Distillation is an old and reliable form of water purification that has been around since World War II. This process produces clear and clean water that is almost entirely free of minerals, biological matter, chemicals, and other impurities.
Distilled water is often used for laboratory and industrial purposes that call for high-purity water. Usually, water carries all kinds of impurities, which may cause chemical reactions when it is used as a solvent or in other processes. Distillation is a cheap and reliable way to treat seawater or a water source of unknown or known-bad quality to produce clean water.
However, there are concerns that the lack of minerals and other trace elements in distilled water is harmful to your health. This process, especially super-pure distillation made possible with today's technology, is said to be depriving your body of needed minerals and diluting your electrolyte and enzyme balances over time. (Related: Water is life: 10 Ways to purify water when SHTF.)
Distilled water is highly useful and certainly safe to drink -- at least for short periods. When you're in a survival scenario, however, there is no knowing how long your situation would last. Is distilled water safe for long-term drinking?
Distillation does not remove every particle present in water, but it certainly removes minerals like calcium, magnesium, iron and zinc. While food is the primary source of these minerals, distillation is found to remove up to 60 percent of these minerals from food when using distilled water for cooking. This suggests that long-term use of distilled water for cooking could have harmful effects on vital mineral levels in your body.
In the 1980s, the World Health Organization extensively investigated the effects of demineralized water and found that drinking distilled water will make you pee more. While not a major concern, urination is closely linked to kidney function, and anything that prompts your body to discharge fluids more readily should be noted. Moreover, distillation eliminates electrolytes and dilutes the concentrations of vital serums in the body. These findings come from drinking exclusively distilled water for a long period of time.
On a normal day, your body is consuming minerals constantly, and you lose them when you sweat. Replenishing your mineral levels is vital for cellular membrane health, electrolyte balance, metabolic function, hormone function and even oxygen use. In a survival scenario, however, your body loses minerals faster than you can replenish them, as you try to survive by running, building, even fighting. Unfortunately, rehydrating with distilled water will not replace those minerals.
Adequate levels of minerals and other nutrients are vital to good health. You will need all of your strength and energy to live another day when all hell has broken loose.
In other words: If at all possible, try to avoid the long-term use of distilled water as your primary source for drinking and cooking if you can find other options. The resulting loss of minerals in your body over time may expose you to health risks or exacerbate existing ones.
Sources include:
WHO.int [PDF]