Rainwater Harvesting
Water covers about 75 percent of our planet, so on the surface level (pun intended) there seems to be an abundance of this natural resource. So why bother to conserve it? Because less than 1 percent of the water we have is available freshwater.
Add to that the way we use water: Only 10 percent of the total water used by the average American is used as potable water (drinking and cooking). The rest is used for washing and showering (27 percent), toilet flushing (24 percent), washing clothes (17 percent), doing dishes (14 percent), and gardening/washing cars (8 percent). Finally, 3 percent of the total electricity used in the U.S. is used in wastewater and municipal water treatment. Bottom line: Reducing the amount of new freshwater needed to “run your lifestyle” has a significant green impact.
Water conservation is the best first step in reducing your environmental footprint related to water. But beyond that, simple rainwater systems allow you to collect and distribute the water with minimal processing, reducing your demand for new freshwater. More complex systems even can allow you to filter and treat the water for potable purposes.
This article focuses on the basics of rainwater harvesting for non-potable outdoor purposes.
The ABCs of rainwater harvesting
Collection and conveyance. The first step in rainwater harvesting, collecting rainwater and conveying it to a container, is relatively simple, since all homes have some form of water management system that involves gutters and downspouts. You can redirect the water from the drainage system into your container by simply cutting or relocating the downspout or by using an innovative diverter such as the Garden Watersaver. The benefit of using a diverter is that once your collection container is full, the rest of the water is handled by your existing downspout, directing the water away from your home rather than risking it spilling over the container and causing issues.
Filtration.: Rainwater is relatively pure, but as it runs along your roof surface and through the gutter system, it inevitably will pick up bugs and other debris. Basic filtration is necessary to ensure that you’re not collecting debris in your container or gunking up the distribution system, thus decreasing water pressure and causing an untimely failure of the system. For non-potable purposes, simple screens can suffice to filter the water, with a larger mesh screen placed at the top of the downspout and a finer mesh screen at the mouth of your storage container.
Storage. : There is a variety of storage containers available, ranging from simple and aesthetically pleasing containers, such as specifically designed rain barrels or used whiskey barrels, to complex engineered plastic storage systems. The container you choose depends largely on your storage needs and the aesthetics and functionality you require. Here are some simple tips for choosing storage containers:
Perform supply-and-demand calculations and size your storage containers appropriately. Assuming you’re using rainwater only for gardening purposes, how much water you’ll need (demand) depends largely on the type and number of plants you’re watering. How much you can collect (supply) is based on the size of your collection area (i.e., roof) and the amount of rainfall in your area. Check out the worksheets provided by Texas A&M University to calculate supply and demand.
Elevate your containers to take advantage of gravity flow and avoid the need for a pump.
Place your containers under downspouts and as near as possible to the area you’ll want to water.
Use multiple smaller containers. It’s easier to hide them with plants and garden structures.
For large areas and high demand, use several connected containers to allow for greater storage capacity.
If supply exceeds demand, make sure to allow for appropriate overflow and direct the water away from your home.
Distribution. Once the rainwater has been collected, you’ll need a means to transport it to the area you want to water. The simplest approach is to have a valve at the bottom of the collection container that allows you to collect the water in a bucket to carry it to the garden. This isn’t the most practical approach, however, when you have a large area to water or when your garden is far from the collection containers. Provided that your container is placed high enough, a gravity-fed hose, channel or drip irrigation system are simple and efficient options. Beyond that, a hand or electric pump will be necessary to transport water to the garden.
Safety and durability: As with any home project, you need to address the safety and durability of the system you’re installing. Safety of rainwater systems includes ensuring that the system doesn’t promote the breeding of insects such as mosquitoes. Especially important is preventing a drowning hazard for children or animals. Also make sure that the containers are adequately secured so they don’t create a crushing hazard. Simply cover and secure your containers well to avoid these dangers. To make sure the system will stand the test of time, choose materials that weather well and allow for easy cleaning and winterization.
For more information on creating a complex rainwater harvesting system to provide water for potable or indoor water uses, visit HarvestH2O.com or the Texas A&M site.
Rainwater harvesting network
Rainwater collection
Rainwater Recycling
Rainwater harvesting from rooftop catchments
Harvesting Rainwater for Landscape Use
Rain Barrels
Source:http://www.diynetwork.com/diy/gr_soil_water/article/0,2029,DIY_13858_5606858,00.html