The differences between distilled water and tap water go beyond the fact that tap water comes from home faucets and distilled water comes from a bottle. The major difference between these two types of water is that the purity and content of tap water is regulated by the government and distilled water is not. Distilled water remains consistent no matter where it is purchased; however, what's in tap water varies from place to place.
The U.S. Environmental Protection Agency regulates the nation’s tap water quality, whereas distilled water is not regulated by the EPA. This government agency monitors the amount of pollutants and other substances found in local drinking water to make sure that they follow government standards. EPA regulations ensure that water is safe for human consumption.
Tap Water Purity
The University of Illinois department of physics says that the difference between distilled water and tap water is that tap water does not go through the same purification process as distilled water. Tap water, which is not highly purified, can contain trace amounts of substances like salts, nitrates, chloramines, fluoride, and microorganisms, as long as the amounts meet EPA regulations.
Distilled Water Purity
Distilled water comes from recondensed steam. The purification process includes boiling water and collecting water vapors that return to its liquid state. This process causes impurities to separate for the distilled water, leaving water in its purest form.
The difference between distilled water and tap water is that the water composition of distilled water is consistent because it goes through the same distillation process. Although all tap water in the United States must meet EPA standards, composition varies depending on location and how the local treatment plant filters the water. The composition further changes if people have filtration devises at home.
The University of Illinois department of physics states that there are visible differences between distilled water and tap water. For instance, ice cubes made from tap water are not clear and contain lots of air bubbles. Ice cubes made from distilled water are more transparent.
Industrial and Household Uses
Multiple industries use distilled water more than tap water because of distilled water's purity. These industries include beverage manufacturers and car fluid producers. People often use distilled water instead of tap water in their home aquariums and in appliances such as steam irons and humidifiers.