Pros And Cons Of A Rock Downspout Catch Basin Under Gutters

Many homes have a downspout that carries water from their roof to the ground. However, water might remain around the foundation if there isn’t an extension or drainage system to carry it away. Luckily, there are many alternatives to creating a downspout extension, and one of them is the rock downspout catch basin extension.

Rock downspout catch basins are viable options as long as proper liners are placed underneath, boarders are constructed to constrain the flow of water, and proper slope is maintained. Water should be directed to at least 15′ away from a structure’s foundation.

In this article, I will be reviewing some pros and cons of using a rock downspout extension under the gutter. I will also be discussing what to put under a gutter downspout as well as the prevention of downspout washout.


Pros and Cons of a Rock Downspout Catch Basin Under Gutters

Rock is one of the oldest and most useful resources for landscapers and architects because of its unending building applications. Sometimes it is used correctly and sometimes it is not.

Water and rocks have a unique relationship. Though gravel of differing sizes supports a considerable amount of weight above most any soil type, it allows water to pass straight through it nearly unhindered.

It has some features that make it quite suitable for drainage constructions. So, below are some pros and cons of using rocks for downspout extension:


  • Using rocks will make your under gutter aesthetically pleasing.
  • Rocks can prevent weed, shrubs, or soil mounds from growing as these things make the place look untidy.
  • Laying gravel under downspouts will prevent soil washout and erosion.
  • Rocks absorb heat from sunlight and then radiate it at night when there is ice that needs to be melted. This process is necessary for water to move faster.
  • Rocks are sometimes an affordable option especially when getting them locally.
  • Rocks prevent the excess gathering of water, making it difficult for termites and other pests/insects to survive.


  • It might look unsightly when not adequately maintained due to movement and weeds.
  • Rocks may not be suitable for permanent downspout extension.
  • Rocks allow water to move through it directly to the soil under a downspout.
  • Home foundations are not protected from infiltration with gravel allowing downward flow of water.
  • Gravel can slow water movement, but does not adequately direct its flow.

Arguably one of the main uses for gravel or rock under a downspout is to stop washout of mulch or soil due to fast moving water coming from the gutters. The cons though can outweigh the aesthetics if it is not done properly.

The water needs to be moved anywhere from 15′ to 20′ away from the house. This will require some extra planning and components to a rock or gravel downspout basin.

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How Do You Make A Rock Downspout Basin?

As we have discussed, gravel and rock will not stop water from seeping down to your foundation and causing problems over time. There are some extra steps that you will need to take if you are set on using rock under your downspouts instead of other options.

To make a rock downspout basin under a gutter discharge it is important to use a properly thick underlayment that can catch the water under the gravel and send it on its way. With the help of a properly sloped area and gravity, this could remove the need for plastic pipes or tubing.

If a rubber or plastic membrane like a pond liner is not used, you are setting yourself or future owners of your house up for a huge problem.

I know this first hand, having bought an historic home that had water directed directly to the foundation for decades.

Here the guys at Master Services are installing helical piers to correct the sinking foundation issue.

The sinking foundation and slab under our home was due to downspouts that ran directly into the ground for many years pouring 600 plus gallons of water into the soil around the exterior footers every time it rained. This caused doors not to close, wall cracks, and at one point a collapsed sewer line under the house.

We inherited these problems from the lack of downspout treatment and the particularly susceptible soil it sits on. We had to have a total of 16 helical piers put in around particularly troublesome sections of our house. This is all thanks to former owners not taking their drainage problems seriously.

Just because you like the way gravel or rock looks under your downspouts, or the fact that it stops surface soil erosion doesn’t mean that the unseen damage water is doing near your foundation isn’t happening.

It is extremely important to get water far away from your house. So, here is a couple of important things to be sure you do in order to make your rock or gravel downspout basin functional and not just aesthetically pleasing.

  1. Ensure that there is fall or a decline in ground elevation away from where your gutter downspout reaches the ground.
  2. Line the areas near the structure where water can reach with a strong pool or pond liner.
  3. Add some sort of boarder to the area to direct the water flow down and away from foundation areas.
  4. Make sure that water disperses at least 15 feet away from the house foundation.

If these are not possible in your situation, it may be better to use other options for collecting and leading away water flow from your roof.

What Should You Put Under Gutter Downspouts?

Gutter downspout is essential for eliminating rainwater from your roof and transporting it away from the building foundation. The key word here is ‘away’.

The problem with simply adding any type of rock or gravel underneath a downspout is that it will not move water away from the very thing you are attempting to protect. Once the water is in a pipe, or in this case a gutter, it is not advisable to let it out until it is a safe distance away from a building’s foundation.

Also, there are many things you can put under the gutter downspout. Here are some of them.

Rain Tank

A rain tank is usually placed under the gutter downspout to collect water to be used later. You can further use the water collected to irrigate your flower bed, garden or do some other clean-up.

When setting up the rain tank, you should ensure that the downspout outlet is many inches (more than the height of the tank) away from the ground.

Aluminum Extension

Putting an aluminum extension under a gutter downspout will prevent your building foundation from being weak because this extension will carry water far away from the foundation. 

An aluminum extension is easy to fix and a good solution for a downspout. It also allows a very smooth movement of liquid.

Some don’t like the look of such a long metal gutter pipe extending away from their house. There is a hinge that can even be applied to pull the extension up and out of the way until it rains or in order to mow around the area. The hinge is called the Zip Hinge Downspout Gutter Hinge and can be found on Amazon.

The same thing can be accomplished with a buried pipe. We will discuss this later.


A StealthFlow can be likened to an extension for downspout gutter because of its design.

It is made with plastic, and you can place it underground. Some people prefer it to the aluminum extension because you can hide it. 

Rollout Drain Sleeve

It is a kind of flexible downspout extension that operates so that it rolls out when water flows in and rolls in when water stops flowing in. 

This may not be the best option for you as they are not made of high-quality plastics. However, if you find that you like the mechanism of this tool, then you can opt for it.

Splash Blocks

Splash blocks are another option to put under the gutter downspout. 

They are designed in a shape that makes them suitable to get rid of water dropping from your downspout. The splash blocks come in different materials, including plastics and metals. 

It can be a good option if your budget is not very high.

Buried Drain Pipe

Using the buried drain pipe is another guaranteed method of keeping the water log away from your building. 

It is an excellent downspout extension option, but the only challenge is that you might find it stressful digging down the trench. However, you can hand the job over to a landscaper.

This is by far the most effective and aesthetically pleasing way to move water away from your home. It is the way I have done it for my home and for many irrigation solutions for others.

How to Prevent Downspout Washout

Downspout washout can be an unpleasant event, especially when you notice it is wiping out your flower bed. 

Therefore, if you wish to avoid such a scenario, you can use some of the measures below.

Lay Rocks Under the Downspout

Rocks are so tough and dense that they cannot be easily washed out by gutter downspout. 

Laying them so that water slopes away from your home will prevent soil washout. You can also use them to make some kind of extension.

Use a Catch Basin and Drain Tile

An excellent way to prevent a downspout washout is by integrating a drain with a catch basin underground so that water flows from the downspout to the drain.  Although, you need to create an extension with rock leading the water from the downspout to the drain. 

You can also connect a pipe to the basin to empty the catch basin each time it is full.

Splash Blocks

A splash block is attached as an extension to help disperse water from the downspout. This will prevent any form of washout or erosion. 

Something interesting about splash blocks is that they are easy to set up, and you can get them at any local home improvement around you.

Use a Long Downspout Extension

When using an extension, you should also take note of its length. Using a short downspout extension is as good as having no extension because it might eventually wash out the soil. 

A good extension should be at least four feet away from your building.

Plant Grasses Close to the Downspout

Short grasses have strong roots to withstand any kind of water pressure coming from the downspout. 

Therefore, planting them is a great way to prevent washout as well as retain the soil’s nutritional properties. These short grasses will also add to the beauty of the environment, especially when you trim them regularly.

Plant Cover Crops

You can also choose to plant cover crops to cover the soil. They are fantastic alternatives to grasses. These crops help manage soil fertility and quality, water, and other properties. Buckwheat, rye, oats, and barley are great examples of cover crops options.

Keep in mind that whichever cover crop you plant should have strong roots.

The Final Touches On Rock Downspout Catch Basins…

There are ways to use rocks or gravel under downspouts, but it takes a couple of steps to get it right.

There are also other ways to deal with downspout flow. The important thing is to get it away from the foundation at around a safe 15′ to 20′.

If you are set on using rock or gravel, then doing it right can make all the difference.

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Mathew Booe

Mathew has worked in landscaping professionally for over 10 years. He is a grandpa and frequently interviews other experienced landscapers and lawn care experts who are also grandpas for these articles.

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