We examine the sustainability of seawater desalination plants using Inclusive Impact Index light (Triple-I light). This index quantifies the environmental and economic impact of a human activity through estimations of ecological footprint, biocapacity, cost, and benefit. The seawater desalination plants we treated are a multistage flash distillation (MSF) type and a reverse osmosis (RO) membrane type in the Kingdom of Saudi Arabia. Our calculations demonstrate that the indexes for the two plants are raised mainly by large ecological footprints. By conducting a sensitivity analysis with varying a few parameters, we reveal that the total amount of water supply can largely change the sustainability of the plants, and propose that reductions in electric power consumption can be a feasible strategy to keep these plants in sustainable condition. We show that if we can supply about 40-50% of the total power consumption for the desalination plants using renewable energy sources, the sustainable operation is achievable. These percentages can be used as the target value of the introduction of renewable energy. (C) 2014 Elsevier B.V. All rights reserved.