This is a question that I’ve asked over and over again, but I get very few comprehensive answers.  Hopefully, by the time you’ve finished reading this you’ll have a better understanding of how much water you should be drinking over the course of a day.  It may confirm what you already know, but it might also throw up a few surprises you had never thought of.

Why Is Water Important?

Virtually every action your body’s cells take, involves the use of water; staying hydrated keeps every system in your body functioning properly; even a 1% drop in hydration, can lead to a 10% drop in athletic performance.  More specifically, water helps: carry nutrients and oxygen to all of your cells; flush bacteria from your bladder; aid digestion; prevent constipation; normalise blood pressure; stabilise the heartbeat; cushion joints; protect organs and tissues; regulate body temperature; and maintaining electrolyte balance, to name a few.  So you can see that having enough water is absolutely essential to your body’s function and health.

How Much Water Should I drink?

There is no exact answer to this as each individual need is different based on body composition, activity levels, and state of existing health conditions.  That said, there are a few general rules of thumb that you can use to estimate how much water you should be drinking, but it’s important to check your urine in order to ensure you remain hydrated throughout the day.  When appropriately hydrated, your urine should be a light straw colour.  If it looks like pure water that you could bottle and drink again, you may be drinking too much for your current levels of activity and would benefit from cutting back ever so slightly.  This is to avoid flushing out all of your body’s electrolytes, or throw off your sodium/mineral balance.  If your urine resembles a pint of Guiness, smells of Sugar Puffs, or could pass as a drink of Irn Bru, you really need to up your water intake.

You will hear the 6-8 glasses of water a day, but what does that actually mean?  How big are the glasses, and should someone twice the size of me be drinking 6-8 glasses as well?  The answer is of course not.  This is a general rule just to try to make you drink some water.  A more accurate amount for optimum hydration, is to drink 1 litre a day for each 25kg you weigh.  So if you weigh 100kg, you should be drinking 4 litres a day as a baseline.  On days where your activity is extraordinarily high, you may need to up that depending on the duration or intensity of your exercise.  Here is a calculation you could use, if you wanted to be a little more exact.

Weigh yourself before you start your activity and weigh yourself immediately after the activity.  For each kg of weight loss, consider that to be 1 litre of fluid lost.  Add to the weight loss, the amount of fluid you drank during the exercise, and this equals your total fluid lost during exercise.

For example: you train for 2 hours and weigh 100kg before exercise and 99kg after exercise.  During the exercise, you drank 1 litre of water.  Therefore, you lost 1kg from training, which equates to 1 litre of fluid loss.  But you drank a litre, so you actually lost 2 litres of fluid during a 2 hour training session.  You can, therefore, conclude that doing that particular type of training, you lose 1 litre of fluid per hour of exercise.

This could get a lot more complicated if you were training more than once a day, but let’s just assume you’re doing it just once a day.  This means that our 100kg person should drink 4 litres per day, plus an extra litre for each hour of exercise they do.

When Should I Drink My Water?

The average person can effectively metabolise and use, approximately 1 litre of water per hour, based on the ability of the kidneys to excrete this amount of fluid.  If you fit this general statement, then unless you have been undertaking significant exercise, anything over 1 litre an hour is just going to come out when you pee, taking a lot of essential minerals with it.  While extreme, this could actually kill you.  It’s called hyponatremia, and relates to blood sodium levels being too low.  Drinking more water than your body can handle is a very bad thing indeed, and on one end of the spectrum it results in things like cramp, headaches, and general sluggishness, but on the extreme other end of the spectrum, it can lead to death or colloquially called ‘land drowning’ or ‘water poisoning’.  So listen to your body, and try to stick to 0.5 to 1 litre of water an hour, depending on temperature and activity levels.  If you find that you’re behind on your water, drinking 400ml 45 minutes before a low to medium intensity workout that lasts for less than an hour, can sufficiently hydrate you, and allow yourself an opportunity to get back on track.

Don’t underestimate the importance of potassium and sodium when it comes to energy levels.  I’ll keep this basic, but essentially there is a sodium/potassium ionic exchange that occurs, that allows sodium and potassium to cross each other through a cell membrane and allows the sodium/potassium ATPase enzymes to assist in providing energy.  The bottom line is, that a mineral deficiency can make you feel sluggish and impact on the amount of energy you have.  This is why most high protein, low carb diets, confuse many people.  They blame the lack of carbs for feeling sluggish, when in reality, it’s more likely to be a sodium or potassium deficiency.

If you are cramping up during exercise, it is almost certain that you have a potassium deficiency, if you are cramping up after exercise has finished, you have a magnesium deficiency.

To make sure you have enough potassium and sodium, you could try adding 1/2 teaspoon of sea salt to a gallon jug of water and sip that through the day in accordance with the timing guidelines above.  To make sure you get enough potassium, you could add a little bit of cream of tartar to the same gallon jug.

I Drink A Lot Of Coffee And Fizzy Drinks

A time gone by, you will have been told that drinking coffee or diet soft drinks mean that you will need to drink more water.  Thankfully, peer reviewed science has finally caught up with sports nutrition and realised that the diuretic nature of these drinks is minute, and their water content actually leaves you more hydrated than had you not drank them.  Essentially, everything that has water content, counts towards your overall water intake.  But that’s not an excuse to drink a load of rubbish, you still need to be aware of the second order effects of too much of anything, regardless of how much water is in them.  Limit coffee and diet soft drinks to between 3 and 6 portions a day, combined, and I personally wouldn’t add them to my daily intake, but you can, just watch your pee to gauge your hydration levels if you do include them into your total.

How Much Water Should I drink?

To sum up, my generic bit of advice would be: 1 litre of water for every 25kg you weigh, plus additional water for added exercise or intense activity.  Try to drink 0.5 to 1 litre of water an hour, and if you find you are going over your maximum daily recommended amount, add a little sea salt and cream of tarter to your water in order to avoid a mineral deficiency.  But pay attention to YOUR body, and adjust accordingly.

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