“Drink more water” may be the most common health advice there is. Carry a big bottle, finish three litres a day, flush everything out. It sounds harmless, and for many people it is. But doctors say hydration isn’t a one-size-fits-all target, and for some people, especially those with kidney problems, more water is not always better.
To understand how much water is too much water, what counts towards our daily fluids, how to tell if we are drinking enough, and when our kidneys may need us to go easy on the water.
Why more water isn’t always better
Water is essential for the kidneys to function properly, but more water does not always mean better health. “While staying hydrated is important, people with kidney problems may need to be more careful about how much they drink,” says Dr. Suman Lata, HOD & Consultant - Nephrology and Kidney Transplant, Manipal Hospital, New Delhi.
“In chronic kidney disease (CKD), the kidneys gradually lose their ability to filter waste and remove excess fluid from the body. This can cause fluid to build up and may lead to complications,” Dr. Lata adds.
How much water do you really need?
“The amount of water a person needs depends on factors such as age, activity level, weather, diet and overall health,” Dr. Lata says, adding that the ICMR-NIN dietary guidelines suggest that around 8-10 glasses of water a day, roughly 2-3 litres, may be sufficient depending on individual needs.
“If someone exercises or is outside most of the time during hot weather, this may require the person to drink more fluids, as sweat evaporates from the body,” says Dr (Col) Vijay Dutta, Director, Internal Medicine & Respiratory Services, ISIC Multispeciality Hospital. “Likewise, diarrhea or vomiting can cause loss of fluids,” he says, adding that this is why there cannot be one water target that is suitable for everyone.
It’s not only water that counts
“Also, total fluids received are not only from water but other fluids too,” Dr. Dutta says. “Milk, soups and other liquids help to stay hydrated and both fruits and vegetables including watermelon, oranges and cucumber are relatively high in water,” he explains. “So, it may not be enough to count the glasses of water you drink,” he points out.
Listening to your body
Most healthy individuals will experience thirst as one of the body’s natural indicators of fluid needs. Another good indicator, Dr. Dutta says, is the colour of the urine.
"Pale yellow urine is usually a good sign that the person is well hydrated and dark urine could mean the person should drink more water,” he says. “However, urine colour should not be used as a medical test as some medicines, supplements and health conditions can also affect the colour of the urine,” he cautions.
The most important thing, according to him, is to maintain hydration for the entire day, not a set amount of glasses. “Drink as needed in response to thirst, activity and temperature, sweat, and sickness,” he advises.
When water becomes a problem for the kidneys
“People with CKD may need a specific fluid intake based on their kidney function,” Dr. Lata says. “In advanced stages, those with reduced urine output or fluid retention may be advised to limit their water intake under medical supervision,” she explains.
“CKD usually builds up silently from long-term diabetes or persistent high blood pressure,” Dr. Lata says. “Kidney stones, repeated infections and inherited conditions can also cause it,” she adds. “Once the kidneys are failing, extra water stays in the body. Swelling can spread to the legs, fingers and face, and blood pressure often rises,” she explains. “Too much water can also dilute the blood’s salt levels, which in serious cases causes confusion and seizures,” Dr. Lata cautions.
Simple tips to protect your kidneys
“If you already have a kidney problem, follow your doctor’s water limit, not the 3-4 litres a day rule,” Dr. Lata advises. “Keep blood sugar and blood pressure under control through regular monitoring and healthy habits,” she says. “Avoid unnecessary or frequent use of painkillers and other medicines without medical advice, as some can affect kidney health,” she adds.
Maintain a balanced diet, stay physically active and get regular kidney check-ups if you have risk factors such as diabetes, high blood pressure or a family history of kidney disease. More does always mean better.