Rainwater Catchment System

Like many other Texas farmers over the past 150 years, we chose to develop a consistent supply of water by capturing and storing rainwater.

In many parts of the world, water for domestic use, irrigation and livestock is difficult to obtain. Ground water from wells may be nonexistent or too difficult to reach, and there may be an absence of reliable surface water, such as a pond or stream. This is the case with our four-acre model homestead. Because the ground water is over 1200 feet below the surface, it is therefore too costly and difficult to obtain, and there are no creeks or ponds close enough to utilize. In this part of Texas we average approximately 32" of rain per year. However, this amount of rain is usually unevenly distributed throughout the year. The average annual rainfall amount sometimes comes in just a few large rain showers with extended periods of little or no rain in between. Our rainwater catchment system provides a more consistent supply of water for our garden and livestock during the dry periods.

The roof ot the restored LaRue Barn catches the rain that runs through the gutters and into the 10,000-gallon cistern that stores the water. A significant amount of water can be captured from a catchment area such as this barn roof. One inch of rainfall on a 1000- square-foot area can yield 623 gallons of water. If you apply this formula to calculate the potential of a catchment area, you must use the area of the building’s foundation, its footprint, rather than the square footage of the roof area. (A steep roof will have a greater amount of square footage than the foundation.) The LaRue Barn is 30' by 40', which is 1200 square feet. Using the above formula (1200 x .623), one inch of rain on the barn roof will yield 747 gallons of water, so 13 1/2 inches of rain will fill the10,000-gallon cistern.

In the pasture, located away from any structures or trees that would hinder the flow of wind and cause turbulence, we installed an Aermotor windmill. Water flows from the 10,000-gallon cistern to a small cistern under the windmill. The windmill then pumps the water through another underground pipe to a 1600-gallon cistern at the top of the 20-foot-high water tower located between the Homestead Cabin and the barn. One foot of rise (height) provides .4335 pounds of pressure per square inch (psi). Therefore our 20-foot-high water tower will give us almost 9 psi, plenty of pressure to run our drip irrigation system.

Our simple drip system in the garden uses water more efficiently and requires only 6 psi to operate. In addition, we cover the garden with mulch, which slows down evaporation from the soil and helps to hold the moisture in the soil. Our 10,000-gallon cistern, plus the 1600-gallon tower cistern, will give us a month's supply of water at the rate of one inch of water per week on the forty-two 10-square-foot garden beds.