Both methods require relatively high levels of energy to pump water in and out of facilities. Distillation also requires boilers, another energy cost. The process of reverse osmosis, then, turns that natural force against itself so that the water repels salts instead of attracting them. The RO process is relatively straightforward. The result is water well-suited for agricultural and industrial uses and often for drinking water.
Electrical energy is by far the single greatest cost involved in desalination.
Some estimates are in the 55-65 cents per thousand gallon range, not counting waste disposal costs, which in turn can double or triple that number. Maintenance costs for RO generally are limited to the maintenance and repair of electrical motors associated with the process. Current RO filters can be used for up to five years, a marked improvement over the one-year life of RO filters manufactured just five years ago. RO units run unattended so they entail little or no labor expense. Desalination projects around Texas In 1995, the City of El Paso operated a pilot RO project for a six-month trial, with very favorable results.