Drain Rock in Washington
Also known as: 7/8 clean, washed rock
Drain Rock gives Washington drainage work a clean, open stone layer when rain sits over hardpan near a home or shop.
- Size: 3/4 inch to 1-1/2 inch
- Grading: Washed to remove fines and dust
- Type: Rounded or angular varieties
From $396 for 1 ton, delivery included (larger loads cost significantly less per ton)
Free delivery included
Free delivery anywhere in Washington
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Weekday delivery, earliest Nov 3
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Everything You Need to Know About Drain Rock
Size and Grading
- Size
- 3/4 inch to 1-1/2 inch
- Grading
- Washed to remove fines and dust
- Type
- Rounded or angular varieties
Water resting on hardpan can turn a small drainage job into a wet excavation, particularly west of the Cascades. Drain Rock is prepared as washed aggregate, without the dust and fine particles that would occupy its gaps. Those gaps let water circulate through the fill instead of stopping at the collection point.
Choose rounded material when the stone will be seen in a landscape detail; choose angular material where the fill will carry overlying soil. For a French drain through hardpan, line the trench with landscape fabric before placing the rock, then keep native soil from mixing into it. That separation preserves the open channels through seasons of rain.
Quickly Calculate How Much You Need
Material: Drain Rock
How to Measure
Measure the length and width of your project area in feet
Decide on depth in inches (2" for landscaping, 4" for driveways)
Enter the values above and we'll calculate the tonnage you need
Need help figuring out the right amount? We can help!
Call or text us at (206) 582-6792 and we'll help you calculate the right quantity for your project.
Not sure how much you need? The River Rock Calculator has depth guides, coverage charts and worked examples for this material.
Common Uses
French Drain Systems
French drains use drain rock to create an open route for water. On Puget Sound sites where water can sit above hardpan, it moves runoff away from footings, basements, and low ground, helping limit water damage.
Septic & Leach Field Construction
Use drain rock as the infiltrating layer in septic leach fields and drain fields. Clean, consistently sized aggregate supports wastewater systems built to health department specifications.
Retaining Wall Backfill
Water needs a route out from behind a retaining wall. Drain rock creates that route, reducing hydrostatic pressure that can damage or overturn the wall.
Foundation Water Control
Place drain rock along a foundation's perimeter to carry groundwater clear of basement walls and footings. This drainage helps stop moisture intrusion and hydrostatic pressure that can crack and damage the structure.
Why Choose Drain Rock
Open Water Flow
Washed drain rock contains little dust or fine material, leaving open spaces for water movement. Those voids allow drainage systems to move water freely.
Lasting Drainage
Crushed drain rock has angular pieces that hold open spaces under load. That helps resist the settling and compaction associated with rounded aggregate in a drainage trench.
Clean & Specification-Grade
Choose washed, graded drain rock for drainage applications. It pairs with drainage fabric, perforated pipe, and the other components of a drainage system.
Structural Protection
Drain rock directs water away from structures, retaining walls, and foundations. This can reduce moisture damage and hydrostatic pressure linked to costly structural repairs.
