Nephrologist reveals if you should have 8 glasses of water everyday, busts other hydration myths

It is important to know the difference between healthy hydration and excessive intake of water. (Picture: Pexels)

• Hydration needs vary by age, activity, climate, and health status
• Thirst is a reliable signal for most healthy adults
• Overhydration can cause health risks like hyponatremia

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There’s plenty of hydration advice out there, but it’s not all true. Knowing how the body manages fluids, noting signs of thirst and not drinking too much are all key. Experts say you should focus on personalized hydration habits rather than strict or popular rules about how much water to drink.

Hydration is often one of the simplest pillars of good health but is riddled with misinformation. From the frequently cited “eight glasses a day” guideline to the idea that perfectly clear urine always indicates ideal hydration, many people stick to inflexible routines without considering their body’s actual needs. Social media trends and advice around wellness have popularised the notion that simply drinking more water guarantees better health outcomes.

But the human body manages fluid balance in a much more advanced fashion. And things like climate, physical activity, diet, age and health conditions all affect how much water a person needs. Overhydration, like dehydration, can sometimes pose health risks — specifically for people with kidney or heart disease. That’s why it is important to know the difference between healthy hydration and excessive intake.

Also read: 38-year-old physician reverses fatty liver, high bp, high cholesterol, type 2 diabetes, drops 56 kilos in 18 months

Although the general advice is to remind oneself to stay hydrated, it should be steered by the feeding of your body signals and the health status as no specific rules apply in every case, says Dr Sheel Bhadra Jain — Senior Consultant – Nephrology & Renal Transplant, CK Birla Hospitals, Jaipur.

The eight glasses rule was never medical advice

The origins of the eight-glasses-a-day recommendation are murky at best. No major clinical body, not the WHO, not the Indian Council of Medical Research, has ever issued this as a universal guideline. Fluid needs vary considerably based on body weight, climate, physical activity, diet, and health status, says the doctor.

“A sedentary office worker in an air-conditioned building in Mumbai has different requirements from a construction worker in Nagpur in May. Treating them identically is not medical thinking,” says Jain.

What most people also underestimate is how much fluid comes from food. Fruits like watermelon, oranges, and cucumber contribute meaningfully to daily intake and so does dal, buttermilk, coconut water, and even tea and coffee, despite the persistent myth that caffeine negates hydration entirely. The kidneys are remarkably efficient at managing what comes in, regardless of the source.

“Lastly, thirst has been unfairly maligned. The popular claim that feeling thirsty means you are already dehydrated is not accurate for most healthy adults,” says the doctor.

In clinical practice, according to the doctor, the groups for whom thirst becomes a less reliable guide are the elderly and those with specific medical conditions, not the general population scrolling wellness content at midnight.

When more water becomes a problem

The kidneys filter approximately 180 litres of blood daily, but they can only excrete about one litre of water per hour. Consistently drinking beyond what the body needs dilutes sodium in the blood, a condition called hyponatremia. In mild forms, it causes fatigue and confusion. In severe cases, it can be life-threatening.

What To Keep In Mind

Completely clear urine, which many people chase as a hydration goal, is actually a signal of excess, not optimal function. Pale yellow is what adequate hydration looks like. Dark amber warrants attention, though even that requires context as certain vitamins, medications, and foods like beetroot can alter urine colour independent of fluid status.

For most healthy adults, the guidance is straightforward. Drink when thirsty, eat a diet that includes water-rich foods, and pay attention to context as heat, exercise, illness, and travel all shift requirements.

Also read: Doctor says these 3 medicines can save a heart attack patient

Patients with kidney disease, heart failure, or liver conditions need individualized guidance, because the standard advice does not apply and can cause harm.

FAQs on myths around hydration

1. Do you really need to drink 8 glasses of water daily?

Not necessarily. Hydration needs vary based on age, activity level, climate, and diet.

2. Is thirst a bad indicator of dehydration?

No, thirst is your body’s natural signal. However, waiting too long may mean you’re already mildly dehydrated.

3. Does drinking more water always improve skin?

Water helps overall health, but it’s not a magic fix for glowing skin—diet and skincare matter too.

4. Can you drink too much water?

Yes, overhydration can lead to Hyponatremia, a condition where sodium levels in the blood become dangerously low.

5. Are all fluids equally hydrating?

Most fluids contribute to hydration, including milk, soups, and herbal teas—not just plain water.

Disclaimer: This article, including health and fitness advice, only provides generic information. Don’t treat it as a substitute for qualified medical opinion. Always consult a specialist for specific health diagnosis.