What is the difference between RO and DI water?
The technique used to remove the impurities/ions. RO uses a semi-permeable membrane which is fine enough so that essentially only water molecules will pass through it. As a result you produce about 3 times as much waste water as purified water. DI uses ion exchange resins, which exchange the ions in the water, such as iron, magnesium, copper for hydrogen and nitrate, sulphate, phosphate for hydroxide.