All water is the same, right? Not so fast! If you have ever looked at the fine print on a bottle of water, you know there are many different kinds of water – there is spring water, distilled water, and some water is purified with reverse osmosis. But does anyone know what makes spring water different from filtered water, or why distilled water is rarely sold for drinking? Read on to learn the differences between the most common types of purified water.
Filtered water is, unsurprisingly, water that has been filtered. Filtration is the most basic way of making sure water is safe to drink. During the filtration process, water is passed through a series of increasingly selective filters that pull different impurities out of the water. Filtration may use a combination of filters for different impurities. For example, a carbon filter might be used to neutralize chlorine, while other filters might have tiny pores (as small as one micron!) to remove other contaminants. Filtration is the most common way to purify water because it is effective and relatively inexpensive.
Distilled water is water which has gone through the process of distillation. During the distillation process, ordinary water is heated so that it transforms into vapor. Impurities like bacteria and other contaminants are too heavy to stay in the water as it evaporates, and are left behind. The purified vapor is then condensed back into liquid water, and bottled into individual bottles or jugs. Distilled water does not have any mineral content, so it is not often used for drinking (it tends to taste really bad). Instead, it is used scientifically, where any impurities in water could affect the results of an experiment.
Spring water is water which rises to the surface from underground reservoirs. This water is then collected and can be packaged into bottles. Spring water is naturally filtered as it passes through layers of rock. The movement of spring water through rocks means that it often has lots of dissolved minerals, which lends it a distinct taste. Minerals in spring water aren’t just for taste, though. Many minerals found in spring water are necessary for a variety of chemical reactions in the human body, and drinking spring water ensures that your body gets healthy levels of these trace minerals.
Another common way of purifying water is through a process called reverse osmosis. What is reverse osmosis? It’s a complicated-sounding name for a simple process. Reverse osmosis takes regular tap water and uses pressure to force it through a filter. The filter has pores which traps contaminants, including dirt and other molecules which should not be in the water. Only water is allowed to pass through. The result of the reverse osmosis process is purified water. Although the small pores in the filter are good at filtering out large molecular structures like salt, small molecules can still pass through. Examples of dangerous small particles include pesticides, herbicides, and chlorine. For this reason, reverse osmosis is often combined with other filtration techniques to create the best drinking water possible.
Because each water purification technique has different advantages and disadvantages, they are often combined to create the best drinking water possible.