How to Build a Retaining Wall in Water

Building a retaining wall in water can be quite a challenge, but it is possible with the right tools and materials. Retaining walls are an excellent way to protect your property from flooding and erosion. They also add aesthetic appeal to any landscape.

How to Build a Retaining Wall in Water

This guide provides information on how to build a retaining wall in water, including what you need to know about the materials, tools, and techniques used.

Tools and Materials You Will Need to Build a Retaining Wall in Water

  1. Gravel
  2. Sand
  3. Retaining wall blocks or bricks
  4. Wooden stakes
  5. Shovels, picks, and rakes
  6. A level
  7. Garden hose or pipe 
  8. Mortar mix (if using blocks or bricks)
  9. Tamper/plate compactor (for tamping down the gravel and soil)
  10. String or twine
  11. Hammer and nails (for attaching wall blocks/bricks together) 

 Step-by-Step Guidelines on How to Build a Retaining Wall in Water

Step 1: Determine the Size and Shape 

The first step is to determine the size and shape of your wall. Take accurate measurements and use a garden hose or pipe to mark out the area. You should also consider the topography of the area, as well as existing underground utilities, and choose a design that fits all the constraints.

Step 2: Dig Out and Level the Foundation

Once you have determined the size and shape of your wall, you need to dig out and level the foundation. Use a shovel to dig down about 8-10 inches into the soil. Make sure to remove any large rocks or debris from the area.

Step 3: Add Gravel and Sand 

Now that you have the foundation dug out and leveled, it is time to add gravel and sand. Spread a layer of gravel about 4-6 inches thick on the bottom of your excavation. Make sure to spread it evenly using a rake or shovel. Then add a layer of sand, about 2-3 inches thick, on top of the gravel. You can use a level to ensure that your wall is perfectly level before tamping it down.

Step 4: Tamp Down Gravel and Sand 

Use a Leveler to Check

Once you have added the gravel and sand, use a tamper or plate compactor to tamp it down. This will help create a solid base for your wall and make sure that it is level.  Use a level to check that your wall is even before moving on to the next step. While tamping down the gravel and sand, it is also important to create a slight slope or “batter” in order for water to run off.

Step 5: Add Retaining Wall Blocks or Bricks 

Now you can start adding the retaining wall blocks or bricks. Make sure to check each block/brick for any damage or defects before starting. If using blocks, use mortar mix to attach them together. If using bricks, use a hammer and nails to attach them together.

Step 6: Add Backfill and Optional Landscaping 

Once you have completed building your wall, you can add a backfill around the base of it. This will help ensure that the wall stays in place and is strong enough to retain the water. You can then add optional landscaping around it, such as rocks and plants, to complete your project.

With the right tools and materials, you can successfully build a retaining wall in the water. Just be sure to take all necessary safety precautions when working near or in water. Good luck!

Additional Tips and Tricks to Build a Retaining Wall in Water

Use Landscape Fabric
  1. Before building your wall, make sure to check the local zoning codes and regulations in your area. Some areas may have restrictions on how close you can build a retaining wall to a body of water.
  2. When building a retaining wall near a water source, use pressure-treated lumber or other materials that are designed for wet areas.
  3. Make sure to properly slope the retaining wall away from the water source and towards the shoreline so that water can flow away from it. This will help prevent your wall from becoming too saturated and breaking down over time.
  4. To avoid creating a dam, ensure that there is an opening at the base of the wall to allow water to flow through.
  5. To make sure your retaining wall stands up to the elements, use a waterproof sealant or coating on any exposed wood. This will help protect it from damage due to moisture and weathering over time.
  6. Ensure that the soil behind your wall is properly compacted. This will help keep it from settling over time, causing the wall to shift or collapse.
  7. Use a mix of rocks, stones, gravel, and sand when building your retaining wall to make sure that it is properly reinforced and stabilized.
  8. If you are using concrete blocks for your retaining wall, make sure to use landscape fabric between each block to prevent weeds and grass from growing through.
  9. Make sure to check your wall regularly for signs of settlement, erosion, or cracking that could indicate a problem with the structure. If you notice any issues, take steps to address them as soon as possible to avoid major damage down the road.
  10. Finally, it is always best to consult a professional for any large-scale projects such as this one. They can provide you with the advice and guidance needed to ensure your wall will last for years.

By following these tips, you can ensure that your retaining wall in water will be both strong and long-lasting. With a little effort and the right materials, you can create an attractive and functional feature that will add beauty to your outdoor space.  Good luck!

Precautions Need to Follow for Building a Retaining Wall in Water

Construct a Drainage System
  1. Make sure you are aware of the local building regulations and codes before you start constructing a retaining wall in the water. 
  2. Use strong, durable materials that can withstand the pressure of water for effective construction. 
  3. Build your retaining wall at least two feet higher than the highest possible water level to prevent overflows from occurring. 
  4. Make sure your wall is sloped in such a way that the water can flow away from the structure and not towards it. 
  5. Construct a drainage system or install filters along the base of the retaining wall to ensure any excess water can be diverted quickly and effectively to prevent flooding. 
  6. Test the soil before you install the retaining wall to ensure that it is of good quality and can support the weight of the structure. 
  7. Avoid using wood in water as it can be easily eroded by water or damaged by termites over time. 
  8. Install a waterproof sealant along the base of your retaining wall to ensure no water can seep through. 
  9. Make sure the retaining wall is constructed at least two feet away from nearby structures and buildings to prevent any damage due to flooding or erosion. 
  10. Monitor your retaining wall on a regular basis to make sure that it is stable and secure, and that there are no signs of damage or wear and tear.

By following the precautions mentioned above, you can easily build a retaining wall in water that is strong and durable. Take your time to ensure that everything is done right and you will have a structure that will last for years to come. Thank you for reading!

Frequently Asked Questions

Is It Possible to Build a Retaining Wall in Water? 

Yes. Building a retaining wall in water is possible, but it requires specialized materials and techniques. The wall must be built using waterproof materials such as concrete blocks, treated wood, or specialty plastic products designed for building walls in wet areas. Additionally, the wall must be properly sealed and reinforced with rebar to ensure its stability and longevity.

How Do I Make Sure My Retaining Wall Is Waterproof?

To make sure your wall is waterproof, the materials used should all be designed for wet areas. Additionally, you should use a waterproof sealant over the surface of the wall before installing it to ensure no moisture can penetrate the surface. Additionally, using a rebar or steel mesh reinforcement will provide extra strength and stability as well as protection from water damage.

Are There Any Special Techniques Needed When Building a Retaining Wall in Water?

Yes. When building a retaining wall in water, it is important to take extra care when designing the wall. The area should be sloped away from the wall and drainage systems should be added to help prevent water build-up. Additionally, proper backfilling material should be used to give the wall support and stability. Finally, a waterproof sealant should also be applied to all of the joints in the wall to prevent leaking.


Building and knowing how to build a  retaining wall in water requires extra care and specialized materials. It is important to use waterproof materials, waterproof sealants, and proper backfilling material to ensure the wall’s stability and longevity. Additionally, using rebar or steel mesh reinforcement will provide extra protection from water damage. With these tips in mind, building a retaining wall in water is possible and can be a great way to protect your property from flooding.

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