Drain Rocks: All What You Need To Know

Water drainage is an important aspect of any landscaping project. Because if not handled properly, stormwater can ruin outdoor space, create swampy areas, and even cause foundation damage in some cases.

Therefore, having proper drainage is an absolute necessity. Most drainage solutions filtrate water through a layer of gravel or drain rocks before the water reaches the local aquifer.

What are Drain Rocks?

Drain rock is a type of gravel that is used in drainage systems to filter water through the small gaps between the rocks.

When water flows through the gaps between the rocks, sediment and other particles in the water are trapped and filtered.

Rocks in Drainage Ditch

It is typically made up of crushed rock and gravel of varying sizes and is used in conjunction with sand to filter water before it reaches the aquifer.

Drain rocks are used most commonly in drainage areas, like ditches and swales. But they can also be used to fill low spots on driveways, pathways, and other areas where water may collect.

Drain rocks can be in different sizes and be placed in multiple layers to create a more efficient drainage system.

What are the uses for Drain Rocks?

Drain rocks are a versatile material that has many uses. By understanding how they work and what they can do, you can use them for many areas beyond just drainage.

They can be used to:

Fill in Low Spots on Driveways and Walkways

How many times have you driven or walked over a low spot in your driveway or on the sidewalk and felt a bump?

This is typically caused by a depression in the surface that collects rainwater, resulting in a swampy area. You can eliminate this problem and create a smooth, even surface by filling in these low spots with drain rocks.

Reshape Pavers

Drain rocks are also used to reshape pavers. Because of the weathering process, paver edges appear to sink and crack over time.

To repair or reshape these pavers, use a layer of drain rocks to help hold them in place and prevent further sinking or cracking.

Rain Gardens

Drain rock is a great material for helping with stormwater management of rain gardens.

Rain gardens are landscape features that are used to collect and filter stormwater runoff from roofs, driveways, and other hard surfaces.

By using a layer of drain rocks in the rain garden, you can help improve water filtration and reduce the number of pollutants that reach the local aquifer.

Soil Amendment

Drain rocks can also be used to improve the soil. A lot of times, these rocks will be mined from quarries and will include minerals that can help improve the soil.

When you mix these rocks into the soil, they will help to improve the overall quality of the soil and make it more fertile.

Soil Stabilization

Drain rock is also used as a soil stabilizer in many applications. When added to the topsoil, it helps to improve drainage and reduce erosion.

The rocks can also be used to stabilize roads, embankments, and other areas that are prone to erosion.

Maintain Soil Moisture

Drain rocks are often used in agriculture to help maintain the moisture of the soil.

By using drain rock as a layer on top of your existing soil, you can prevent sun drying the soil and reduce evaporation. This will help to keep the moisture in the soil at a consistent level and improve crop yields.

Protect the Building Foundation from Water Damage

Drain rocks are a great material to use around the home foundation. Stormwater if not addressed properly can propagate to your foundation and cause costly damage.

By placing drain rocks by your house’s perimeter you help prevent water from reaching these areas and causing damage.

Pipe bedding

Pipe bedding is used to help stabilize and protect pipes from sinking into the ground.

Drain rock is often used for pipe bedding because it helps steady, secure, and protect the pipe from being damaged. The rocks also help to keep the area around the pipe clear of any obstructions or debris.

Fill in mud holes

Mud holes are a common problem in areas where the ground is soft and impermeable.

They can be dangerous to walk or drive on and can also be a breeding ground for mosquitoes. Drain rock can be used to fill in these holes and create a firm surface that is safe.

Flower beds

Drain rock is also a great material to use in flower beds. By using a layer of drain rocks, you can help improve the drainage in these areas and prevent waterlogging.

The rocks will also help to keep the soil loose and friable, making it easier for plants to grow.

French drains

French drains are a type of drainage system that uses a sloping trench filled with gravel, rocks, or other materials to help move water away from an area.

Drain rock is often used in these systems at the bottom of the trench to help filter the water before moving it away.

Under Concrete

Drain rock can also be used as a base material for concrete. This can significantly reduce the amount of concrete needed for the job without sacrificing strength.

Also, using drain rock as a base can help keep the concrete from cracking due to changes in moisture levels.

Construction projects

Drain rock is also used in many construction projects. It can be used as a base material for roads, sidewalks, and other structures.

The rocks can also be used to help stabilize the ground for all construction vehicles using the area.

Driveways

Drain rock can also be used on top of driveways to increase traction and make it less likely to get slippery. This can be good practice for colder climates where ice and snow are common.

Which rock is the best as a drainage rock?

Drain rocks can be made from a variety of materials, but some are better suited for drainage than others.

The ideal drainage rock shouldn’t lose its integrity being in contact with the water and be close to rounded in shape so that it doesn’t create large gaps at the joints.

Type of RockCharacteristicsBest UseCost
Lime RockInexpensive, not resistant to water, creates large gaps at jointsStabilizing driveways and walkwaysLow
River RockRound, smooth, does not lose integrity when in contact with waterPipe bedding, drainage rock, landscapingLow
GraniteHighly resistant to water, creates firm surface without gapsPermanent, long-lasting drainage solutionsHigh
BasaltStructural integrity, less resistant to water than river rock, rich in nutrientsDrainage systems, soil improvementModerate-High
SlateResistant to water, expensive, typically used in high-end applicationsHigh-end drainage projectsHigh
Types of Drain Rocks

Let’s take a look at some of the commonly used rocks for drainage:

Lime Rock

Pile of Gray Lime Stones

Lime Rock is inexpensive but a poor choice to be used as drainage rock. It is not resistant to water and deteriorates over time when exposed to it.

It is also not very round and will create large gaps at the joints, which isn’t ideal for a drainage system.

However, lime rock is still a popular choice to stabilize driveways and walkways because of its low price and easy availability.

River Rock

River Rock is a good choice for drainage because it is round, smooth, and doesn’t lose its integrity when in contact with water.

River rocks

It is often used as pipe bedding and drainage rock in landscaping because it helps to create firm, stable areas that won’t get soft and sink over time.

These rocks will last a long time and are ideal for areas that need permanent aesthetic appeal.

Surprisingly, these rocks are also inexpensive and easy to find, making them an ideal choice for drainage.

Granite

When it comes to water filtering and retaining properties, granite rock is the best option for drainage.

It is highly resistant to water and will not deteriorate over time. It is also a very smooth rock, meaning that it will create a firm surface for walkways and driveways without creating large gaps at the joints.

Granite rocks

However, granite rock should be used sparingly in drainage systems because of its high price and scarcity.

It is best suited for areas that need a permanent, long-lasting solution to drainage problems.

Basalt

Basalt is a rock that is commonly used in drainage systems because it has the structural integrity to withstand being exposed to water. It won’t deteriorate like lime rock but is still less resistant to water than river rock.

Basalt comes from deeper underground than most other rocks and requires more resources to mine and process. It is also a heavier rock, so it can be difficult to move around once it’s in place.

Basalt pebbles

Basalt is very rich in nutrients which makes it a good choice for landscaping projects that are looking to improve the quality of soil in an area.

However, basalt is typically more expensive than other drainage rocks due to its rarity, mining process, and potential transportation costs.

Slate

Slate is a fine-grained, metamorphic rock that can be a good choice for drainage systems.

However, it is also resistant to water and will not degrade over time. Slate is an expensive option for drainage and is typically only used in high-end applications like kitchen countertops and floor tiles.

Black Slate Rock

However, if you can find a source for slate drainage rock, it will be a good long-term solution for your drainage needs.

Where are drain rocks sourced?

Drain rocks can be sourced from a variety of places including quarries, rivers, and lakes.

Depending on the type of rock, its formation process, and other uses, the price can vary significantly. Local quarries are typically a good choice for drainage rock because they can be purchased at a lower cost.

Can I use river rock for drainage?

You can perfectly use river rock for drainage provided the size of the rocks is appropriate for the job.

River rock is one of the best options for drainage because it is round, smooth, and doesn’t lose its integrity when in contact with water.

How to install drain rocks? 

Drain rocks are installed depending on the application that they are being used for.

If they are used in a French drain system, they will be placed in a trench at the bottom of the drain.

If they are being used to create a stable surface for walkways or driveways, they will be placed in a layer on top of the soil and compacted. The intended purpose of the drain rock will determine its installation method.

Conclusion

Drain rocks are an important part of any drainage system. They help to keep the area stable and prevent erosion while also providing a pleasing aesthetic.

There are a variety of different types of drain rocks that can be used depending on your needs and budget. Always consult with a professional before installing drain rocks to ensure that you are using the right type for the job.

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