Downspout Drainage Options: Extensions, Buried Lines, French Drains and Rain Barrels

The goal

The point of every option is the same: get roof water far enough from the house that it does not soak the soil against the foundation, and send it somewhere it can soak in or flow away without causing new problems. The residential code adopted locally (Wichita-Sedgwick County Unified Building and Trade Code (2018 IRC adoption and permit exemptions)) uses 5 feet from foundation walls as the minimum where expansive or collapsible soils are known to exist (ICC, 2018 International Residential Code, Section R801.3 roof drainage).

Option 1: Splash blocks

A concrete or plastic pad under the downspout elbow. Pros: inexpensive, simple. Cons: water still lands within a couple of feet of the wall. Best on sites with excellent grading, or combined with an extension.

Option 2: Downspout extensions

Extra lengths of downspout, fixed or hinged, carrying water out several feet. Pros: inexpensive, effective, easy to inspect. Cons: in the way of mowing and foot traffic; hinged extensions that flip up help. Flexible roll-out sleeves are cheaper but less durable.

Option 3: Buried solid pipe

The downspout connects to smooth-walled solid pipe buried underground, sloped to a daylight outlet downhill or to a pop-up emitter in the lawn. Pros: out of sight, out of the way, carries water far. Cons: needs enough fall across the yard, can clog with leaves and silt, and roots or vehicles can crush it. Use solid pipe rather than perforated pipe for downspout lines so water is carried away rather than released along the way, include a cleanout, and protect the outlet.

Option 4: French drains

A trench with perforated pipe in gravel, usually wrapped in filter fabric, that collects water from the soil and carries it downhill. Pros: handles soggy areas and groundwater along a wall or across a yard. Cons: not designed to take the full flow of a downspout; mixing the two can overload the drain. Often installed alongside a separate solid downspout line.

Option 5: Dry wells

An underground pit or chamber filled with gravel or a plastic tank that stores water and lets it soak into the ground. Pros: useful where there is no downhill outlet. Cons: clay soils drain slowly, so a dry well can fill and back up during long rains. It must be well away from the foundation.

Option 6: Rain gardens and swales

A planted shallow depression or channel that receives downspout water and lets it soak in. Pros: attractive, reduces runoff. Cons: needs space and should be well away from foundations and neighbors. The EPA's Soak Up the Rain program promotes redirecting downspouts to lawns, gardens and rain gardens where site conditions allow (EPA Soak Up the Rain, disconnect and redirect downspouts).

Option 7: Rain barrels

A barrel under the downspout collects water for garden use. Pros: free water for plants. Cons: a single barrel fills in minutes during a storm, so the overflow still needs a path away from the house. Barrels must be covered to keep mosquitoes out; the CDC lists rain barrels and gutters among places mosquitoes lay eggs (CDC, larvicides and where mosquitoes lay eggs). Drain them before freezing weather, which in Wichita averages from late October to early April (Wikipedia: Wichita, Kansas (climate)).

Comparison

Choosing for your yard

• Yard slopes away and you do not mind seeing it: extensions.
• Extensions are in the way: buried solid pipe to a downhill outlet or emitter.
• Soggy area or water along a wall even when it is not raining: a French drain, plus a separate downspout line.
• Flat lot with no outlet: long extensions to the lowest practical point, a rain garden, or a dry well sized for slow clay drainage.
• Gardener: rain barrel with a planned overflow.

Rules and neighbors

Do not direct water onto a neighbor's property, a public sidewalk or into a sanitary sewer. Many cities have rules about where roof drainage and outlets can go, especially near curbs and property lines, so check with your city before burying a line that daylights near the street. See downspouts and drainage for the downspout side of the system.

Maintenance that keeps drainage working

Check extensions after mowing and storms, flush buried lines once or twice a year with a hose from the downspout end, keep pop-up emitters clear of grass and mulch, and clean outlet strainers. A drainage system that is not maintained slowly stops doing its job, usually unnoticed until the next big rain.

Related services

• Downspouts & Drainage: Add, upsize or relocate downspouts and carry water away from the foundation.
• Gutter Installation: New seamless gutters and downspouts measured, sized and pitched for your roof.
• Gutter Repair: Fix leaking seams and corners, sagging or loose runs, bad pitch and damaged downspouts.

Sources: ICC, 2018 International Residential Code, Section R801.3 roof drainage; Wichita-Sedgwick County Unified Building and Trade Code (2018 IRC adoption and permit exemptions); EPA Soak Up the Rain, disconnect and redirect downspouts; CDC, larvicides and where mosquitoes lay eggs; Wikipedia: Wichita, Kansas (climate).