Desalinated seawater is the main source of water for the GCC. Portable Water Treatment Plants are used to purify water for drinking purposes from untreated sources of water such as rivers, seas, lakes, and wells. Their main function is to eliminate pathogens, suspended solids, and unpalatable or toxic compounds. Techniques include heat (such as boiling), filtration, activated charcoal adsorption, chemical disinfection (e.g. chlorination, iodine, ozonation, etc.), ultraviolet purification (including SODIS), distillation (including solar distillation), and flocculation. Often these are used in combination.

Chlorine or Sodium Hypochlorite are mainly used for water chlorination in Portable Water Treatment Plants. These chemicals are used to kill certain bacteria and other microbes in water, as chlorine is highly toxic.

In particular, chlorination is used to prevent the spread of waterborne diseases such as cholera, dysentery, and typhoid. Caustic Soda also is used to regulate the pH levels of water.