A top-down approach to estimate global RO desalination water production considering uncertainty

Desalination is one of the promising methods to address the water shortage, especially for the coastal areas. To understand the present status of the desalination industry, it is of importance to accurately estimate the magnitude of water production of the desalination industry. However, traditional bottom-up approaches to estimate desalination water production magnitude are often relying on data of individual water treatment plants and may lead to contradictory results since it is extremely difficult to obtain accurate desalination water production data of most water treatment plants. Considering RO modules are manufactured by limited major suppliers globally, we propose a top-down approach to estimate global RO desalination water production. The approach is to estimate RO desalination water production based on the quantity of RO modules sold globally by the RO module manufacturers. This provides an obvious advantage as there are much less RO module manufacturers than the RO module users (water treatment plants). Using this approach and the most recently available RO module sales data, the global water production of RO desalination in 2017 is 122.0 ± 31.5 million m³/d (mean ± SD, at the 95% confidence interval), which is 53.2 million m³/d higher than that of the International Desalination Association estimate (compared by the mean).