Distilled water is tap water that is processed to remove almost all sodium and minerals in the water. Consequently, it has almost no taste.
To make it, water is boiled. The steam is collected, and allowed to condense back into water. The steam leaves everything else behind. Even helpful minerals such as calcium are removed. The process can also be done commercially through a distiller, a reverse osmosis unit, or via de-ionization. You can buy home water distillers.
Distilled water is not necessarily sterile water, because the bottling process may not have been one that standards agencies would consider sterile.
Distilled water can be useful in appliances such as steam irons for clothing, and humidifiers, as using it helps prevent mineral build-up in them, thus extending their lifespan. Some people advise that while using distilled water might mean you don’t have to clean out your drip coffee maker as often to get rid of mineral deposits, others say it will result in very inferior tasting coffee.
Distilled water is very “soft” because of the absence of minerals. Because it’s mineral free, it very readily and aggressively absorbs other minerals that it comes into contact with. For this reason, cooking vegetables in distilled water is not recommended, because the water leaches the minerals out of them.
Do not cook with distilled water in aluminum pots.
Distilled Water’s most useful purpose in the kitchen may be in washing produce, according to the University of Maine’s Food Science and Human Nutrition Department. See the entry on “Wash” for a more detailed discussion.
Many feel that distilled water is less healthy for you, because the body more easily absorbs the minerals dissolved in water than it does minerals in food. Some also feel that drinking it for sustained periods of time will essentially leach minerals such as calcium, magnesium, potassium and sodium from your body, and that making up for it by taking mineral supplements doesn’t seem to fully compensate.
Sometimes water may be double-distilled for use in laboratories.
If you are distilling water yourself for drinking purposes, store it in a clean, covered container or bottle in the refrigerator. Discard after 3 days.