Wastewaters from the fresh produce processing industry are high in solids and organic matter requiring adequate treatment prior to disposal or recycling. Characterization of the processing wastewater, also referred to as wash-water is challenging, as the quality is a function of the produce. Analysis of water quality parameters, such as total suspended solids, total solids, total dissolved solids, chemical oxygen demand, biochemical oxygen demand, total nitrogen, total phosphorus, ammonia, and electrical conductivity from different fruit and vegetable operations were analyzed to develop the innovative power function models and ranking system to estimate wash-water quality. The developed models take the form of Y = a(x)b, where Y, a, x, and b are estimate, scale, rank, and location parameters, respectively. The location and rank range from −0.65 to −3.18 and 0.05 (worst water quality) to 1, respectively, while the scale parameters are highly variable. Average and standard deviation estimation models show a very good fit for washing only (R2 > 73%) and washing with processing (R2 > 79%). The models and ranks highlight the degree of treatment required to address protection of surface and ground water and make the water quality conform to regulatory standards, benefiting watershed managers, government agencies, consultants, farmers, producers, processors and technology providers.