3 Examples of Building a Rainwater Storage Tank

Learn how to build your own rainwater storage tank with these practical examples.
By Taylor

Introduction to Rainwater Harvesting

Rainwater harvesting is a sustainable practice that allows you to collect and store rainwater for various uses, such as irrigation, toilet flushing, and even drinking (with proper filtration). Building a rainwater storage tank is an excellent way to conserve water, reduce your utility bills, and promote environmental sustainability. Here are three diverse, practical examples of building a rainwater storage tank that you can try at home.

Example 1: DIY Barrel Rainwater Storage System

This example is perfect for those who want a straightforward and cost-effective solution for collecting rainwater. Using a simple rain barrel, you can easily harvest rainwater from your roof.

Start with a large, food-grade plastic barrel, which can often be found at local hardware stores or online. Position the barrel under a downspout from your gutter system. You may need to elevate the barrel using cinder blocks to allow gravity to help with water flow.

Next, cut a hole in the top of the barrel that fits around the downspout. To prevent debris from entering the barrel, install a mesh screen over the opening. This will keep out leaves and insects, ensuring your harvested water remains clean.

Finally, add a spigot near the bottom of the barrel to make it easy to access the stored water for your garden or other uses.

Notes: To improve the filtration system, consider adding a first-flush diverter that will discard the initial dirty water that comes off the roof during rainfall. You can also connect multiple barrels together for increased storage capacity.

Example 2: In-Ground Concrete Rainwater Storage Tank

For those looking for a more permanent solution, an in-ground concrete rainwater storage tank is a robust option. This type of tank can hold a larger volume of water and is less susceptible to damage from the elements.

Begin by selecting a suitable location in your yard, away from tree roots and under areas where rainwater runoff is plentiful. Dig a hole that’s approximately 6 feet deep and wide enough to accommodate a pre-cast concrete tank or a tank made from poured concrete.

Once the hole is ready, install a base layer of gravel for drainage and then position the tank. If you’re using a poured concrete tank, make sure to construct forms and pour the concrete to create the walls and base of the tank.

Next, connect a pipe from your gutter downspout to the tank. Ensure that you install a filtration screen at the entry point to keep out leaves and debris.

Finally, install an outlet pipe at a low point on the tank to allow gravity to pull the water out for irrigation or other uses.

Notes: You can enhance the system by installing a pump to move the water to higher areas in your garden or home. Also, consider using a rain gauge to monitor how much water you’re collecting.

Example 3: Repurposed IBC Tote Rainwater Storage Tank

If you’re looking for a creative and eco-friendly solution, consider using a repurposed Intermediate Bulk Container (IBC) tote as your rainwater storage tank. These large plastic containers are often available for free or at a low cost from local businesses.

Start by cleaning the IBC tote, ensuring that it’s free from any chemicals or contaminants. After cleaning, position the tote under your gutter’s downspout. Similar to the barrel system, you may want to elevate the tote to facilitate water flow.

Cut a hole in the top of the tote and cover it with a mesh screen to keep debris out. You can also add a spigot at the bottom for easy water access, along with a hose attachment.

To further improve your system, consider adding a rain diverter that connects to your downspout, automatically directing rainwater into the tote while keeping the rest of your drainage system functional.

Notes: IBC totes can hold a significant amount of water, making them a great option for larger gardens. Ensure that your tote is UV-resistant if it will be exposed to sunlight, or cover it with a tarp to avoid algae growth.


With these examples of building a rainwater storage tank, you can choose the best approach to suit your needs and resources. Not only will you contribute to water conservation efforts, but you’ll also enjoy the benefits of free, collected rainwater for your home and garden.