Distilled water is created by heating the water until it evaporates, which only affects the water molecules, so residue is left behind. The purified water is cooled until it becomes a liquid and is packaged as distilled water. Because distilled water has been stripped of its minerals, it’s often used in:

• steam irons
• aquariums (mineral supplements should be added to the fish food)
• car cooling systems
• laboratory experiments
• certain medical devices, such as continuous positive airway pressure (CPAP) devices.

CPAP machines should use distilled water which removes nasty contaminants, minerals and pollutants from the water, maintaining a healthy chamber while protecting the patient and equipment.