In the last two decades there has been a small but steady replacement of ageing MSF type desalination units installed at Japanese power plants with either MED or RO desalination plants. These have proven to be very competitive and reliable technologies, and the operating experience especially with MED type plants has been very encouraging. The use of desalinated water for Japanese power plants gives the customer significant advantages especially in a land as environmentally conscious as Japan. It is anticipated that the replacement market will continue at the current level and that additional new power plant projects will give increasing consideration to the use of desalination technologies to meet their needs for high quality, and reliable availability, water requirements.