Why Does Bottled Water Taste Better?
It’s all due to minerals and other compounds that the water picks up on its journey. For comparison, water that’s been distilled to remove anything dissolved in it—the water you use in your steam iron—tastes “totally boring, like nothing, dry in your mouth,” . But, as it flows through the ground, through rivers and pipes and so forth, water naturally picks up a variety of soluble ingredients that subtly contribute to its flavour.
Water’s flavour depends on where the water comes from. If you get water from a well, it might have a slightly mineral or chalky taste because it’s passed through layers of limestone deep underground.
Water near the beach often has a slight scent of sulphur because of sulphur-producing microbes in groundwater. The stuff purified from some rivers or lakes can have an earthy, organic taste to it that results from leftover bits of decomposing plant matter. Water bottled from mountain springs, like that from wells, can be packed with minerals that alter its flavour. Calcium makes water taste milky and smooth, magnesium can be bitter, and sodium makes it taste salty.
A highly metallic taste to the water can mean that there are high levels of iron in the water, often leached from old pipes. While that isn’t harmful itself, lots of iron can sometimes indicate the presence of another toxic metal: lead. A medicinal taste is also something to be wary of; sometimes, disinfecting agents react with compounds already in the water to create disinfection byproducts (DBPs). There might not be much in the water, but even a little can greatly affect the water’s taste. Because scientists can’t identify most of these DBPs there’s no telling exactly which DBPs are in medicinal-tasting water, or what their long-term health effects might be.
Water that has an excess of dissolved calcium and magnesium is known as hard water, and its chemistry presents some unique problems for cooks. When it’s used for cooking vegetables or fruits, the minerals can tighten up the plants’ natural pectin, giving rise to phenomena like beans failing to soften no matter how long they’re soaked and boiled. Adding table salt to the water can minimize that toughening. Water that’s too soft, on the other hand, is a headache for bakers, since a certain amount of calcium is needed to help gluten molecules in dough link up.
Other conditions can affect how water tastes as well. In the summertime, more plant matter falls into rivers, giving water more of that earthy taste; seasonal algal blooms can release a stinky (but non-toxic) chemical called geosmin into water that treatment can’t get out. Water that’s drunk too cold will lack most of its flavour. Filters might remove some less desirable flavour elements from water, but they also take out the good parts that make water flavourful and distinctive.
h./t to cooksscience.com for the great article!