The primary difference between distilled water and spring water is the purification process, though there may also be differences when it comes to where the water comes from or how it is processed. In general, spring water has been pumped from a natural spring, and usually contains a number of minerals. Manufactures filter it for impurities like dirt and bacteria, but typically leave the minerals and other naturally occurring elements in to improve the overall taste. Distilled water, on the other hand, is boiled for so long that the water molecules become vapor, essentially shedding both impurities and minerals. The result is a very pure product that contains basically nothing but hydrogen and oxygen.
People can typically drink both versions, though distilled water is not usually designed for hydration. While spring water is often marketed as a natural way to hydrate the body, distilled versions are more commonly used in settings that requite ultra-pure water, like heavy industry or scientific labs. It may also be recommended for use in household appliances since the lack of minerals means there won’t usually be any buildup over time.
One of the first things to think about when discussing distilled water and spring water is where each comes from. Spring water originates in natural “springs,” which are fresh water pools and streams that come from underground aquifers and are present in varying sizes in most parts of the world. Some springs are more renowned than others for their drinking water, and the mineral content can vary dramatically from place to place. Many manufacturers try to boost the sales of their products by focusing on the unique benefits or contents of the springs they come from.
Distilled water might come from a spring, but it could just as easily come from a river, a reservoir, or even the ocean. Where distillation is concerned, the process is much more important than the source.
Distillation Versus Filtration
It is sometimes safe to drink water directly from nature, though most countries have laws requiring purification before it is sold to consumers. There are a couple of different ways to purify water, but the main goal is to remove debris, bacteria, and chemicals that may be present. Distillation is a very rigorous way of purifying water, and leaves very little room for error.
During distillation, water is purified through a “super-heating” process that essentially brings the water to boiling, causes the molecules to turn to vapor, then reclaims that vapor and forces it back into a liquid state in a sterile environment. When the vapor forms, the water molecules lose all of their prior contents, be they harmful toxin or helpful mineral. The result is something that is exceptionally pure and contains virtually nothing but bare hydrogen and oxygen molecules.
Spring water, on the other hand, is usually purified using advanced filtration. Once pumped from the springs, the water is forced through fine-grade filters that catch impurities on the molecular level. In most cases these are designed only to remove things that are known to be bad, like toxins or pollutants. Naturally occurring minerals typically remain.
Distilled water is very important to many different industries, particularly those that depend on heavy or precise machinery. Washing these tools with ordinary water can lead to mineral buildup over time; things like calcium and magnesium are known to leave deposits on certain metals which can corrode surfaces and reduce the efficiency of moving parts. Scientific labs are another big distilled water consumer. Using only completely pure water in experiments and to clean equipment like test tubes can be a good way to help prevent contamination or results that are skewed by the presence of certain minerals.
Some home appliances may also work better, or at least more efficiently, with water that has been distilled. Irons and steam cleaners are good examples. Almost anything with small crevices that are exposed to heat can get gummed up if they are used with water that has things like calcium in it. Using distilled water isn’t a guaranteed way to improve appliance performance, but it can sometimes prolong lifespan.
Spring water, by contrast, is almost always marketed as a hydration beverage. People may also use it to care for plants and shrubbery, as the minerals it contains are often thought to be somewhat helpful to things like flowers and trees, particularly in areas where the soil doesn’t contain many natural nutrients.
Differences in Taste
Distilled water can be and sometimes is consumed for hydration, but it usually has a very different taste from spring water. This is typically true even if the waters come from the same place. Many people find that the distillation process leaves water tasting very astringent, and it can be less satisfying when thirsty because it tends to draw essential minerals out of the body's tissues in order to restore the electrolyte balance.
Spring water tends to have a "wetter" mouthfeel. Its taste is in many ways influenced by the precise mineral composition of the spring it came from, but it is usually described as somewhat rich and complex.
There is some controversy when it comes to the wisdom of drinking distilled water with any regularity. Some dieters drink it on the belief that it will regulate the body's cell functions, though whether or not this is true is open for some debate. Some scholars say that distilled water can help restore a more alkaline blood chemistry, but a roughly equal number suggest that regular consumption can be unnecessarily taxing on the body, as blood cells are not designed to absorb “pure” water and may actually depend on naturally occurring minerals and salts to properly absorb things.
Of course, there are situations where distilled water is the best choice. People who live in regions where there is no safe drinking water are often better off choosing distilled over something that is possibly contaminated, for instance; those who spend long stretches at sea, like commercial fishermen, may also use distillation as a way to make saltwater drinkable. Most health experts don’t recommend that people choose distilled water as their primary source of hydration, but it is usually safe for consumption in small doses. The biggest exception is water that has been stored in contaminated containers. Just because the water starts out completely pure doesn’t mean it will reach the consumer that way, particularly if the distillation happened in a place where there are a lot of impurities, like a chemical plant.