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How toDownspouts & Drainage

How do I extend a downspout away from my foundation?

Fit an elbow at the bottom of the downspout and attach a solid extension pipe that carries the water at least 5 feet from the house, ideally 10, onto ground that slopes away. End it on a splash block or stones. A buried line works too, but in Virginia you submit a locate request to Virginia 811 before you dig.

Free to ask. Local shops send quotes, and you pay only when you book one.

By Kasra Taheri, Founder, LoclisPublished

Researched and drafted with AI, then checked claim by claim against the sources listed below before it was published. Prices and rules change; the dates beside each source say when it was last checked.

Step by step

Read when to stop and call a pro, further down this page, before you start.

  1. Step 1: Watch it in the rain

    During a steady rain, note where each downspout drops its water and which way that water runs, toward the house or away from it.

  2. Step 2: Pick where the water will go

    Choose a spot at least 5 feet out, 10 if you have room, on ground that slopes away and is not your property line.[1][3]

  3. Step 3: Fit an elbow at the bottom

    Attach a front or side elbow to the downspout's bottom so the outlet points away from the wall, and secure it with sheet metal screws.[5]

  4. Step 4: Attach the extension

    Slide a solid extension or non-perforated corrugated pipe over the elbow and fasten it so it cannot be knocked off.

  5. Step 5: Keep it running downhill

    Check with a level that the pipe falls away from the house along its whole length, with no low spot where water can sit.

  6. Step 6: Protect the outlet

    Set a concrete or plastic splash block at the end, and add fist-sized stones beyond it if the soil still washes.[2]

  7. Step 7: Request a locate before burying

    If the line will go underground, submit a Virginia 811 locate request at least 3 working days before you dig and wait for the positive response.[9]

  8. Step 8: Dig a sloped trench

    Hand dig a shallow trench that falls at least 0.5 inch per foot away from the house, and keep to hand tools near any utility marks.[1][9]

  9. Step 9: Lay solid pipe

    Connect and seal non-perforated pipe directly to the downspout, and never tie it into a perforated foundation drain.[1]

  10. Step 10: Finish the outlet

    End a buried line at a pop-up emitter set at the lowest point of the run, away from buildings and the curb.[6]

  11. Step 11: Test before you backfill

    Run a hose into the downspout and confirm water comes out the far end freely before you fill the trench and reseed.

Fit an elbow to the bottom of the downspout, attach a solid extension pipe, and run it downhill to a spot well away from the house where the water can soak in or flow off without coming back. An above-ground extension is an hour or so of work with inexpensive parts. A buried line looks tidier and stays out of the mower's way, but it is a digging job, and in Virginia digging starts with a call to 811.

Rainwater pouring from the bottom of a cast-iron downspout onto a concrete splash strip at the base of a brick wall
Photo: oatsy40 from London, CC BY 2.0, via Wikimedia Commons

How far the water needs to go

The Building America Solution Center, run for the U.S. Department of Energy, says downspouts should end at least 5 feet from the foundation, or drain to an underground catchment system at least 10 feet from it.[1] Virginia Cooperative Extension's homeowner fact sheet goes further for surface extensions and says to "direct the runoff 10 feet away from the foundation and into the landscape."[4] It is worth the extra length: Fairfax County's Northern Virginia Soil and Water Conservation District notes that when it rains hard, "an average sized home can experience hundreds of gallons of runoff coming from the roof."[2]

Distance only helps if the ground keeps the water moving away. The district recommends land that slopes away from the foundation walls, ideally a 5% grade for a distance of ten feet around the home,[2] which its glossary translates as at least a six-inch drop over the first ten feet.[3] If the spot by the downspout has sunk into a dip, fill it before you add an extension, or the pipe will just empty into a puddle.

Where the water lands matters as much as how far it travels. The glossary says a steep slope, compacted soil or the strip right next to a foundation wall are poor outlets, and that your property line is not a suitable outlet either.[3] Good ones are a lawn or planting bed that drains well, a swale, a rain garden or a dry well.

Choosing an above-ground extension

Most extensions start at an elbow. Amerimax's gutter instructions have you attach a front or side elbow at the bottom of the downspout to turn the water away from the foundation, and they list a Downspout Extension, Splashblock, Dripper Flipper, or Flex-A-Spout as ways to carry it farther.[5] The Fairfax district suggests extensions made of non-perforated corrugated plastic pipes that can be laid on the ground or buried.[2]

Virginia Cooperative Extension adds two practical choices. First, an extension pipe can have holes in it so water seeps out along its length, or be solid so it all leaves at the end.[4] Next to the house, solid is the safer pick. Second, across a lawn, consider a hinged or flexible extension that can be moved out of the way when mowing.[4] The same fact sheet, updated in June 2024, put the cost of this kind of rooftop redirection at $25 to $100 per downspout, depending on the fittings and pipe length.[4]

Keep the outlet from washing out

Concentrated roof water digs a hole where it lands. The Fairfax district suggests a concrete or plastic splash block at the end of the pipe, and fist-sized or smaller stones along the flow path if erosion continues.[2] Virginia Cooperative Extension suggests a spreader kit that breaks the flow into many small streams, or a splitter that sends it two ways, and says the pipe should release onto reasonably flat ground rather than a steep slope.[4] A thick lawn or a planted bed at the outlet also slows the water and uses much of it.

Burying the line

A buried extension follows the same rules underground. For a downspout drain, the Building America guide says to use non-perforated, smooth or corrugated plastic pipe, to connect and seal it directly to the downspout, and to bury it at a slope of at least 0.5 inch per foot away from the home for at least 10 feet.[1] It also warns: do not connect it to a perforated foundation drain, which will soak the foundation.[1]

The far end needs somewhere to let the water out. A common choice is a pop-up emitter, a capped fitting whose cap pops up as water pressure builds and closes once the flow drops.[6] Its maker, NDS, says to install the emitter at the lowest point in the drainage system, away from buildings and away from the curb.[6] If the yard has no lower spot within reach, the line can end in a dry well or rain garden instead.

Before the first shovel goes in, request a utility locate. Virginia Code § 56-265.17 says: "No person shall make or begin any excavation or demolition without first submitting a locate request to the notification center".[7] The statute defines excavation as any operation in which earth is moved or displaced "by means of any tools, equipment, or explosives", and it names trenching and digging.[8] Virginia 811's homeowner FAQ says you must contact Virginia 811 at least 3 working days before you dig, for projects as small as a mailbox or landscaping.[9] The service costs the homeowner nothing.[11] Once the marks are down, state law sets a two-foot tolerance zone on either side of the marks, where only certain kinds of digging, such as hand tools, are allowed.[9]

The locate covers public utilities only. Virginia 811 lists private lines it will not mark, including lines running to a detached garage or shed, invisible pet fences, and septic and propane lines.[10] If you have any of those, find them before you trench.

Stop and call a pro if

  • The utility marks run across the path you need and you cannot route around them.
  • You hit rock, roots you cannot cut by hand, or a pipe or cable that was not marked. Stop digging and report a damaged line.
  • The run has to cross a driveway, walkway or patio, or there is no lower spot within reach to drain to.
  • Water is already getting into the basement or the foundation is cracking. The Fairfax district warns that "Wet basements and wall or foundation cracking can have serious consequences" and should be dealt with right away.[12]
  • Water still pools against the house after every downspout is extended. That points to grading, which is a bigger job; see why water pools near a foundation.

For a buried line done by someone else, see how much it costs to bury downspouts in Virginia and who installs underground downspout drains. You can also browse downspout and drainage businesses, exterior pros around Blacksburg and the other exterior answers. When you would rather hand it off, describe the downspout job once and licensed local businesses quote it.

Common questions

How far should a downspout extension reach?
At least 5 feet from the foundation, and 10 feet where the yard allows. The Building America Solution Center, run for the U.S. Department of Energy, uses 5 feet for a surface outlet and 10 feet for an underground catchment such as a dry well. Virginia Cooperative Extension shows extensions carrying water 10 feet out into the landscape.
Should a downspout extension be perforated or solid?
For carrying water away from the house, solid. The Building America guide calls for non-perforated pipe on a buried downspout drain, and Fairfax County's soil and water district suggests non-perforated corrugated pipe for extensions. A perforated pipe lets water out along the way, which is useful out in a lawn bed but not right beside the foundation.
Do I need to call 811 to bury a downspout extension?
Yes. Virginia's Underground Utility Damage Prevention Act says no person may begin an excavation without first submitting a locate request, and its definition of excavation covers digging with any tools. Virginia 811 asks homeowners to contact it at least 3 working days before digging. The service is free, but it does not mark private lines such as a feed to a shed.
Can I run my downspout onto the driveway or toward the neighbor?
Fairfax County's soil and water district describes a property line as an unsuitable outlet and warns against solving your own problem by creating one for a neighbor. Virginia Cooperative Extension suggests sending roof water onto lawn, beds or a rain garden, where it can soak in, rather than onto paving that carries it to the street.
The extension is in the way of the mower. What can I use instead?
Virginia Cooperative Extension suggests a hinged or flexible extension that flips up or moves aside for mowing. Amerimax lists a Dripper Flipper and a Flex-A-Spout alongside plain extensions and splash blocks. A buried line with a pop-up emitter at the far end removes the pipe from the lawn altogether.

Sources

  1. [1] Gutters and Downspouts, Building America Solution Center, Pacific Northwest National Laboratory, U.S. Department of Energy. Checked October 26, 2026.
  2. [2] Gutters and Downspouts: Wetness or Erosion Problems, Northern Virginia Soil and Water Conservation District, Fairfax County. Checked October 26, 2026.
  3. [3] Glossary, Solving Drainage and Erosion Problems, Northern Virginia Soil and Water Conservation District, Fairfax County. Checked October 26, 2026.
  4. [4] Stormwater Management for Homeowners Fact Sheet 1: Rooftop Redirection (Disconnection), Virginia Cooperative Extension. Checked October 26, 2026.
  5. [5] Installing Metal Gutter Systems, Amerimax Home Products. Checked October 26, 2026.
  6. [6] Pop-Up Drain Emitters, NDS. Checked October 26, 2026.
  7. [7] Va. Code § 56-265.17, Notification required prior to excavation or demolition, Code of Virginia, Virginia General Assembly. Checked October 26, 2026.
  8. [8] Va. Code § 56-265.15, Definitions (Underground Utility Damage Prevention Act), Code of Virginia, Virginia General Assembly. Checked October 26, 2026.
  9. [9] Homeowners FAQ, Virginia 811. Checked October 26, 2026.
  10. [10] Private Utilities Explained, Virginia 811. Checked October 26, 2026.
  11. [11] The Process, Virginia 811. Checked October 26, 2026.
  12. [12] Solving Drainage and Erosion Problems: A Guide for Homeowners, Northern Virginia Soil and Water Conservation District, Fairfax County. Checked October 26, 2026.

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