According to All About Water, “water filters provide the best and healthiest solution to the problems of both bottled water and tap water.” While filtered water is the best choice for drinking, distilled water contains no minerals and is best used for industrial or scientific purposes.
Water is purified when passed through filters that trap contaminants, absorb harmful chemicals, remove chlorine and chlorine byproducts and filter out volatile organic chemicals (VOCs). According to the Natural Resources Defense Council, "household water filters generally fall into one of two categories: point-of-entry units, which treat water before it gets distributed throughout the house; and point-of-use units, which include countertop filters, faucet filters and under-the-sink units."
The contaminants -- or heavy metals -- in regular tap water are separated from water molecules using extreme heat until it evaporates, is stripped of its minerals and processed back into liquid form through steam. Distilled water is used mostly in laboratories or in the printing business.
“Water filters are able to remove far more contaminants than any other purification method,” according to All About Water's website. Filtered water is economical and minimal water is wasted during the purification process. Activated carbon filters, such as those used on countertops and attached to faucets, remove odors and give tap water a better taste. Distilled water is often consumed by people in developed areas where contaminated drinking water would cause illness.
The distillation process does not remove chlorine or other VOCs found in municipal drinking water. Distilled water is highly acidic and mineral-free, making it unhealthy for people to drink.
The filtration process that uses granular filters doesn't absorb harmful chemicals and the process that uses rapid water filters moves water through too quickly and doesn't trap all contaminants.