How Much Water Should You Drink a Day?
With water making up to 60% of the human body, it’s no question how crucial good hydration is for keeping your body functioning healthily. Water is essential for digestion, body temperature regulation, removing waste from our bodies, as well as our heart and brain function (and much more!) but how much water should I drink?
We need to drink enough water to replace the liquid we lose throughout our day; which is about 1.5 litres of fluid a day through urination, about 200ml through defecation, and around half a litre through your sweat each day - you also lose fluid just by breathing!
The Eatwell Guide, referred to on the NHS website, states that we should be drinking between six and eight cups of fluid daily - which is around 2 to 2.5 litres! Whilst some of our daily fluid intake comes from our food (such as soups/stews or vegetables and fruits), as humans, most of our fluid consumption comes directly from the liquids we drink.
Are There Factors That Impact How Much Water Should I Drink?
The exact amount of fluid you need to drink in a day depends on the following:
Your age - as we get older, our bodies are less efficient at storing water and our kidneys lose function.
Your lifestyle and physical activity levels - the more exercise you do, the more you’ll need to drink to replace the liquid lost through sweating.
Your surroundings - the climate and environment you live in also play a role, the hotter the weather, the more you’ll sweat, and the more you should be drinking to replace that lost fluid!
Your health - if you’re pregnant or breastfeeding you are more likely to become constipated and so you’ll need to drink more. You’ll also need to drink more if you’re recovering from an illness, on certain medication, or consuming alcohol.
What Does Water Do For The Body?
According to Mitchell and others (1945) The chemical composition of the adult human body and its bearing on the biochemistry of growth: Journal of Biological Chemistry:
The lungs are composed of of 83% water
Your muscles and kidneys are 79% water
The heart and brain are made up of 73% water
The skin contains 64% water
Even your bones comprise of 31% water!
There are many reasons to drink water, it is a vital nutrient to the life of every cell in our bodies. Water’s functions in the body can be divided into 4 categories: 1) transportation, 2) a medium for chemical reactions, 3) a lubricant/shock absorber, and 4) as a temperature regulator.
It’s through water that we dissolve minerals and nutrients to make them accessible to the body, and also carries nutrients and oxygen to our cells. The carbohydrates and proteins from our food are metabolised and transported through the bloodstream in water - and it even assists our kidneys and livers by flushing out waste through urination and defecation!
Through sweating and respiration, our body uses water to regulate our internal temperature - this is because water is good at storing heat, so it takes lots of external energy to raise its temperature. This is hugely important as the human body can only operate successfully within a narrow temperature range; an internal body temperature that’s too low or too high will cause enzymes and the body’s metabolism to stop working. If internal temperatures raise to 44°C, the central nervous system will stop working. Whilst if temperatures drop to 28°C, then muscle failure and hypothermia will begin to occur.
Water forms saliva and moistens tissues in the eyes, nose and mouth. It lubricates joints, and even acts as a shock absorber for brain and spinal cord (protecting your organs and tissues). For pregnant women, water is a key component of amniotic fluid, which delivers cushioning protection around the developing foetus.
What Are The Symptoms Of Dehydration?
Even mild dehydration can have a negative impact on your overall energy levels, mood, memory, and brain performance - so it’s important to know the signs!
The most obvious sign is thirst! But babies, children, and elderly people are most at risk of dehydration - both because their low body weight (which makes them more sensitive to any amount of fluid loss), and because their thirst perception is diminished and they are less likely to be aware they're becoming dehydrated. So whilst feelings of thirst may seem like an obvious symptom of dehydration, for many it can be useful to look out for other clues!
Whilst it’s not an exact science, your pee can provide some guidance towards your recommended water intake and hydration status; according to the NHS website, most people should aim to drink enough during the day so their pee is a “clear pale yellow colour” - if you’re dehydrated, it’ll be darker and likely stronger-smelling.
It’s also important to pay attention to how you’re feeling, any signs of lethargy, light-headedness, dizziness can be a sign that it’s time to drink more water! Having a dry mouth, tongue, and lips, sunken eyes, and urination less frequently than usual are also symptoms to watch out for.
With severe dehydration, a person can experience all of the above, as well as a weak or rapid pulse, seizures, a lower level of consciousness, weakness, and confusion - the person may also not have passed urine for up to eight hours.
Dehydration can happen to anyone, but it’s more likely if you are diabetic, have been experiencing vomiting, a fever, diarrhoea, or heatstroke, drunk too much alcohol, sweated too much after exercising, or been taking diuretics.
Can You Drink Too Much Water?
People are often concerned over the possibility of drinking too much water, and whilst this is rare, water poisoning is possible. Drinking a lot more than the recommended amount of fluid each day can cause overhydration, which results in very low levels of salt and an electrolyte imbalance.
Some of the symptoms of drinking too much water include:
Nausea and vomiting
Headache
Cramps or spasms
Unconsciousness
Confusion
Muscle weakness
