Should you put gravel under a drainage pipe?

Author: Prof. Norbert Adams  |  Last update: Wednesday, November 26, 2025

All drainage pipes should be placed on the gravel bed in the trench. PVC drainpipe, if used, should be placed in the trench with the holes facing down. Pipe connections shall not impair the overall function of the pipeline.

Do you need gravel under a drain pipe?

Round gravel is used to fill the trench, and a pipe with holes has been added to allow water to readily flow away from the home. One of the most important parts of the French drain is the gravel because it enables water that has seeped through the ground to be taken away down the slope of the drain.

What do you put under a drain pipe?

A mesh sock is usually placed around perforated drain pipe to keep soil fines from falling into the drain pipe clogging it. Another approach is to line the trench sides and tops with fabric and then put drain rock in the trench between the pipe and the fabric.

Does adding gravel help with drainage?

Its coarse texture maintains gaps that allow rapid water flow. This prevents standing water and redirects runoff away from problem areas. There are several effective ways to leverage gravel's superior drainage properties: Gravel driveways and walkways shed water to the sides where it can infiltrate into the ground.

What should drainage pipe be laid on?

All pipes should be laid in a trench that is 300mm wider than the pipes themselves. In addition to this, all plastic pipe runs need to be laid on a 10mm layer of pea shingle or fine gravel. This will provide a base for larger grade material and backfill to be placed on top later.

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How deep should drainage pipe be buried?

Dig a trench from the place in your yard that needs drainage to your chosen outlet. Check for underground utility lines and pipes before digging. The trench should be about 18 inches deep and 9 to 12 inches wide.

Can you use grey drainage pipe underground?

Technically, a soil pipe (i.e. a black, white, or grey 110mm pipe) should only be installed above ground. Once the soil pipework goes below ground, it should be connected to a terracotta foul water drainage pipe.

What is the best gravel for drainage pipes?

Pea Gravel: Small, smooth, and round, pea gravel is both aesthetically pleasing and effective in allowing water to pass through quickly. River Rock: Larger and more decorative, river rock can be the best choice for a significant drainage project.

Can gravel be used as a drainage layer?

By creating a drainage layer using gravel or stone, you promote the healthy movement of water through the soil, helping to prevent waterlogging and root damage in your plants.

How deep should gravel be for drainage?

The answer is anywhere from 12-18 inches. This is to give stormwater the proper amount of space to drain through your aggregate and into the soil below without flooding. The ideal depth of your gravel driveway will depend on how much rain your area typically gets.

What do you put under gravel for drainage?

Silt Film Woven Geotextiles

This product is also known as silt fence and serves as a vertical barrier held in place with wooden or metal stakes to help prevents sediment from flowing downhill. This type of fabric is also used under gravel paths and for some road construction applications.

Why do you put pea gravel around pipes?

Then use more pea shingle for the back fill and side fill so that the pipe is surrounded in the trench. This helps to protect and support the pipework and allow for expansion and natural ground movement.

What is under drain pipe?

Underdrains prevent water from accumulating under the pavement and causing premature subgrade failure. Open-graded material placed directly above the underdrain helps move water out from between asphalt layers.

When not to use pea gravel?

Mobility: Due to its round and smooth shape, pea gravel can easily shift underfoot, which can lead to instability in walkways or patios. This mobility can also make it challenging for outdoor furniture to stay stable. Weed Growth: While pea gravel can deter some weed growth, it's not a foolproof solution.

How do you lay gravel for drainage?

Here's what you need to do:
  1. Clear the area: Remove any grass, weeds, or debris from the area where you'll be laying the gravel. ...
  2. Level the soil: Use a rake to level out the soil and create a smooth, even surface. ...
  3. Compact the soil: Use a tamper to compact the soil, creating a firm foundation for your gravel.

Can a drain pipe go straight into the ground?

UK building codes require downpipes to exit a metre from foundations to avoid saturated soil that could undermine structures. Surface drains and soakaways are best as they slowly absorb water, unlike sewers which risk flooding if pipes discharge directly into them as this can overwhelm the drain system.

Does gravel affect drainage?

Gravel is a key component in many drainage systems. Its porous nature allows water to flow through it easily, making it ideal for use in French drains, dry wells, and as a top layer on graded slopes. The size and type of gravel used can significantly affect the efficiency of the drainage system.

What material is used for below ground drainage pipes?

These include terracotta PVC sewer pipe, twinwall drainage pipe, MDPE water pipe and land drainage pipe. Land drainage coil sizes range from 60-160mm and twinwall comes in sizes from 100-900mm.

Is pea gravel the same as crushed stone?

As mentioned earlier, pea gravel is often confused with other, similar materials such as crushed stone or crushed granite. Pea gravel is naturally much smoother than both these alternatives, which usually makes it more pleasant to walk on. It's often more colourful and it is also typically a cheaper option.

Is sand or gravel better for drainage?

Your project's unique requirements will determine whether sand or gravel is better. Sand could be ideal for promoting plant growth and improving soil drainage. Gravel with larger particles provides more stability and better water flow for construction operations or heavy-duty drainage systems.

Is #57 gravel good for drainage?

Versatile Size: The 1/2 inch to 1 1/2 inch size range of #57 gravel suits various construction and landscaping needs. Effective Drainage: Due to its porous nature, # 57 Stone allows water to flow through, preventing pooling and erosion.

What is the best underground drainage pipe?

In short, pvc drainage pipes are the best option for your underground drainage system.

Which pipe is not recommended to be buried underground?

Cast Iron

Despite the heat resistance and noise-dampening properties of cast iron, it's not as suitable for underground water supply as newer materials. Cast iron is not resistant to corrosion, which can compromise the quality of the water supply and damage the integrity of the piping, leading to leaks and breaks.

What is the old GREY plumbing pipe called?

Polybutylene pipe was commonly used from 1978 – 1995 and is a gray flexible pipe. PEX is a plastic flexible pipe that comes in white, blue, orange, red and a translucent milky white clear. This piping came about to replace polybutylene plumbing.

Why is underground drainage pipe orange?

I've always understood the reason orange could <u>only</u> be used underground was that it wasn't UV-stabilised and would deteriorate quickly in sunlight. So, if you were to use it above ground, the BCO would be quite cross...

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