There is disclosed a steam plant 10 comprising a processing unit 12 arranged to treat raw water; a boiler 18 arranged to generate steam; a blowdown vessel 20 in fluid communication with the boiler so as to receive hot blowdown water from the boiler; and a reverse osmosis unit 14. The reverse osmosis unit 14 is in fluid communication with the processing unit 12 though an inflow water line 24, the boiler 18 through a permeate line 60, and the processing unit 12 and/or the blowdown vessel 20 through a concentrate line 74, 76, 78, 80, 82. In use, the reverse osmosis unit 14 receives treated inflow water from the processing unit 12 and generates permeate which is provided to the boiler 18 through the permeate line 60 and concentrate which is provided to the processing unit 12 and/or the blowdown vessel 20 through a concentrate line 74, 76, 78, 80, 82. There is also disclosed a method of operating a steam plant and a method of upgrading an existing steam plant.