Nephrologist explains how much water is enough for your kidneys, debunking 4 common myths

Check out if your water limit is adequate or excessive, and how it may impact your health.

Water is regularly touted as the baseline solution for almost everything. You may have heard people treat it as the go-to natural fix for all problems. Getting acne? Drink more water. Not losing weight? Drink more water. Tummy ache? Drink water. While water undoubtedly has its merits, how much is really enough for your kidneys?

We have asked Dr Udit Gupta, consultant- nephrology, ISIC Multispeciality Hospital, who provided a more realistic perspective on water being portrayed as a cure-all, and explained why the ‘drink more water’ advice is actually more nuanced and has more to the story. For your well-being, understanding how much you truly need to hydrate is crucial. Otherwise, you may end up overhydrating, which is not good for your health either. By debunking some common myths you may have heard daily, he clarified the real water requirement. Instead of blindly chugging water, let's take a look at what the healthy approach to hydration is.

Debunking common water-related myths

Water requirement is not universal.

Myth 1: Everyone needs exactly 8 glasses of water a day

The nephrologist said it is not universal, and hydration needs actually differ on many variables, including body weight, climate, activity levels, and overall health status.

Here's why hydration needs differ, as per Dr Gupta, “A child playing outdoor sports in summer will need more fluids than a sedentary adult working in an air-conditioned office. Similarly, people who consume water-rich foods like fruits and vegetables may require less direct water intake.”

He further added, “For kidney health, what matters most is consistent hydration that supports normal urine output, typically around 1.5 to 2 litres per day in adults, adjusted for children by size and age.”This suggests that instead of being focused on the number of glasses, you should drink so that your body can produce a healthy amount of urine that filters out all the toxins from the body.

It is a major shift in focus, from ‘How many glasses did I drink?’ to ‘Is my body hydrated enough to produce normal, healthy levels of urine?’

Myth 2: More water is always better for the kidneys

This narrative is one of the key drivers of the ‘drink more water’ discourse. Since water is believed to flush toxins out of the blood through urine, many assume it will, by default, also improve function, with the more is merrier logic, and reduce the risk of kidney stones and urinary tract infections in vulnerable people.

But this is not always the case. Overhydration is a serious condition that can, in fact, can be detrimental to your renal health.

Describing the problems that overhydration may cause, Dr Gupta explained, warning that excessive water intake is not always helpful, “Overhydration can dilute sodium levels in the blood, a condition known as hyponatremia, which can be dangerous. For most healthy individuals, drinking beyond thirst does not ‘supercharge’ kidney function. The kidneys work efficiently within a wide range of fluid intake.”

Myth 3: Clear urine means perfect hydration

Urine colour is thought to be the signal that you are properly hydrated, but the colour, as per the nephrologist, shou;d not always have to be colourless. In some cases, he warned, it can mean overhydration. Instead, pale yellow urine actually shows adequate hydration. But dark yellow and amber urine mean dehydration, and Dr Gupta warned one should increase fluid intake.

Myth 4: You only need water when you feel thirsty

The thirst response, which usually presents as dryness in the throat or the urge to drink water, usually signals that you are already mildly dehydrated. However, the nephrologist cautioned that certain groups, including young children and older adults, may not recognise third cues effectively.

He added that athletes, people with fever, who are vomiting or suffering from diarrhoea and those living in hot climates should actively maintain hydration instead of relying on thirst cues alone.

How much water do kidneys really need?

The nephrologist answered that most adults require about 2–3 litres of total fluids daily, including water from food and beverages, while a child's needs will depend on their age and body size. But caution should be exercised by people with certain medical issues. Dr Gupta named: People with kidney disease, heart conditions, or specific medical issues. They should follow medical advice, and sometimes fluid restrictions are advised. “Your kidneys are designed to work efficiently; all they ask is that you give them enough, not excess,” the nephrologist added.

Note to readers: This article is for informational purposes only and not a substitute for professional medical advice. Always seek the advice of your doctor with any questions about a medical condition.