Advice to drink eight glasses of water a day may be misleading, research finds

Woman pouring water into glass. People don't need eight glasses of water per day. (Getty Images)
People don't need eight glasses of water per day, scientists say. (Getty Images)

The advice to drink eight glasses of water per day to stay healthy could be misleading, a new study has found.

The research looked at data from 5,600 people across 26 countries with ages ranging from between eight days old to 96 years old.

It found that people may need less than this amount per day, but requirements can vary on an individual basis.

Read more: Woman diagnosed with multiple sclerosis after thinking she had trapped a nerve jogging

Scientists from the University of Wisconsin-Madison found that water needs peak for men in their 20s, while it remains the same for women from the age of 20 to 55.

Newborns turn over the largest proportion of water, replacing about 28% of water in their bodies every day.

Lead author of the study, Professor Dale Schoeller, said: “The science has never supported the old eight glasses thing as an appropriate guideline, if only because it confused total water turnover with water from beverages and a lot of your water comes from the food you eat.

“But this work is the best we’ve done so far to measure how much water people actually consume on a daily basis – the turnover of water into and out of the body – and the major factors that drive water turnover.”

The team found that men and women require different amounts of water, with men needing about half a litre more.

Read more: Single parents most likely to skip meals to cope with the cost of living crisis

Man drinking bottle of water (Getty Images)
Men see their water needs peak in their twenties. (Getty Images)

Scientists say the results of the study, which have been published in the journal Science, will have implications for global warming.

The authors hope that the study will be able to improve our ability to predict more specific and accurate water needs globally.

Read more: Teenager who mostly ate croissants for more than a decade finally recovers

Schoeller added: “Look at what is going on in Florida right now, or in Mississippi – where entire regions have been exposed by a calamity to water shortages.

“The better we understand how much they need, the better prepared we are to respond in an emergency.”

Co-author of the study, Dr Yosuke Yamada, said: “Determining how much water humans consume is of increasing importance because of population growth and growing climate change.

“Because water turnover is related to other important indicators of health, like physical activity and body fat percent, it has potential as a biomarker for metabolic health.”

However, it's always advised that you follow official NHS advice or ask your GP if unsure. The NHS Eatwell Guide recommends six to eight glasses of fluid per day, stating that water, lower-fat milk and sugar-free drinks, including tea and coffee, all count.

Additional reporting by SWNS

Watch: Are you fuelling your workout properly?