Splash blocks
A splash block is the humblest fix on the house. It only works when it points the right way and the ground beneath it slopes.
A splash block is a small trough, usually concrete or plastic, that sits under a downspout and spreads the water out and away from the wall. It is better than letting water hit bare soil. It is rarely enough on its own.
This page prints no prices. It explains what the block does and where it stops being useful.
What a splash block does
A downspout drops a lot of water in a narrow stream. On bare soil, that stream digs a hole and soaks the ground beside the footing. The block catches the fall, slows it and carries it a short way along its channel.
That is all it does. It does not carry water across the yard. It moves it a couple of feet, and the ground does the rest.
Where a splash block falls short
The block only helps if the ground it empties onto slopes away from the house. On flat or backward-sloping soil, the water simply pools a few feet from the wall and soaks back toward it.
- Blocks that have shifted or tilted toward the house send water the wrong way.
- Blocks sunk into the soil catch debris and hold water.
- In heavy rain, a short channel cannot keep up with a full downspout.
Be honest about the last point. In a downpour, a splash block is a speed bump, not a solution.
Make it work better
Set the block so the channel runs away from the foundation, and tilt it slightly downhill. Bed it on firm soil so it does not rock. Clear leaves out of it each season.
Check the ground beyond the block as well. If it is flat or dips toward the house, regrade it. The grading and downspouts page covers the slope that makes a splash block worth having.
When to choose a longer extension
If the downspout sits next to a basement wall that has leaked, a longer extension or a buried line does more. The downspout drain pipe page explains how to carry the water well clear. Take a position: if you already have wet-basement history, do not rely on a splash block alone.
An overflowing gutter can send water over the edge before it ever reaches the downspout. If that is happening, read gutter overflow before changing anything at the ground.
Where to stop and call someone
If water still reaches the basement after you fix the downspout and the slope, the cause may be deeper. Do not dig beside a wall that is cracked or bowed. That is a question for a licensed structural engineer. An independent one has no repair to sell you. Discharge rules are local, so ask your building department where you may send roof water.
Frequently asked questions
What is a splash block?
A small trough, usually concrete or plastic, placed under a downspout to spread the water and carry it a short way from the wall.
Is a splash block enough to protect my foundation?
Often not. It moves water only a short distance, so it works best on soil that slopes away from the house and for homes with no history of wet basements.
Which way should a splash block face?
Away from the house, tilted slightly downhill, on firm soil so it does not shift or rock.
When should I use a downspout extension instead?
When the downspout is near a wall that has leaked, or the ground is flat. A longer extension or a buried line carries water much farther.
Where is roof water allowed to drain?
Rules are local. Ask your building department before routing water to the street, to a neighboring lot or into a storm drain.
Sources
What this page explains is based on these official sources. If you check one and it does not match what you read here, send it to us and the article gets corrected.
- US EPA. What You Can Do to Soak Up the Rain
- US EPA. Soak Up the Rain. Managing stormwater around a property