape fabric in the well and add your tank. Line the entire interior of your well with landscape fabric. Spread the sheets out and push them into the sides and floor of your well. Lower your drain tank into the center of your hole so that the opening at the top lines up with the drain pipe. This will ensure that you can connect your last piece of piping.^{[14]
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- You do not need to affix the fabric to anything. The weight from the tank and the gravel will keep it in place.
3
Connect your drain pipe to the tank. You have a few options when it comes to how you connect the pipe to the tank. You can use a PVC elbow and an adapting piece to glue pipes together and slide it into the top of the drain tank. If you want a looser connection, use PVC glue to add a flexible pipe to the last length of your pipe. Fit it over the hole to your drain tank and wrap a worm drive around the connection before pulling the adjustable tab to tighten it. If you don’t want to connect the pipe, you can run the PVC pipe right over the opening for you tank.^{[15]
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- If you’re using a bucket as an improvised drain tank you won’t have anything to connect your pipe to. Simply leave the PVC opening directly over your bucket.
- You have to use a flexible pipe if your PVC pipe isn’t perfectly aligned with the opening of your drain pipe.
4
Fill in the remaining space in your well with loose gravel. Take your loose gravel and pour it all around your drain tank. Fill in the space over your tank once the sides are filled. Continue adding gravel until the pile of rocks is flush with the bed of your soil. Smooth the pile out on top so that it’s flat on your garden.^{[16]
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- Some people decorate the space around their gravel pit with flowers or decorative rocks. You can also add soil on top of the gravel, but this will make it hard to access your drain tank in the future.
- The gravel will ensure that the water drains evenly through the bottom of your well.
5
Cover your ditch with soil or gravel. You can either use soil or gravel to fill in the ditch that runs from your downspout to the tank. Either use a shovel to add the soil that you dug out from your ditch or pour rocks over each section of pipe.^{[17]
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- Try to avoid walking directly on your gravel or soil when you’re walking around your garden.

Community Q&A

Question

Referencing an earlier question: If I fill the barrel with gravel, why do I need the barrel at all? Couldn't I just terminate the drain into a gravel pit?

Community Answer

Yes, that method will work as well, however the larger stones inside the barrel allow it to keep its shape while being burred, and create larger pockets for water to fill. This increases the volume of water that the well can support over a traditional gravel filled well. You can buy a dry well that does not need to be filled. These effectively double the volume of the dry well, but they are engineered to a greater degree than the plastic barrel pictured here. I'm a bit old school and I can't justify burying a $65 trash can in my yard, so I like to use gravel filled wells myself.
Question

What size gravel should be used for the dry well?

Community Answer

#57 stone is the size to use.
Question

Why put landscape fabric in the tank?

Community Answer

To keep topsoil and debris from slowly backfilling the open space in the container. Water will go through the landscape fabric and out of the tank.