Chances are you live in a community where water is readily supplied. And even if you experienced last summer’s drought conditions, you probably didn’t have to worry about water for your shower, dishes or drinking. So why should you consider doing rainwater harvesting? Because water is our most precious resource and while water scarcity may not be an issue where you live now, it could be in the future.
What is rainwater harvesting?
Simply put, rainwater harvesting, or capture, is the collection and storage of rainwater for future use. It’s a practice that has been used by cultures throughout the world for at least 4,000 years, and in the United States, most households harvested rainwater to wash clothes and water gardens until the past century or so. The use of this process has declined in recent decades with the development of reliable water supply systems and public water utilities.
Rainwater harvesting provides an alternative to the use of pure water for non-potable use, helping to lessen the strain on the aquifers that provide our fresh drinking water supply. This decreases the demand for treated tap water, helps assure that water is available when needed, reduces the effects of water bans by supplying additional water during dry months, and decreases the need to import costly water from elsewhere – which, in turn, helps save money on your utility bills.
Rainwater is naturally soft and free of added chemicals that are often found in tap water, making it healthier for plants and gardens. And since lawn and garden watering make up nearly 40% of total household water use during the summer, harvested rainwater can supplement the water used for your landscaping needs. It’s also great for washing cars and other vehicles, as there’s no spotting.
Rainwater capture is also a great stormwater management solution, for it helps reduce flooding, soil erosion and water pollution. For example, in areas where the ground is already saturated, or in areas where rain is scarce and the ground is hard, water can flow across the ground, picking up numerous pollutants such as oil, pesticides, animal waste and trash. This polluted rain water then flows into the storm drains and ends up in our lakes, rivers and oceans. The same holds true for metropolitan areas where the ground can be covered with hard surfaces such as asphalt or concrete and there are few areas where the water can sink into the ground.
Best of all…this water is free! If you live in an area with an ample amount of rainfall, you can capture and use that free water for use in your home and garden. The only cost to you is the cost of your collection system.
Collection Systems
There are many ways to capture rainwater for use at your home or business. Regardless of which collection system you choose, your basic domestic rainwater harvesting system will include the following:
- Catchment surface. In most cases, this is the roof.
- Gutters and downspouts, which channel the water from the roof to the tank.
- Filters to remove debris and dust from captured rainwater before it leaves the roof. These can include leaf guards for the gutters, or strainer baskets that slip into the drop outlet of a downspout. Both will remove the larger debris. Installing a first-flush diverter will route the first flow of water from the roof away from the storage tank, ridding the system of additional contaminants.
- Storage tank such as a rain barrel. You can purchase a rain barrel designed for this purpose, or build your own out of a large container such as a 55-gallon drum.
The most commonly-used method of capturing rainwater is to place a large catchment tank such as a rain barrel at the end of a downspout. Whether you plan to purchase a rain barrel or make your own, it’s important to make sure your barrel includes several key elements. First, all rain harvesting systems should have a tight-fitting lid; an uncovered barrel of water is an accident waiting to happen for children and animals alike. Second, the barrel needs a well-sealed filter or screen on top. This will keep out mosquitoes, leaves and other debris, while allowing the water to flow into the barrel.
In addition, the barrel should have a spigot 1-2 inches from its bottom, which will be used to drain the water. There should also be at least one overflow hole or pipe near the top of the barrel. Excess rainwater from the overflow should be directed away from the house, as too much water can damage the house’s foundation. Finally, if you’re building your own rain barrel, the best container to use is a 55-gallon plastic food-grade drum – preferably never used. Clean and rinse the drum thoroughly. Never use a drum that’s held toxic chemicals or petroleum products.
Keep in mind that your barrel will be very heavy when full, as water weighs about eight pounds per gallon. Therefore, it’s important to build a stable, level platform to support the weight of your barrel. Cinder blocks are an excellent choice for this platform, as they will allow your rain barrel to sit high enough off the ground for you to place a bucket or watering can under the barrel’s spigot. Also, water flow is improved with gravity, so unless you plan to install a pump to help drain the water, the barrel will need to be elevated off the ground.
The barrel should be placed under a downspout on your roof’s gutter system. You will most likely need to adjust your downspout to direct water run-off into the barrel. The downspout can end several inches above the barrel with the water entering through a screen at the top of the barrel, or it can be configured to enter directly into the barrel.
The average roof size in the United States is around 1,000 square feet. For every inch of rain that falls on a catchment area this size, you can expect to collect approximately 600 gallons of rainwater. That’s a lot of water! If you’d like to capture more of this water, consider connecting two or more barrels together, or placing rain barrels under more than one downspout.
Looking for a rainwater harvesting system?
Here are a few recommendations.
If you’re looking for a tank that will fit in tight spaces, an excellent choice is the Rainwater HOG. This space-saving, modular tank is only 9.5 inches deep, yet holds 50 gallons of water. It’s made from recyclable plastic and can be easily connected to additional tanks for more rainwater storage.
Rain Reserve manufactures customizable and expandable Build-a-Barrel kits that can be built into five different shapes, holding anywhere from 50-100 gallons of water. The kits come complete with a Rain Reserve Diverter Kit, which diverts the flow of rainwater from your gutter into the rain barrel. The Diverter Kit is also sold separately for use with other rain harvesting systems.
Commercial and institutional buildings require the installation of more sophisticated collection systems. Water Harvesting Solutions focuses entirely on this market and offers a choice of large-scale harvesting systems.