Myth: If you’re thirsty, you’re already dehydrated

Actually, your thirst sensations are a pretty sensitive gauge of your fluid levels. “Dehydration is the body’s natural loss of water through sweat, tears and breathing. The kidneys control the water balance in the body, and when they sense the need for more water replacement, it sends a message to our brains to drink more water by making us feel thirsty,” explains kidney specialist Dr Dara Huang.
By the way, make sure you’re not always thirsty for these reasons.
Myth: Drink eight glasses of water every day

No question that drinking enough water is important. But the eight glasses advice is a myth, says Dr Huang, and it can be dangerous. “If your heart or kidneys is compromised, drinking too much water can cause congestive heart failure, pulmonary edema, or water intoxication. In these cases, fluid intake should be limited,” she explains.
To figure out the magic millilitre-count of aqua that your body needs, you should take many factors into consideration, according to nutritionist Dr Roger E. Adams. “This number may be too much for some and not even close for others, especially if you are a heavy sweater, or simply larger. The larger you are, the more water you need for every function in your body, not to mention replacing sweat. However, if you are smaller or don’t sweat a lot, even less than eight glasses may suffice to maintain water balance,” he notes.
When in doubt, talk to your doctor for their expert opinion.
Myth: Always drink water first thing in the AM

You’ve heard it before: “Start your day with a full glass of water.” While you might be thirsty and you might naturally reach for that, Dr Huang says it’s not necessary. “If you have normally functioning kidneys, it may be refreshing to reach for water, but it’s not vital,” she notes. “Some people think that if you go to sleep at midnight and wake up at 8am, you’ve gone at least eight hours without hydrating, so you have to drink water. This isn’t the case. And your urine can give a glimpse too: Your urine is clear because it’s diluted. If your urine is dark, it’s because your kidneys are doing their job to conserve water and it’s concentrated. The first void of the day is usually the darkest,” she notes.
Is it bad to drink water that’s been sitting overnight – or longer?