Demineralisation (‘Demin’) plant. Boiler feed water and chilled water feed were softened here using salt (an ‘ion exchange’ process I believe). The water is also treated with chemicals to eliminate any bacteria or other impurities. This water is also fed to the print floor as some of the machinery requires demineralised water.
This was at the NE end of the pump area of the Boiler House that ran parallel with the subway between F and B core. The sacks to the right were added to the water to soften it.