There are two types of evaporation processes commonly used, MSF (multi stage flash) and LT-MED (Low temperature multi effect distillation) while the dominating filtering process is RO (reverse osmosis), the latter can be either BWRO (brackish water RO) or SWRO (seawater RO).

RO is gaining ground at the sacrifice of MSF both in terms of numbers of plants and capacity installed. One obvious reason for this development is the reduced cost for membranes, 50% drop during the last ten years. Another future concern, increasing the RO share even more, might be the release of exhaust gas from the huge distillation plants where energy is achieved by combustion of fossil fuels, oil and gas.
Also different types of MED-plants are increasing in number, probably due to less maintenance problems connected with calcareous deposits when compared to the MSF-plants.