What Is Drainage Rock?
Drainage rock, or drain rock, is washed and screened stone with the fines taken out. That single detail is what makes it work. With no silt or clay in the mix, the spaces between the pieces stay open, so water runs through the rock instead of sitting on it. Put the same rock in a trench around a perforated pipe and you have a path that pulls water out of saturated ground and carries it somewhere else.
It is the exact opposite of base rock. Base is deliberately blended with fines so it compacts into a hard, water-shedding surface, which is what you want under a driveway and the last thing you want inside a drain. If you are stabilizing a road instead of draining a yard, start with our road base and Class 2 base page instead.
At our Fresno yard, drainage jobs get filled from a handful of materials: 3/8" pea gravel for tight trenches, 3/4" crush river rock for general drain work, and larger river rock and Noiyo cobble for swales, channels, and erosion control. All of it is sold by the ton, and you are welcome to come look at the piles side by side before you order. Browse the wider landscape materials lineup for decorative options that pair with a drainage project.
Drainage Rock & Gravel We Stock
Sized from small trench gravel up to cobble for channels and erosion control.
3/8" Pea Gravel
Small rounded stone that flows easily into narrow trenches and around perforated pipe. The usual pick for French drains and behind retaining wall drainage.
3/4" Crush River Rock
Washed, screened rock in the 3/4" range with the fines crushed out. Open voids let water move through fast, making it a workhorse for drain rock and dry wells.
1"-1.5" River Rock
Larger rounded river rock for dry creek beds, downspout splash areas, and swales that need to carry real water without shifting.
1 x 4 River Rock
A mixed-size river rock that reads natural in a dry creek bed and stays put on gentle slopes where smaller stone would wash.
2"-4" Noiyo River Cobble
Cobble sized for swale bottoms, culvert outlets, and channel edges where flowing water would move lighter rock downstream.
Where Drainage Rock Gets Used
Six jobs cover nearly every drainage load we sell in Fresno and Clovis.
French Drains
A trench, perforated pipe, filter fabric, and washed rock around it. Water finds the voids in the rock, drops into the pipe, and leaves. Pea gravel or 3/4" crush river rock both work; the key is that the rock is washed so fines do not clog it.
Yard & Lawn Drainage
Low spots that hold water for days after a storm are a grading and drainage problem, not a lawn problem. A rock-filled trench or a shallow gravel swale gives the water a path to a lower point, a street, or a basin.
Downspout & Splash Areas
Roof water dumped against a foundation is one of the most common causes of settling and wet crawlspaces here. A rock splash pad and a rocked channel move that water out and away.
Dry Creek Beds
The most attractive way to handle runoff in a Fresno yard: a shaped channel lined with mixed river rock and cobble that looks intentional when dry and carries water when it rains.
Retaining Wall Backfill
Walls fail from water pressure behind them far more often than from the load in front. Free-draining rock behind the wall with a drain line at the base relieves that pressure.
Planter & Pot Drainage
Raised beds, planters, and large pots drain better with a rock layer at the bottom, and gravel around the base of a structure keeps splash and mud off the finish.
Building a French Drain in Central Valley Clay
Fresno soil is the reason so many yards here pond after a storm. Clay absorbs water slowly, so once the surface saturates the rest has nowhere to go. A French drain does not make clay drain faster, it gives the water a fast lane out. Get these six things right and the drain works for decades.
Bring your trench dimensions to the yard or call and we will tell you how many tons to order. For larger jobs we deliver by the truckload through our material delivery service, and you can move a few yards yourself with a rental dump trailer.
Erosion Control, Swales & Rip Rap Style Armoring
Once water is moving, the job changes from drainage to erosion control. Flowing water picks up soil and small stone, so the rock at the bottom of a swale, at a culvert outlet, or along a bank has to be heavy enough to stay where you put it. The rule of thumb is simple: the faster and deeper the flow, the bigger the stone.
For residential swales and dry creek beds, 1" to 4" river rock usually holds. At outlets, on steeper channels, and along ditch banks, step up to 2"-4" or 4"-8" Noiyo river cobble, which is the largest stone we carry and what we supply for rip rap style armoring on residential and light commercial work. Set the stone on filter fabric, key the upstream edge in below grade so water cannot get under the apron, and extend the armoring past where the fast water dissipates.
We do not stock a graded engineered rip rap under that name. If your plans specify a gradation or a Caltrans class, call (559) 233-6603 with the spec and we will tell you straight whether what we carry meets it.
How Much Drainage Rock Do You Need?
For a trench, multiply width by depth by length in feet, then divide by 27 for cubic yards. A 12-inch wide, 18-inch deep, 50-foot trench comes out around 2.8 cubic yards before you subtract the pipe. For a dry creek bed or swale, treat it as a surface at the depth of rock you want, generally 3 to 4 inches for river rock and more where cobble is set as a single layer.
Order slightly over the calculation. Rock settles into the trench walls, and running short in the middle of a dig means a second delivery fee.
Drainage Rock Delivery Area
Bulk delivery from our Fresno yard across the Central Valley, plus pickup and self-haul.
Fresno, CA
Drain rock, pea gravel, and river rock by the ton from our South Elm Avenue yard, with pickup, self-haul, and delivery.
Clovis, CA
Delivery for French drains, dry creek beds, and yard drainage projects across Clovis and the northeast side.
Madera, CA
Bulk drainage rock and cobble delivered for rural properties, culvert outlets, and ditch work.
Sanger, CA
Quick access from Highway 180 for drain rock loads and erosion control stone.
Selma, CA
Washed rock and cobble delivered for drainage, swales, and bank protection on farms and homesites.
Why Choose American Rock and Rent
Drainage Rock FAQs — Fresno, CA
Have questions? We've got answers. If you don't see your question below, give us a call at (559) 233-6603.