Rainwater Harvesting by PJ LaRue Smith
Depending upon where one lives in Hunt County, the average annual rainfall can range from 35” to 44”. Keep in mind however, that this is the average rainfall for this area each year, not what actually falls every year. Very dry years might have rainfall amounts in the teens and in extremely wet years it might rain 60 plus inches. With variations like this, the saying, “plan for the worst, and hope for the best” certainly applies!
Historical documentation shows that man has been collecting and transporting rainwater for his use since ancient times. While technology, society, etc. have changed, our need for water, both for ourselves and the crops we grow, have not.
Rainwater collection begins with a catchment area – any surface from which water can be collected. Roofs (metal, shingle, or wood) and pavements/concrete (driveway, sidewalk) shed water rapidly and are considered the optimum catchment areas due to their hard, smooth surfaces.
Soil, as many a rancher/farmer knows, is a viable catchment system. Particularly if it is clay-based, as it will shed water quickly if the rain is falling fast enough. (Sandy soil, however, will absorb a considerable amount of water, and often requires a modified method of collection.)
From the catchment area, water is moved (distributed), typically via gravity, to a holding area. These distribution systems need not be elaborate. Water dripping from the edge of a roof to a planted area or a diversion channel located directly below the drip edge is an extremely simple method of moving water to a desired location. Gutters and downspouts, sloped sidewalks, hillsides, along curbs, and through ditches are all fairly easy to employ as distribution systems. (Note: For sandy soil, lining a run-off ditch with an impermeable material (i.e. plastic), will increase the amount of water movement.)
Now that the water has been caught, and is moving, where does it need to go? A simple “landscape holding area” can be a place that typically holds water after a heavy rain, a small pond, stock tank, or lake. These types use soil to harness water for future use. Maintaining and building such holding areas can be somewhat expensive as well as labor intensive. However, if done correctly and properly maintained, this type of water holding system will be useful for many years, add beauty to the landscape, and be a harbor for a variety of wildlife.
Man-made “landscape holding areas” are typically storage containers made of polyethylene, fiberglass, wood, concrete or metal which can be placed either below or above ground. While below ground placement will incur costs related to excavation and require some sort of pump system to move water from the tank into the landscape, their visual footprint is minimal. Above-ground tanks require pad preparation (to maintain the stability of the tank); generally rely on gravity to move the water from the tank to the needed area(s) of the landscape; and make a large visual impact in the landscape. The visual impact of above-ground tanks can be reduced by the use of fencing material, plants, or a combination thereof.
Harvesting rainwater can be a small, simple, and relatively inexpensive operation, or a large, elaborate, high-cost one, depending upon the amount of water that is to be harvested and the topography of the landscape. Regardless of size, however, the following benefits certainly argue the case for harvesting rainwater: reduces water bill cost; reduces demands on the municipal water supply; efficiently uses a valuable resource; and reduces flooding, erosion and contamination of surface water. Rainwater is also free of salts and other minerals that harm root growth – making for much healthier plants and fewer disease problems.
Collecting rainwater, even in a small way, is a win-win situation – consider giving it a try this season!