How Much Water Do We Need To Drink? - THE FIT MUM FORMULA

How Much Water Do We Need To Drink?

Conventional wisdom will tell you that you need eight glasses a day.


Or two litres, whatever way you look at it. Is that really accurate for everyone?

Water is needed for just about every metabolic process in the body. It’s absolutely essential for optimal health that we get enough. That’s not the same as saying you need to drink gallons every day though, just enough to make you function at your best.

So how much is ‘enough’?

Conventional wisdom will tell you that you need eight glasses a day.

What counts towards fluid intake?

What is enough? Can you drink too much? The aim of this post is to answer these questions to the best of my knowledge.

We HAVE to drink – much of our body is made up of water and we lose it through sweating, going to the loo and even breathing. This has to be replenished. On another note, we need the correct balance of electrolyte minerals to keep our bodies at the right hydration level too, but that’s for another article entirely.

But as for the magic eight glasses, no one knows where that came from; perhaps a 1945 study that showed 2.5 litres of fluid enabled people to perform optimally, BUT this also stated that much of that fluid was already present in many foods we eat without the need to supplement with that much liquid on top. Someone who exercises will need more than someone who doesn’t. A large person needs more than a small person. On a hot day you need much more than in the depths of winter. There are more variables but I don’t want to keep you (or me) here all day.

Which drinks count?


Yep – tea, coffee, milk, juice, smoothies, anything that is liquid. Remember ice is water too, as are ice lollies and ice creams at body temperature (if you ever thought ice cream stayed solid in your tummy, then sorry to burst the bubble on that revelation).

So how much DO you PERSONALLY need?

Are you thirsty?

Yes? Have a drink.

No? Don’t bother. It’s that simple. No, if you feel thirsty you are not already dehydrated. Just have a drink, that’s all you need to do.

Still not sure? Check the colour of your urine; it should be pale, not dark and/or very smelly.

STILL not sure?


how much water to drinkAccording to the National Institute of Health, the first signs of dehydration are:

  • Feeling thirsty
  • Dry or sticky mouth
  • Low or no urine output; urine looks dark yellow
  • Sunken eyes
  • Lethargy

SEVERE dehydration can lead to serious problems, such as comas.  It’s unlikely most people will get that badly dehydrated with the access to clean water we have in the UK.

What  about overhydration?

There are various reports, including one from 1996 that made the American guidelines read that we should drink as much as possible during exercise. The sports drink and bottled water industry loved this, and ‘more is better’ became the mantra of the day. Unfortunately there’s a condition called hyponatremia, which unbalances electrolytes, and has potentially very serious, potentially fatal, consequences indeed.

The brain gets confused from all the fluid the body is taking on board, reads that the person is in fact dehydrated, and halts urine production.  Organs, including the brain, become bloated and swollen with all the fluid, which leads to oxygen not being able to get through.

Ironically, statistically the people who develop the condition are mostly marathon runners……because they drink, and drink, and drink…because they’ve been told to.

Sports drinks & electrolytes

Unless you are exercising and sweating for many hours a day, your electrolytes don’t actually fall that much. Drinking water is adequate. The electrolyte balance will be restored, if needed, as soon as you consume your next meal. Exercising in the heat or for longer durations? Liquids containing either electrolytes, glucose, or both, could be beneficial or even essential. Speak to a coach or sports dietician to decide whether you need sports drinks.

awesome supplements electrolytes


The body gets used to caffeine pretty quickly so a person who regularly consumes caffeine won’t get as much of a diuretic effect. On average, 50mg caffeine equates to 60ml fluid loss, so if you’re drinking a 250ml coffee containing 100ml caffeine, you’re still taking on board fluid, not losing it.

To summarise:

Drink when you are thirsty.

Drink enough so that your urine is pale and not too smelly.

Don’t waste money on bottled water (tap is fine, just ideally filter it first), sports drinks or energy drinks unless exercising for long durations or in warm environments, or if you sweat a lot.

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