Quality of Roof-Harvested Rainwater for Irrigation of Crops by Family Farmers in Brazil

The efficiency of family farmers irrigation is conditioned by several factors such as good quality water supply. In this context, it was to evaluate the salinity and physical, chemical, and bacteriological characteristics of water harvested from roofs for irrigation of crops by family farmers in Brazil. The experiment was conducted at the Federal Institute Goiano, in Rio Verde, Goiás, Brazil. The rainwater collected on the roofs was sent through vertical and horizontal conductors to the storage tank, which has a capacity of 5000 L. The risk of salinity, pH, turbidity, conductivity, color, total dissolved solids and thermotolerant coliforms during 13 precipitation events was analyzed. Rainwater was classified as water with no salinity problem (EC < 0.7). The variation of the electrical conductivity (EC) and Total Dissolved Solids (TDS) were similar during the collection period, with mean values of 0.05 dS m-1 and 29.72 mg L-1 for EC and TDS, respectively. The pH of the rainwater presented little variation, presenting a mean of 7.37. The mean value of the color of rainwater was 11.45 PtCo L-1, while the turbidity averaged 4.89 UT. During the period of rainwater harvesting, it was observed absence of thermotolerant coliforms in all samples. It is concluded that rainwater does not present restrictions on the risk of salinity and that all physical-chemical and bacteriological parameters analyzed are within the limits allowed by Resolution 357/2005 of CONAMA, indicating the propensity of this type of water for irrigation.