Retaining walls are one of the most common uses of our paving stones. Whether they’re used as a patio edge or to add depth to your yard, these structures make for both useful and attractive hardscape features. If you’re already planning how to ensure your wall stays strong and stable, you’re on the right track. Properly considering its function and how it will handle drainage is a key step in designing a retaining wall that truly lasts.
At Western Interlock, we believe in building for generations, which is why proper drainage is crucial to the overall durability of your retaining wall. In this blog post, we’re covering why drainage matters and three specific components you can implement to help your wall perform optimally for many years to come.
The reason drainage is so important in a retaining wall is simply because the lack of proper drainage is the primary reason a retaining wall can fail. If there is no relief for moisture and excess water that gets behind your retaining wall and into the soil, the soil can become too heavy and actually push over your retaining wall.
Ignoring proper drainage can lead to costly repairs down the road, so taking the time to plan your drainage system now will protect both your investment and the stability of your outdoor space.
The first component in a proper retaining wall drainage system is perforated pipe. We recommend using slitted, corrugated pipe because it is flexible and easy to use.
A perforated pipe will essentially create a highway to relieve the water behind your wall as quickly as possible. If the water has nowhere to go, it will build up behind your wall and eventually make your wall collapse.
To install a perforated pipe, first create a slight gravel ramp so water naturally flows toward the pipe. Then, direct the pipe through the block face by either cutting a notch that matches the pipe’s diameter or using a wall drain pro or spillway.
Be sure to place the pipe near the bottom of your excavated area so it can effectively channel water away.
The second key component for proper retaining wall drainage is a compacted gravel backfill. This layer adds necessary weight behind the wall, anchoring it securely into the surrounding slope or landscape. You can also use crushed open rock for additional drainage, as it helps water flow away more efficiently.
For best results, you’ll already have excavated and installed a gravel base layer as a footing for the retaining wall. We recommend at least 6 inches of compacted DOT ¾”-0 gravel under the first course of blocks.
The amount of gravel fill behind the retaining wall will vary on application, but should not be less than 12″. After each course of retaining wall blocks, backfill with gravel and compact again.
For a long-lasting solution, combine this approach with Western Interlock retaining wall blocks, designed to integrate seamlessly with proper drainage systems.
The final component you should install to ensure proper retaining wall drainage is a product called geotextile.
There are various types of geotextile, but the best kind to use behind a retaining wall is a nonwoven geotextile. This material allows water to pass through while keeping soil particles out, so your gravel backfill won’t become clogged over time. By maintaining a clean, free-flowing layer behind the wall, you help ensure proper drainage and reduce the risk of water buildup.
The addition of geotextile fabric also minimizes the risk of settling from freeze-thaw cycles. When soil seeps into the gravel, it can shift and create voids, which compromises the wall’s stability. A nonwoven geotextile maintains a cleaner drainage layer, helping your wall stay solid and better able to handle seasonal changes.
To install geotextile, first make sure your retaining wall’s footing is properly prepared with a compacted gravel base. Unroll the fabric so it covers the gravel layer at the bottom, then extend it up the back of the wall blocks. Once you’ve set the retaining wall blocks and backfilled the area with gravel, lay the geotextile fabric over the top of the gravel. The proper installation of geotextile will ensure that the water that flows through will be free of soil particles, helping your drainage system stay clear and effective.
By incorporating perforated pipe, compacted gravel backfill, and a nonwoven geotextile, you’re giving your retaining wall the best possible defense against excess water. These simple yet essential steps help ensure that your wall stays sturdy, drains effectively, and lasts for many years to come. At Western Interlock, we’re here to guide you every step of the way—so you can build with confidence and enjoy the lasting beauty of a well-planned hardscape.
For additional instructions on building a retaining wall system, be sure to check out How to Build a Retaining Wall at Home.
If you are ready to get started and choose what materials to use for your hardscape project, you can click here to make your choice from our selection of products. Also, check out our DIY with WI page for access to tutorials, guides, and more.
If you have any questions about customizing your wall’s drainage setup for your unique landscape, our team is here to help. Our team will be happy to assist you with any questions or personalized advice you need for any step of your hardscape project, from your project base to the finishing touches.
Choosing a paver can sure feel overwhelming. You have to consider size, style, thickness, color, and more. That’s why we made a short and simple quiz that asks a few questions about what you’re looking for and, at the end, provides a recommendation, or two, you can start with.
Learn More
© 2025 Western Interlock. All rights reserved. Web Design by Structure.
