Dr. Aaron E. Carroll explains — again — why you don’t have to drink eight glasses of water a day. He first wrote about this in a paper in the British Medical Journal in 2007 on medical myths. Two years later he expanded it into a book, again debunking the eight-glasses-a-day myth. Yet it still persists today, despite no evidence to prove its effectiveness.

Many people believe that the source of this myth was a 1945 Food and Nutrition Board recommendation that said people need about 2.5 liters of water a day. But they ignored the sentence that followed closely behind. It read, “Most of this quantity is contained in prepared foods.”

Water is present in fruits and vegetables. It’s in juice, it’s in beer, it’s even in tea and coffee. Before anyone writes me to tell me that coffee is going to dehydrate you, research shows that’s not true either.

Although I recommended water as the best beverage to consume, it’s certainly not your only source of hydration. You don’t have to consume all the water you need through drinks. You also don’t need to worry so much about never feeling thirsty. The human body is finely tuned to signal you to drink long before you are actually dehydrated.

Read Dr. Carroll’s full piece here.