The taste and even nutritional benefits of water boil down to its mineral content.

“For many people, water should have a neutral taste. This is usually the case with low-mineralized mineral water, purified water, or tap water,” said Timo Bausch, a water sommelier based in Germany and the founder of SOMMcademy, a water-tasting company.

Distilled, purified, or tap waters are typically heavily filtered and processed to make them safe to drink. The processes vary, but it normally entails removing dangerous contaminants like bacteria, chemicals, and toxins from water collected from various sources. Unfortunately, that can also filter out the naturally-occurring minerals that give water its taste and health benefits. Sometimes, minerals are added back into processed water to make it more palatable.

By contrast, water that is bottled at the source (often called “mineral” or “natural” water) is tested and certified to be safe to drink without processing, so it naturally contains minerals like calcium, magnesium, potassium, iron, and zinc. These minerals could provide important health benefits like lowering blood pressure, improving blood circulation, strengthening bones, and promoting digestion.

Water that tastes bland or leaves your mouth feeling dry could be low in minerals that are good for you, but water that has a high concentration of minerals could be difficult to find, expensive to buy, or too tasty to drink all the time. That’s why the question of which water is best comes down to, well, taste and preference. While that’s not something many people pay attention to, Binder said that all it takes is one water-tasting experience to never look at water the same way again. It’s just a matter of realizing that water can taste and feel different.