Harvesting Rainwater

In its essence harvesting rainwater consists of three components: the capture, diversion and the transfer of rainwater. Storage of rainwater is another possibility. This is most commonly done for the purpose of irrigating gardens and landscaping. Rainwater contains high levels of nitrogen and other nutrients not found in treated water. It is better for your plants and will produce healthier, hardier blooms.

Harvesting rainwater is also good for the environment. It helps to conserve the drinking water supply, therefore reducing your cost as well. It is especially useful during dry periods when your foliage needs it most. The diversion of rainwater prevents the soil in your garden from becoming dried up and producing possible flood conditions. The soil retains more moisture and it is not necessary to use as much water in the future therefore reducing topsoil loss.


The first requirement needed to set up a rainwater harvesting system is to establish some type of catchment area. The catchment are will provide the supply. This can be any area from which rainwater can be harvested. The best catchment areas are smooth, nonporous rooftop materials. Metal roofing is a perfect example. The size, surface and slope of the catchment area will determine the amount of water harvested. Of course the amount of rainfall is also a factor.

The second necessity is some kind of diversion and distribution apparatus. This can be as simple as rain gutters and downspouts, or it can be a sophisticated system of gates, diverters, plastic pipes and water spouts. The basic idea behind a rainwater harvesting system is that it utilizes gravity for collection and distribution of water. Hillsides, channels, ditches and sloped sidewalks can be incorporated into your system. If gravity is an issue small water pumps can be used.

A holding area is an optional third component. This can be a depression in the landscaping. You can add a moat. Soil terracing can be used also. In the case of collecting rainwater from gutters and downspouts a simple rain barrel can be used for water storage. If you are designing a new home or are landscaping or reconstructing your present one you can incorporate rainwater harvesting into the design of your home.

Observe Water Conditions

Observe your landscaping in the rain. Look for existing patterns of rainfall saturation. If you are using a rooftop catchment area you can extend downspouts to areas in need of additional water. Another idea is to plant large hardy plants where the downspout drains into the soil. You can add large rocks to basin the area and prevent erosion.

Storage of Rainwater

Because rainwater harvesting is dependent on rainfall it is not a perfect system. The use of a storage system will help balance the amount of rainwater available during dry spells. Before the water is stored it needs to be filtered to remove particles of debris.

The storage container should be covered for the prevention of mosquito breeding and algae growth. The filtering system can be as simple as a leaf guard attached to the gutter. You can also use in line filtering to remove finer particles.

Storage containers can be made out of plastic, fiberglass metal or wood. A storage system can be quite an investment. You can use an underground storage container if you are willing to add the effort and expense of excavation. You can be creative. Some less expensive choices for storage containers include large trash cans, wooden barrels, tanks, steel drums, cisterns, fish ponds and existing swimming pools.

Ideally the storage container should be at the highest point of the property. This allows the utilization of gravity in the distribution of stored rainwater. If there is no slope on the property storage should be near the area that is to receive the rainwater.

Several smaller storage containers can be placed at various places on the property. This will make water distribution easier. It will also make it easier to hide the storage containers with foliage if they are not visually pleasing.

All you need to start harvesting rainwater is rainfall and an area that can use more water. Simple harvesting systems can have almost immediate benefits for both you and the environment.

Photo by Jan Tik, Creative Commons Attribution License