What Is Drain Rock?

Drain rock is washed aggregate sized to move water freely without carrying fines with it.

What is drain rock?

Drain rock is a washed aggregate — usually 3/4" — that has been rinsed to remove the fine dust and sand that normally coats crushed rock.

That washing step matters: fines are what clog French drains. Any drainage aggregate that hasn't been washed will silt up its own drainage over the first few storms.

Common sizes

3/4" — the residential standard. Matches most 4" perforated pipe perforations.

1" and 1 1/2" — used on civil, commercial, and high-flow drainage systems.

When to use drain rock

French drains, dry wells, foundation drains, and behind retaining walls. Anywhere water has to move through the aggregate without carrying silt with it.

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Best Rock for French Drains

3/4" washed drain rock is the residential standard. Skip pea gravel, unwashed base, and river rock.

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How to Build a French Drain

The classic residential French drain — a step-by-step from trench to daylight.

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Drain Rock vs River Rock

Drain rock does the work. River rock covers it up. Most jobs use both.

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