The eight glasses of water per day myth has been debunked over and over again – yet it refuses to die. Where did it come from? And why isn’t it going away?

Let’s travel back in time, to 1829, when Vincent Priessnitz opened the first ‘hydropathy’ clinic in Austria. He believed that water could cure any ailment, and he had his patients undergo waterfall therapy, sitz baths (where you sit in warm, shallow water to relieve pain in your bottom and genitals), and to drink somewhere around 1.5 L of water per day to cleanse one’s system. Even Charles Darwin undertook the Water Cure, where he sat under a cascade of cold water in an attempt to cure an unknown illness.

Jump forward to 1945, when the US Food and Drug Administration added a footnote to its Dietary Guidelines. They suggested that “2500 mL of fluid should be ingested on a daily basis”, because the average male would consume 2500 kcal (what we think of calories), and apparently each calorie would ‘require’ 1 mL of water to, I dunno, do something. They never said what. They didn’t cite any studies to back up the claim.

Fast forward to 1967. Dr. Irwin Maxwell Stillman created the ‘Stillman Diet’, which was then advertised in the book The Doctor’s Quick Weight Loss Diet, which was co-authored by self-help writer Samm Sinclair Baker. (Is it just me or does that sound like the kind of book that would reach the top of the New York Times Bestsellers in 2021?) The Stillman Diet was essentially a low-carb diet, where one ate meat, fish, eggs, cottage cheese, tabasco sauce, herbs and spices, and… well, that’s about it. Oh, and you could have tea, coffee and non-caloric soft drinks, but you also had to have eight glasses of water every day. Dr. Stillman claimed that you needed eight glasses of water per day to ‘wash away’ the fatty acids that resulted from fat breakdown in the body. Why exactly this was needed he admitted was “not fully understood”.

Then enter Fredrick J. Stare – an American nutritionist at Department of Nutrition at the Harvard School of Public Health – who in 1976 co-authored a book where he claimed the eight glasses was true but it was for all fluid, including tea, coffee, soft drink, beer, and the water in fruits and vegetables.

I don’t want to disregard any of the good things he did, but he got a lot of funding from the food industry. He defended the processed American diet, thought sugar was all good, and claimed that Coca-Cola was “a healthy between-meals snack”.

So if all this eight glasses stuff is just crap pushed by diet gurus back in the day and repeated over and over again, why does it still pervade society in 2021? There’s no question that water is good for you, but look close enough and you’ll find, surprise surprise, bottled water companies. In 2011, Glasgow GP Dr. Margaret McCartney published a paper about Hydration for Health – a initiative that promotes drinking a whole lot of water. But the initiative and it’s annual scientific conference were created and are sponsored by Danone – the French food giant behind Volvic, Evian, and Badoit bottled waters.

Enough of my ramblings now, let me sum up. You don’t need to drink eight glasses of water per day. Or fluid. There’s no scientific basis to back up that claim in any way. Instead, you can just drink when you’re thirsty. Water is great, and is obviously better than drinking soft drinks, but you don’t need lug a giant drink bottle with you wherever you go and sip on it all day long.