Author Topic: The Water Myth  (Read 7503 times)

Pete McK

  • Sr. Member
  • ****
  • Posts: 374
    • View Profile
The Water Myth
« on: July 23, 2014, 10:25:57 AM »
I see that the Mountaineering Council of Scotland are warning about dehydration in this weather and peddling the same old drink at least 2 litres of water myth. The best advice I know came from my buddy who is a GP and outdoor enthusiast: Drink when you are thirsty, because your body knows best.

Lyle Brotherton

  • Administrator
  • Hero Member
  • *****
  • Posts: 939
  • Competent and safe navigation sets you free.
    • View Profile
Re: The Water Myth
« Reply #1 on: July 23, 2014, 11:21:19 AM »
It's the myth that just won't go away Pete and one close to my heart. When I was young we were taught that we needed 8x8 =  8 glasses of 8 ounces of water a day, yet later in life I discovered that this notion is based on flimsy and misinterpreted science.

Heather Morning, Mountain Safety Adviser with the Mountaineering Council of Scotland, who gave this advice has done so in good faith, she is excellent at her job and is no doubt in the same boat as the vast majority of folk about the issue of water intake.

The military have a keen interest in keeping their battlefield assets, a euphemism for squaddies, ready for action. Plus water is heavy to carry, 1 litre = 1 kilogram and it is a logistical problem to supply to the battlefield. As a consequence they have conducted loads of trials concerning hydration; from the simple let them drink what they want to intravenously introducing fluids into volunteers, another euphemism for you are going to do as your told, so the volunteers cannot tell how much fluid they have had in the tests.

It is thought that the 8x8 rule came from a recommendation by the US National Research Council, back in 1945, that adults should consume 1 millilitre of water per calorie of food they ingest, thus:

Men: 2500calories/day = 2.5 litres of water/day
Women: 2000calories/day = 2.0 litres of water/day

The floor in this reasoning is that all foodstuffs contain water and many at very high percentages:

Lettuce   95%
Broccoli 91%
Milk 89%
Orange juice 88%
Carrot 87%Yogurt 85%
Apple 84%
Chicken 68%

And we get between 25-40% of our fluids this way.

The second floor is that we get fluids from almost anything that we drink, from tea and coffee, the diuretic effect of these beverages is negligible, milk, fruit juice, and even light alcoholic drinks such as beer. So the guidelines to drink pure water is not only misleading, they are wrong.

The important thing is that if you are a healthy individual already drinking enough tea, milk etc., there is no evidence that drinking lots of water water as well will achieve anything other than making you pee frequently. In fact, over-hydration in itself can cause problems with electrolyte levels and blood sugar levels.

Adult male soldiers, who work in a temperate climate, consume on average 3,000 calories/day and drink on average 1.2 litres of fluids per day, of which pure water usually represents less than 25%, if at all. On very hot days with strenuous activity they may get up to 2 litres of fluid over the entire day, including breakfast and their evening meal.

Your GP mate is spot on about drinking when thirsty because we get thirsty long before there is any significant loss of bodily fluids. It takes less than a 2 per cent rise in the concentration of the blood to make us want to drink, while the body isn't officially regarded as dehydrated until a rise of 5 per cent or more.

As a footnote, I have been working on a project about water-purification in the outdoors and I will publish the results of this work on the Forum :)
« Last Edit: July 25, 2014, 07:55:23 AM by Lyle Brotherton »
“Opinion is the medium between knowledge and ignorance” - Plato

Lost Soul

  • Sr. Member
  • ****
  • Posts: 265
    • View Profile
Re: The Water Myth
« Reply #2 on: July 23, 2014, 01:26:54 PM »
Interesting and relevant thread for this time of year.  I sweat a lot so need lots of water, I try and drink on the when thirsty principle.  And I know only too well the problem of carrying the stuff around with me.  Particularly in summer.  I have a 3 litre Platypus.  In summer for a day out that gets filled up (6.5 lbs weight) and often as not on a hot day gets all used up .

In winter I half fill it and often return with 1/2 a litre or more.

As for a quick and simple test for checking correct hydration levels.  Signs seen in a Gentleman's Lavatory in a factory in Hertfordshire - you are wondering what is coming next aren't you.

Monitor the colour of your urine.  If you are properly hydrated it will be a pale straw colour.  The darker it gets the more dehydrated you are.  If it's clear then you are over hydrated then as Lyle says it can cause problems with electrolyte levels and blood sugar levels.

There have been some classic high profile cases of this happening.  Sian Williams the BBC presenter collapsed doing or at the end of the London Marathon a few years back from over-hydration.  She just drank every bottle of water that was handed to her with catastrophic results.  She ran again this year but with a carefully planned hydration strategy.  Not everybody survives the collapse as she did. 


Callum

  • Administrator
  • Hero Member
  • *****
  • Posts: 512
    • View Profile
Re: The Water Myth
« Reply #3 on: July 23, 2014, 03:54:23 PM »
The amount of youngsters who arri9ve at our centre with packs of bottled water yet at the same time poor footware is lamentable.

British tap water is probably the best in the world in terms of purity and where we live in the Lake District it tastes great too.

On our posting to Kenya we had an Old School CO. He insisted on the troops taking salt tablets and consuming a pint of tea every day. The tablets somehow found their way into the red dust and the one pint became two of tea, no dehydration, maybe this is why it is such a popular beverage in got countries?

The myth I would like to bust with water, and I totally agree with everything written so far in this thread, is that of bottled water being better for you because it is purer and contains minerals. I recently learned that one of the big bottled water brands is actually tap water to which they add minerals.

Of course we need minerals to maintain good health, BUT, the minerals that our bodies need and use do not come from water; they come from the foods we eat, including fruits, vegetables, and animal products. Less than 5% of minerals our bodies use come from bottled water if you were consuming the mythological 8x8 (2 litres) of the stuff per day. In fact, to get the necessary minerals from bottled water you would need to drink in excess of 840x8 of bottled water to get the RDA of most minerals

The bottled water industry is a multi-billion pound concern and it is their marketing strategies and paying for professionals to spout – forgive the pun - this nonsense which perpetuates this myth.

Lyle Brotherton

  • Administrator
  • Hero Member
  • *****
  • Posts: 939
  • Competent and safe navigation sets you free.
    • View Profile
Re: The Water Myth
« Reply #4 on: July 23, 2014, 04:01:17 PM »
A little off piste, but if you are travelling and need a supply of cheap bottled water Lidls sell a six pack for 99 pence - good to store in the boot of your car.
“Opinion is the medium between knowledge and ignorance” - Plato

krenaud

  • Jr. Member
  • **
  • Posts: 70
    • View Profile
Re: The Water Myth
« Reply #5 on: July 23, 2014, 05:31:07 PM »
Lyle,

Most bottled water, including Lidl's contains more bacteria than regular tap water and I would hesitate to keep it for any length of time in a car which can get quite warm in the summer.

But, for consumption within a short period from buying it, Lidl's water is a very good alternative to more expensive bottled water with fancy names.


Lyle Brotherton

  • Administrator
  • Hero Member
  • *****
  • Posts: 939
  • Competent and safe navigation sets you free.
    • View Profile
Re: The Water Myth
« Reply #6 on: July 23, 2014, 05:53:18 PM »
Good point Krenaud. Presumably they are all working to the same standards so unwise to keep any brand for prolonged periods.

One of the guys in TVMRT works for Scottish Water and he told me that none of the bottled waters meet the same quality standards as theirs.

Essentially all of our water in Scotland comes from rain, and when it rains two things can happen:

The water can flow into streams, rivers, lochs and reservoirs, and this type of water is known as Surface Water.

The other is the water seeps through the ground until it passes through. It then forms pools and this type of water is known as Ground Water. It is often very pure as many of the pollutants are naturally filtered out through the seeping process, similar to the portable filters available for walkers.

Ground water is usually the cleanest of natural waters; however it is frequently difficult to source and obtain. Stream water, though flowing, near its source is probably the next in terms of cleanliness, however it will contain surface water which, because it has flowed across the surface of the land can contain many contaminants, including animal faeces, which is why only filtering stream water is risky as these portable filters do not remove viruses - they filter to 0.1 microns and to filter viruses out you need to go to 0.02 microns.

I'll write more about this when my report is complete in the next couple of weeks.
« Last Edit: July 25, 2014, 07:56:34 AM by Lyle Brotherton »
“Opinion is the medium between knowledge and ignorance” - Plato

captain paranoia

  • Sr. Member
  • ****
  • Posts: 384
    • View Profile
Re: The Water Myth
« Reply #7 on: July 23, 2014, 06:37:51 PM »
Water and the amount that needs to be drunk by whom and when, is a subject of considerable contention.  Whilst hyper-hydration is certainly a problem, even partial dehydration is an issue, depending on who you are and what you're trying to achieve.  If you're a premier athlete, then even minor dehydration may impair your performance; that's why a lot of the hydration research has been done by sports scientists (I'm not talking about fizzy drink manufacturers here...).

On the other hand, there are plenty of people who say they never need to drink during a long day in the hills, and feel no ill effects; they just rehydrate when they get home.

Then there's the issue of whether thirst is a good indicator of dehydration.  One might imagine that evolution should have made our sense of thirst perfect, telling us to drink just when we need to.  However, evolution may have worked towards a different goal than the one we expect...  I think it's true to say that thirst is a variable indicator of dehydration, varying widely across the population.

I know that my sense of thirst is slow to act, and that I get lethargic, tired and confused if I get dehydrated.  So I have to take care to keep drinking.  I generally use bottles so I can see how much I've drunk; 'hydration packs' are convenient, but harder to track your fluid intake because the bottle is hidden away in a pack.

I read an anecdote from Dr Arnie Baker, author of 'Bicycling Medicine', where he drank 20l of water one day cycling in a desert in the US...

Bottled water?  Biggest rip-off out there...  I will sometimes buy a 2l bottle of water from Tesco's or Sainsbury's if I'm in town and thirsty; they're 20p or so.  The Sainsbury's one claims to be spring water, rather than filtered mains water.

Cruise liners often have sophisticated water treatment plants, desalinating water using waste heat from the engines (essentially, distillation).  Of course, this distilled water would taste odd, so they carefully add trace minerals to make it taste like spring water.  I think Coca-Cola's Dasani may be the water Callum heard about

http://en.wikipedia.org/wiki/Dasani

<boggles at PR gaffe of the original UK tagline...>
« Last Edit: July 24, 2014, 05:29:50 PM by captain paranoia »

Lost Soul

  • Sr. Member
  • ****
  • Posts: 265
    • View Profile
Re: The Water Myth
« Reply #8 on: July 23, 2014, 07:03:00 PM »
Back in the days of the Yuppie, bottled water was colloquially known as "designer water" the must have drink, that is where the rip off began.  And it is still with us.  Way back then Which? did some comparative tests designer variety vs tap. 

Of interest to me was the results for my area at that time - served by Thames Water.  Not literally stuff out of the river I might add.  Test results showed that tap water supplied by Thames Water was far purer and cleaner than anything found in a grossly overpriced bottle.

Also at the time I was travelling to France on business quite a bit and developed quite a liking for the Badoit brand of water.  That was until the same Which? report revealed that its content of Radon was way above acceptable levels in respect of radiation exposure.   :-[ Haven't touched that brand since.  Merlot is a nice substitute   :-\

Callum

  • Administrator
  • Hero Member
  • *****
  • Posts: 512
    • View Profile
Re: The Water Myth
« Reply #9 on: July 23, 2014, 08:30:19 PM »
I'll join you in the Merlot Lost Soul ;)

For all the logic and common sense afforded inn this thread my wife still insists that bottled water is purer and needs to drink copious quantiteis of the stuff every day :o

krenaud

  • Jr. Member
  • **
  • Posts: 70
    • View Profile
Re: The Water Myth
« Reply #10 on: July 23, 2014, 09:23:01 PM »
Lyle,

I'm interested to know if you have had a chance to look at drinksafe system filters which claim to be able to filter out viruses?

The website's info is a bit sketchy and no actual figures of the filter size are presented there unfortunately.

Lyle Brotherton

  • Administrator
  • Hero Member
  • *****
  • Posts: 939
  • Competent and safe navigation sets you free.
    • View Profile
Re: The Water Myth
« Reply #11 on: July 24, 2014, 08:21:23 AM »
Krenaud

Question: “I'm interested to know if you have had a chance to look at Drinksafe system filters which claim to be able to filter out viruses?

Answer: No

I am in the process of writing an article for Mountain Rescue Magazine about water purification in the great outdoors, following some work I have been doing with the Special Forces. Not dissimilar to the 8x8 myth, there is a great deal of subterfuge by the water filter industry and lots of advice on the net which is not based upon empirical science from the preeminent authorities in their field.

This situation is similar to that of snake bites, which i found when I needed to research the subject. Not all forums are the same ;) and many have barrack-room lawyer types who spout forth about all and sundry, with little to no knowledge whatsoever about what they are speaking about. I will post my most recent article about snake bites from the most recent issue of Mountain Rescue Magazine later today.

Plus, I will summarise for forum members my water purification work in the next couple of weeks.
« Last Edit: July 25, 2014, 07:26:01 AM by Lyle Brotherton »
“Opinion is the medium between knowledge and ignorance” - Plato

Lyle Brotherton

  • Administrator
  • Hero Member
  • *****
  • Posts: 939
  • Competent and safe navigation sets you free.
    • View Profile
Re: The Water Myth
« Reply #12 on: July 24, 2014, 02:36:17 PM »
This is the snake (British Adder) article I wrote, appearing in this month’s issue of Mountain Rescue Magazine 

After the incident, referred to in the article, I conducted the ubiquitous Google search and soon discovered a myriad of sites, from NHS Direct to various outdoor forums, all which proffered varying levels of varying advice. This variance was incredible and I later discovered many of the barrack-room lawyer’s advice, on many of the outdoor forums, was downright dangerous, even potentially fatal.

Which is why I set out to track down the preeminent world specialists in this field and elicit their expert advice. 

A simplified version of it also appeared in Trail Magazine and it is due to be published in a similar vein in some of the nationals and other journals.

« Last Edit: July 28, 2014, 07:31:39 AM by Lyle Brotherton »
“Opinion is the medium between knowledge and ignorance” - Plato

Oakleaf

  • Global Moderator
  • Jr. Member
  • *****
  • Posts: 59
    • View Profile
    • Profile on LinkedIn
Re: The Water Myth
« Reply #13 on: July 24, 2014, 03:39:20 PM »
Lyle - excellent article.

The only thing I'd add - at clear risk of proving myself a barrack-room lawyer  :o - is in terms of avoidance.

Spending a good deal of time on Cannock Chase, many adder incidents there occurred in April - with cold nights and sunny days. These seemed to draw reptiles out onto or close to paths in order to soak up heat. And until they had 'charged up' they tend to be quite lethargic; hence slower to move away. 

Certainly most of my encounters from that period fitted that exact 'mo'.


Lyle Brotherton

  • Administrator
  • Hero Member
  • *****
  • Posts: 939
  • Competent and safe navigation sets you free.
    • View Profile
Re: The Water Myth
« Reply #14 on: July 24, 2014, 03:57:02 PM »
Thanks Oakleaf:)

I really enjoyed researching this article.

David Lalloo is a fascinating person, spending much of his time in Africa advising NGO's about snake safety for the locals. Plus he is not only a professor in herpetology but also medicine!

I was surprised that nobody had collated this research before and various mountain rescue councils are adopting it into their SOP's - making it all worthwhile :)
« Last Edit: July 25, 2014, 07:57:11 AM by Lyle Brotherton »
“Opinion is the medium between knowledge and ignorance” - Plato