Water is our simplest nutrient. It requires no more preparation than turning on a tap. We know when we need to drink it because we feel thirsty. Fully functioning adults tend not to forget to drink enough water to survive.

Yet companies old and new want to convince us that humanity has a drinking problem. New “smart cups” from Thermos and San Francisco-based start-up Mark One use an array of sensors that beam users’ real-time data about water consumption to a smartphone app. But does such a simple act as drinking really need all this tech?

Being well hydrated can make us feel more alert and focused, as well as boosting our immune system. The apocryphal advice of eight glasses of water a day is actually a little less than the 2.7 litres recommended for women and 3.7l for men by the US Institute of Medicine. But, as the institute concluded: “The vast majority of healthy people adequately meet their daily hydration needs by letting thirst be their guide.”