Drinking Too Much Water Can Kill You

By Dietitian, Juliette Kellow BSc RD

Health experts constantly encourage us to drink enough water to prevent dehydration and aim for 6-8 glasses a day. But after mum of two Dawn Page suffered an epileptic fit and was left brain damaged following advice to drink an extra four litres of water a day as part of an extreme detox diet, many of us have started wondering whether it’s possible to have too much of a good thing.

The answer in short, is yes! Like anything we consume, drinking excessive and extreme amounts of fluid – usually water – can result in ‘water intoxication’, a potentially fatal condition.

Ultimately, huge amounts of water upset the normal balance of electrolytes such as sodium in the body. For the body to function properly, concentrations of these electrolytes are held within narrow limits. If we drink a little more water than normal, our body effectively gets rid of the excess for example, in urine. However, if water enters our bodies more quickly than it can be removed, the electrolytes in our blood become diluted. When this happens, water passes from the blood into the cells and organs such as the brain, causing them to swell, which affects their normal function.

Early symptoms of water intoxication include light-headedness sometimes with nausea, vomiting, headaches and a general feeling of being unwell – in fact, very similar symptoms to those associated with dehydration! Unfortunately, if left untreated, mild symptoms can quickly lead to severe symptoms such as seizures, coma or even death within a few hours.

Fortunately though, water intoxication remains rare and is most commonly seen in inexperienced atheletes, where an individual takes in a huge amount of fluid but fails to replenish levels of electrolytes, which are lost from the body in sweat.

In contrast, dehydration is considered to be a much bigger problem for most of us. According to a survey carried out by the Tea Council, a third of all adults in the UK fail to meet daily fluid requirements. This is bad news as water makes up about two-thirds of our body weight. As a result, if we don’t get enough, our body works less effectively. In fact, while most of us could survive for weeks without food, a few days without water would seriously jeopardise our health.

As a priority, water is needed for most of the chemical reactions that occur in the body. It helps get rid of waste products and toxins in the urine, transports nutrients and oxygen around the body in the blood, acts as a lubricant for our joints and eyes, helps us swallow, helps control our body temperature, and cushions and protects our nerves.

Plus, staying well hydrated has been linked with better weight control, improved concentration, fighting wrinkles and even protecting us from major health problems like constipation, certain cancers, heart disease, gallstones and urinary tract infections.

A lack of fluid quickly leads to dehydration, triggering thirst in the first instance. However, the sensation of thirst only occurs when there’s already a water deficit in the body, so to prevent dehydration it’s important to drink regularly throughout the day and not wait until thirst kicks in before reaching for a drink.

Other symptoms of dehydration include small amounts of dark, cloudy and strong-smelling urine, headaches, poor concentration, tiredness, fatigue, irritability, dizziness, weakness, dry mouth and throat, chapped and dry lips, flushed skin and a fast pulse.

So how much should you drink? Ultimately, the amount of fluid needed each day varies from person to person, according to their age, sex and level of activity.

In hot weather or when we are very active, we tend to sweat more and so need more fluid to compensate for these losses. People with physically demanding jobs may also need more fluid if they sweat a lot. Illnesses that cause a high body temperature, vomiting or diarrhoea, all of which cause the body to lose extra fluid, need to replace these losses and should see a doctor if symptoms persist, as electrolytes may also need to be replaced.

Finally, women who are pregnant or breastfeeding need more fluid as the amount of blood in their body increases.

As a guideline, the Food Standards Agency recommends that if you live in the UK you should drink around 1.2 litres of fluid a day – the equivalent of around 6–8 glasses of fluid. However, you should drink more in hot weather, if you are very active or if you are ill. The World Health Organistion recommends even more, suggesting that men should aim for 2.5 litres daily and women, 2.2 litres daily.

With the exception of alcohol, all fluids including water, juice, soft drinks, tea and coffee count towards fluid intakes. However, if you’re trying to lose weight, it’s best to stick with low-calorie or calorie-free fluids such as water, sugar-free squash, tea or coffee with skimmed milk, herbal and fruit teas or diet soft drinks.

Many foods also contribute to fluid intakes, especially fruit and veg, which often consist of 85 to 95 percent water. And better still, they’re usually low in fat and calories but high in fibre, so will help to fill you up without filling you out!

Bottom line: water intoxication is not something most people need to worry about if they are healthy and eat a well-balanced diet that provides lots of different foods and contains sufficient fluid to prevent dehydration.