How Much Gravel for a 30 Foot French Drain?
How much gravel for a 30 foot French drain: about 1.57 cubic yards, or roughly 2.2 tons, for a trench 12 inches wide and 18 inches deep with a 4-inch perforated pipe.
Volume and tonnage calculator →Gravel by trench size over 30 feet
| Trench (W × D) | Cubic yards | Tons |
|---|---|---|
| 6 × 12 in | 0.46 | 0.6 |
| 12 × 18 in | 1.57 | 2.2 |
| 12 × 24 in | 2.13 | 3.0 |
| 18 × 24 in | 3.24 | 4.5 |
Figures subtract a 4-inch pipe and assume about 1.4 tons per yard of washed stone.
Related: How Much Gravel for a 100 Foot French Drain?
Best stone for the drain
Use clean, washed stone with no fines, such as #57 or similar 3/4 to 1 inch stone. Fines clog the drain. Pea gravel also drains but shifts more. See the best gravel for a French drain.
Wrap and slope
Give the drain a steady fall of about 1 inch per 8 to 10 feet, around 3.3 inches over 30 feet, and make sure it outlets somewhere the water can go. Wrap the stone in filter fabric so soil does not migrate in. Call 811 before digging.
Related: How Much Gravel for a 10 Foot French Drain?
Common mistakes
Using gravel with fines, skipping the fabric and laying the pipe with no consistent slope are the usual causes of failure. A drain with no proper outlet simply fills and holds water. Another mistake is digging without calling 811 to locate buried lines.
Measuring the run
Walk the route the water should take and measure it in feet, including turns. Mark the outlet first: the drain has to send water somewhere lower, such as a dry well, a ditch or daylight at a slope. Measure the trench depth at both ends so the fall is consistent.
Cost and tools
Gravel is the bulk of the material cost, followed by pipe and fabric. Renting a trencher saves a lot of digging on long runs. A wheelbarrow, a flat shovel and a level finish the toolkit.
Questions people ask
How many tons of gravel for a 30 ft French drain?
About 2.2 tons for a 12x18 inch trench.
How many yards of gravel for a 30 ft French drain?
About 1.57 cubic yards.
What size gravel for a French drain?
Clean washed stone around 3/4 inch, such as #57.
How much slope does a French drain need?
About 1 inch of fall per 8 to 10 feet.
Do I need fabric for a French drain?
Yes, non-woven filter fabric keeps soil out of the stone.
Related guides
- Best Gravel for a French Drain: Size and Type
- French Drain Along an Asphalt Driveway
- How Much Gravel for a 20 Foot French Drain?
- How Much Gravel for a 25 Foot French Drain?
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