A simple, cost effective method of producing 10-1µS.cm purified water at low volumes. The Labwater units incorporate an easily replaceable cartridge, containing specifically designed resin, which changes colour through absorption of ionic contaminants, facilitating a low level of maintenance. On colour change from blue to brown, replace the cartridge. The units are typically wall mounted and are easily connected via a dedicated hose (supplied separately) to a tap or stopcock and operate direct from water pressure thus requiring no external electrical supply.