How to DIY Rainwater Collection System

Take your garden to the next level by building your very own rainwater collection system. This system can add another level of sustainability while helping the surrounding ecosystem. Building one is more accessible than you’d think. So, why wait? You can start your DIY rainwater collection system today.

Image of a trashcan being used for a rainwater barrel collection system
Rain barrel made from a plastic trash bin

Rainwater harvesting is the process of collecting and storing rainwater for later use. It’s not only a smart and eco-friendly choice, but it’s also a great way to add to the ecosystem by utilizing the available resources.

Start your DIY rain collection system with these steps.

To begin, you’ll need one or more water storage barrels. You can purchase a new barrel online or a food storage container. Clean it thoroughly before use. If you want to be fancy, consider purchasing thermal mass rainwater barrels. These barrels work by using a thermal mass material, such as concrete or stone, to absorb heat from the sun and retain it. This is designed to keep the water in the barrel warmer during colder months.


The thermal material absorbs heat and releases it slowly over time.

Deciding the Size for your Rain Barrel

The size of the rain barrel depends on your specific needs and the amount of rainfall in your area. Generally, a rain barrel size of 50-100 gallons is ideal for most residential situations. If you have a larger property or want to store more water, you may consider a larger size rain barrel, such as 200 or 300 gallons. It’s important to consider the space you have available for the rain barrel and the amount of rainfall you typically receive in your area. Avoid purchasing rain barrels that have stored toxic substances like oil or pesticides.

Additional Materials

Next, gather the additional supplies, which can be found at your local hardware or home and garden store. These include a standard 1-inch hose spigot, Teflon thread tape, PVC pipe, uniseal, a filter, and concrete blocks.

Prepare the Foundation

To prepare for the rain barrel, level an area next to your downspout and create a layer of pea gravel for drainage. Then, stack concrete blocks to create a raised platform for the rain barrels. Take advantage of gravity by ensuring proper placement. The barrels should also be able to withstand a lot of weight to avoid collapse. Additionally, install an overflow drain in the event of heavy rain.

Install a Filtration System for Collected Rain Water

Before using the collected rainwater, install a filtration system to remove organic matter and other impurities. Choose the location where you will install the filter. This should be near the collection point for the rainwater, such as a gutter, and accessible for maintenance purposes. Purchase a suitable rainwater filter. There are various types available, such as mesh filters, downspout filters, and barrel filters, depending on your needs and budget. Cut the downspout or pipe where you want the filter to be installed, and attach the filter to the cut end.

DIY Rainwater Collection System Piping

Once you have your rain barrel cleaned and ready to go, it’s time to install the PVC fittings and hose spigot. Start by marking the PVC pipe at the 1-inch point. Next, use ground support to push the fittings onto the barrel securely. Finally, wrap Teflon tape around the threads of the hose spigot to create a tight seal and prevent any leakage. With these steps completed, your rainwater collection system will be ready to use in no time!

Ensure a Tight Seal

When creating a rainwater collection system, ensuring a tight and waterproof seal is crucial to prevent leaks and maximize the amount of water collected. This is where uni-seals come in handy. Uni-seals are flexible rubber o-rings that create a secure and tight seal between PVC pipes. By cutting PVC pipes into 5-6 inch pieces and connecting them to the barrels using uni-seals, you can create a leak-proof connection that will help you collect as much rainwater as possible. This method is not only effective but also cost-efficient, making it a popular choice for DIY rainwater collection systems.

Uni seals are rubber seals that are commonly used to seal off water inlets/outlets in rain barrels. They prevent leaks and ensure a snug fit between the barrel and the accessories. You can find different sizes and types of uni-seals at most hardware stores or online retailers. Just make sure to choose a seal that fits the size and shape of your rain barrel inlet/outlet.

Build a Rainwater Distribution System

The next step is to distribute the rainwater. Building a water distribution system can be as simple as connecting a hose to the bottom of the rain barrel, but for a more efficient setup, PVC pipes and connectors can be used to create a gravity-fed system. By gluing together PVC pipes and fittings, the water can flow from the top barrel down to the next, and so on, until it reaches the lowest barrel. This creates an equalization of water levels across all the barrels, which reduces the need for additional plumbing and pumps. A well-designed distribution system will also include valves and shut-offs to control the flow of water and divert it to different areas of the garden or landscape as needed.

Install a First Flush Diverter System

Don’t forget to incorporate a first-flush diverter system. This mechanism is responsible for directing the initial rainwater flow away from your collection tank. While you can purchase a first flush diverter, it’s also a cheap and accessible homesteading project that you can tackle on your own. All you need are simple plumbing fittings, which you can easily find at your local hardware store.

With a little bit of effort and patience, you can construct your own first flush diverter and have it up and running in no time. However, it’s important to note that an overflow is necessary to prevent flooding. Once the larger pipe is full, the diverter will start diverting the clean water to the tank or barrel for storage. By using a first-flush diverter system, you can ensure that the water collected for household use is clean and free of debris, making it a reliable and safe source of water for various purposes.

Finally, collecting rainwater for your plants can bring a whole new level of sustainability to your gardening routine. Rainwater is naturally pure and free of chemicals that are commonly found in tap water, such as chlorine and fluoride. This means that your plants can absorb the water more easily and effectively, promoting healthy growth and blooming. Additionally, rainwater has a neutral pH level, which is ideal for most plants, as opposed to tap water which can be too alkaline or acidic.

Rainwater is also a much more economical option for watering your plants. You’ll save money on your water bill and add to the ecosystem. Many communities are facing water scarcity. Therefore, by using rainwater for your plants, you’ll be doing your part to conserve this precious resource.

In conclusion, using collected rainwater for your plants is a smart and eco-friendly choice. It benefits not only your plants but also the environment and your wallet. So, if you’re looking to take your gardening game to the next level, start collecting rainwater today!

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