When Did We Start Carrying a Litre of Water Around?
We are in one of those extraordinary British hot spells as the Met Office has reported temperatures pushing into the high 30s in parts of England this week, and 2026 is currently on course to be the UK’s warmest summer on record.
So yes, drink more if you’re hot. Obviously.
But here’s the thing.
When I was growing up in the 1960s and 70s, we didn’t spend our days drinking water. We didn’t have ‘hydration goals’.
We simply drank something when we needed a drink.
There were no enormous, insulated bottles sitting beside us on the desk. Nobody wandered around with a water bottle clipped to their handbag. We didn’t have hydration apps reminding us that we were 37% behind our daily target. And nobody told us that if we waited until we were thirsty, we had already made a terrible physiological error.
We drank when we were thirsty.
We had tea. Lots of tea. Milk. Squash. Soup. We ate fruit and vegetables. We had meals. And occasionally, if we were outside on a hot day, somebody would say, “You’re thirsty — have a drink.”
It all seemed remarkably straightforward.
So, when did water become an obsession?
The history of the modern ‘drink eight glasses of water a day’ message is surprisingly interesting.
In 1945, the US Food and Nutrition Board1 suggested that adults required approximately 2.5 litres of water a day. Crucially, however, this referred to total water intake, and the recommendation explicitly stated that “most of this quantity is contained in prepared foods”.
In other words, the recommendation was about total water intake, not about drinking 2.5 litres of plain water. The distinction seems to have been rather spectacularly lost somewhere along the way. If you ate 2,000 calories, the calculation produced roughly 2 litres of water. Turn that into eight 8-ounce glasses and, hey presto, we have the famous 8 × 8 rule.
In 2002, physiologist Heinz Valtin2 went looking for the scientific evidence behind the ubiquitous modern advice to drink eight glasses of water a day.
He couldn’t find it.
His review concluded that there were no scientific studies supporting the specific 8 × 8 recommendation for healthy adults living in temperate conditions. He also pointed out that the body has a remarkably effective system for regulating water balance; including that rather useful sensation we call thirst.
This is rather awkward for an instruction that has become so embedded in modern wellness culture. Because once something gets repeated often enough, it acquires an air of scientific authority all by itself.
And then water became a ‘wellness product’….
Somewhere between the 1980s and today, hydration stopped being something your body quietly regulated and became something we were apparently expected to manage ourselves with military precision.
We began buying bottled water.
Then came sports drinks.
Then enormous reusable bottles.
Then motivational bottles with markings saying things such as 7am: Let’s Do This! and 9am: You’re Amazing!.
In genuinely hot weather, during vigorous exercise, heavy physical work, fever, vomiting or diarrhoea, fluid requirements can increase substantially. The 1945 recommendation itself recognised that circumstances such as heat and hard work alter requirements.
But that is very different from telling every healthy person that they must force down several litres every day regardless of thirst, diet, weather or activity.
Perhaps the strangest part of the modern hydration obsession is that we’ve somehow come to distrust one of the body’s most basic regulatory mechanisms. Thirst exists for a reason. Your body detects changes in fluid balance and prompts you to drink. You drink. Your kidneys adjust what happens next. It’s not a perfect system in every circumstance, of course. Older people can have a reduced sensation of thirst, and illness, medication, extreme heat and prolonged exercise can all change the equation.
But there is such a thing as drinking too much. Excessive water intake can dilute blood sodium and, in extreme cases, cause potentially dangerous hyponatraemia.
So perhaps the question isn’t:
“Have I drunk enough water today?”
Perhaps it is:
“Am I thirsty?”
Perhaps we could stop pretending that every healthy adult needs to spend the day permanently attached to a water bottle. The whole idea of water as a wellness behaviour seems to have developed in stages, with the big cultural shift occurring from the late 1970s through the 1990s. Water was beginning to be marketed as a lifestyle choice rather than merely something that came from the tap.
Perrier is interesting. Its US sales increased from around 3 million bottles in 1975 to about 200 million by 1979 because it wasn’t simply selling water: it was selling an image of sophistication, health and an alcohol-free alternative. The underlying message was remarkably simple:
More water = healthier you.
And once that ‘fact’ entered into the public consciousness and developed into a lifestyle choice then major drinks companies entered the market, and water as a product increasingly appeared in gyms, offices, and supermarkets in plastic bottles that it was somehow better for you to buy that turn the tap on.
I don’t know. Maybe I am just getting old and cynical. But I still prefer to brew a nettle tea or turn on my tap when I am thirsty instead buying of a calibrated plastic bottle telling me how much I have to drink before lunch time…
1Food and Nutrition Board, National Research Council (1945). Recommended Dietary Allowances. Washington, DC: National Research Council.
2Valtin H. (2002). “Drink at least eight glasses of water a day.” Really? Is there scientific evidence for “8 × 8”? American Journal of Physiology—Regulatory, Integrative and Comparative Physiology, 283(5), R993–R1004. DOI: 10.1152/ajpregu.00365.2002.
