Can You Use a Cistern for Irrigation Purposes?

Sizing a Cistern for Irrigation

When sizing a cistern for irrigation purposes, you need to consider the water requirements of the plants, the climate, and the efficiency of the irrigation system. A general rule of thumb is to size the cistern to hold at least 1-2 acre-feet of water per acre of irrigated land, depending on the crop type and climate. For example, a 1-acre cornfield may require 1.3 acre-feet of water per growing season.

Understanding Cistern Capacity and Yield

Cistern capacity refers to the total volume of water the cistern can hold, while cistern yield refers to the amount of water available for irrigation after accounting for evaporation, infiltration, and other losses. To estimate cistern yield, you can use the following formula: Yield (gallons) = Capacity (gallons) x 0.7 (efficiency factor) x 0.9 (water conservation factor). For example, a 10,000-gallon cistern with an efficiency factor of 0.7 and a water conservation factor of 0.9 would yield approximately 6,300 gallons per year.

Designing a Cistern for Irrigation

When designing a cistern for irrigation, you should consider factors such as water table depth, soil type, and slope to ensure that the cistern is properly sized and located. You should also design the cistern with a float valve or other type of water level sensor to prevent over-drafting and ensure a steady water supply. In addition, you may need to add a pump or other type of irrigation equipment to distribute water from the cistern to the plants.