Humans can taste water — the tongue has receptors specifically for it
For years it was believed water had no taste because it lacks the chemicals that trigger taste receptors. A 2017 study showed that sour-sensitive cells in the tongue also respond to water — the acid-sensing ion channels fire when water is present, particularly after tasting sour or salty foods. This creates the perception of 'water taste'. The researchers also found that this pathway links to the brain's thirst regulation system, suggesting taste of water may help calibrate how much to drink.
Water is commonly defined as tasteless — it's even used as the reference point ('this tastes like water') for absence of flavour. Finding that the tongue has a specific mechanism to detect water reframes one of the most fundamental things we consume.
“Humans can taste water. The tongue has sour-sensitive cells that also fire in response to water — a mechanism linked to the brain's thirst regulation system. Water is not tasteless. 💧 #OddlyHuman”