Ellen Says:- Distilled water is often defined as bottled water that has been produced by a process of distillation and has an electrical conductivity of not more than 10 µS/cm and total dissolved solids of less than 10 mg/L.
Distillation involves boiling the water and then condensing the steam into a clean container, leaving most solid contaminants behind. Distillation produces very pure water but also leaves behind a white or yellowish mineral scale on the distillation apparatus, which requires that the apparatus be frequently cleaned.
Distillation does not guarantee the absence of bacteria in drinking water; unless the reservoir and/or bottle are sterilized before being filled, and once the bottle has been opened, there is a risk of presence of bacteria.
For many applications, cheaper alternatives such as deionized water are used in place of distilled water.