Why staying hydrated is so important

The human body is made up of 55% to 70% water, depending on your age. So it’s not surprising that drinking enough and staying hydrated is crucial to keep your body functioning at its best.

As we age, this could be more important than ever for helping us to live a longer and healthier life.

Results from a 2023 study suggest that people who are sufficiently hydrated may be less likely to develop chronic illnesses or show signs of ageing. Researchers analysed sodium levels in the blood of 15,700 adults, aged 45–66, for 25 years.

Drinking water is important for maintaining normal sodium levels, so the amount of sodium in someone’s blood can be used to measure how hydrated they are. Findings showed that people who had the higher end of a normal range of sodium in their blood had a 39% greater chance of developing chronic illnesses.

They were also 50% more likely to have biological markers of age older than their chronological age. Chronological age is the number of years you've been alive, while biological age refers to the physical age of your cells and tissues. 

Lesley Carter, a registered nurse and programme lead at the Malnutrition Task Force, which is supported by Age UK, agrees.

She explains that not having enough fluid can cause an imbalance of electrolytes, such as sodium, which can affect your overall health. “Drink around six to eight glasses or 1.5 litres of fluid per day,” she says.

Your fluid needs can vary and depend on a variety of factors, including your age, lifestyle, body size and climate. Authors of the study did note the need for more studies to confirm the link between hydration and ageing.

Benefits of staying hydrated – and what counts

Staying hydrated can provide many benefits for your health.

• It can help prevent urinary tract infections – by diluting your urine and ensuring you pee often. This allows bacteria to be flushed from your urinary tract before an infection can begin.
• It can ease constipation – drinking enough helps to keep stools soft and makes them move through the bowel and pass more easily. Carter explains this is especially important for people on certain medications that can contribute to constipation.
• Research shows increasing water intake can reduce or prevent headache pain.
• Boost cognitive function and mood – studies show that drinking water can have positive effects, particularly by maintaining visual attention and increasing alertness.
• Better breathing – Carter says drinking enough fluids means your blood will be well-oxygenated, which will help you to breathe well.
• It can improve sleep – there is increasing research into the link between hydration and sleep. According to the Sleep Foundation, staying hydrated can reduce sleep disturbances. 

“Fluid is not just about water. If you don’t like water and the thought of drinking eight cups is beyond you, you could have soup instead.” 

Carter also suggests a cup of tea or coffee, adding custard to puddings or a stew with gravy, as alternatives. 

“Make it work for you. Have things that you enjoy and you can manage."

Why some people struggle to stay hydrated

Some older people or those with chronic illnesses, such as dementia, can experience issues with drinking enough fluid.

Carter says: “As you age, you don't necessarily feel as thirsty or the need to drink as much as you did when you were younger.

“Some people don’t realise how important being hydrated is.”

Another issue, she says, is that those with a weak bladder may worry about being incontinent and choose not to drink so much because of that.

But Carter explains the idea that reducing fluid intake will reduce the amount you’re peeing is a myth. “When you drink less, your kidneys overact, and this can make you pee even more.”

Carter says people with dementia may have forgotten that they haven’t had a drink or that they need to drink throughout the day. 

“If they're living alone and they haven't got any reminders, they won't drink.”

Three top hydration tips

Carter’s top hydration tips for older people or those with chronic illnesses

1. Use a straw 

Some people’s throats can get a bit restricted, so they find it difficult to swallow large mouthfuls. Sucking the fluid through a straw helps it trickle down more easily.

2. Create drinking prompts

This is especially useful if you or someone you know has dementia.

Options include placing a sticky label, with a reminder to drink on it, above the tap or on the cupboard, or setting a phone alarm.

3. Make sure fluids are easily accessible

If you or someone you know is less able, make sure that a drink is available and within reach.

The Alzheimer’s Society has more tips  on supporting a person with dementia drink enough.

The Malnutrition Task Force has more advice on managing hydration.