Cost Comparison and Hydraulic Design of Four Types of Residential Rainwater Harvesting Systems for Small Rural Communities, Considering Natural or Anthropogenic Climate Change Factors

Abstract

This document presents the technical description and cost comparison of four rainwater harvesting systems for homes, the method for its hydraulic design and an equation to estimate the minimum catchment area, with the goal to supply drinking water to segregated small communities in Mexico considering climate change effects, both natural and anthropogenic. The four Rainwater Harvesting Systems (RHS) introduced in this work are the following: two rigid, one system built with ferrocement and the other built with clay bricks, and two flexible: one is a commercial collector while the other is a system built with a 3/8-inch reinforcing bar mesh and covered with a linear low-density polyethylene geomembrane. The RHS consist in cylindrical containers built with diverse materials, and in the case of rigid RHSs, they can store up to 50,000 liters of water. Also, rigid RHSs have a longer useful life and are more resistant than flexible RHSs, but their cost is notably higher. Rigid RHSs compete in price with commercial rainwater harvesting system brands like Rotoplas , but commercial RHSs disadvantages are their lower durability, storage capacity, and resistance. On the other hand, flexible RHSs are less durable than rigid ones, although, in the case of the rainwater harvesting system made with a 3/8-inch reinforcing bar mesh, the system can be rebuilt and reused and the cost is much lower. The design of the collectors takes into consideration the climate variability of the study area, natural or anthropogenic.