No-one can dispute that water is an essential for life, and always has been. Humans can survive for some weeks without solid food but depending on the conditions, only a matter of days without water. So companies like Nestle, Danone and the Cola companies who compete to sell us their brand of bottled water are providing an essential for the human population.
Or are they? Does our need for water translate into a NEED (as opposed to a WANT) for bottled water?
Let's look at what has become an accepted ‘fact’, the statement that we need at least two litres of water per day. What does that actually mean? Does it, as the purveyors of bottled water would have us believe, mean that we should drink at least two litres of water (preferably, of course, their brand) in order to remain healthy, beautiful and all the other things we need/want? Well, actually, no. It is certainly true that even as relatively sedentary individuals living in a temperate region like the UK, France and much of the USA, some two litres of water are inevitably lost from our bodies each day and have to be replaced. We lose water as vapour in our breath, as sweat and as urine/faeces, representing in total some five to ten per cent of the total body water content of a fully hydrated human each day. We need to produce urine to carry away some of the potentially toxic waste products of our body's metabolism, and depending on what we are eating and our pattern of activity, our bodies have to produce something over a litre of urine per day to do this. If we exercise in warm conditions so that we sweat more in order to cool ourselves, then we need to drink more water to replace that sweat loss. Eliminating wastes and keeping our bodies from overheating are essential, so it's true that on average, we do need to lose and replace around those magic two litres per day. And if we drink too much water, we just pass any excess out of our bodies as additional urine so over indulgence doesn't matter. Pass me the bottle of water, then, to keep me hydrated.
Fit to drink
But wait a minute. We need to take in two litres of water in total, not just as neat water. The basic composition of our foodstuffs means that we get the equivalent of something over a litre of water directly from that in the food we eat. Most food molecules also contain hydrogen that gets oxidised in our metabolism to produce hydrogen oxide (i.e water) in our bodies, the equivalent of some 300 ml per day. So that leaves something under a litre to be made up from what we drink. Some of that remaining amount comes from beverages like tea or coffee, or possibly even the milk on our breakfast-cereal. Which doesn't leave a lot that has to be made up from bottled water to keep us healthy. In the temperate regions where most bottled water is sold, the tap water is almost invariably fit to drink as a legal requirement on the water companies, so why not use that to make up the remaining need?
Bottled water is certainly not a physiological necessity in temperate regions, but there may be a case that it has a place in those hotter areas where losses through sweating are anyway higher and piped water supplies are either absent or likely to be contaminated. There, supplying clean water in bottles may be simpler, and even possibly less carbon-intensive than installing and maintaining fully piped supplies. The danger of reliance on damaged piped supplies has been brought home forcibly in the aftermath of the Haitian earthquake, with the recent outbreak of cholera from contaminated water. It reminds us that it is only just over a century since cholera was a major killer carried by the (then privately-owned) piped water supplies in London. Unfortunately, of course, the peoples of Haiti and other such areas where clean bottled water could have a major impact don't have the purchasing power to buy it. Unlike ourselves, with the purchasing power to satisfy both our needs and our whims.
Discarded plastic bottles
So if you are a comfortably well-off citizen of the temperate zone, next time you feel that you need to buy that heavily-promoted, fossil-fuel-dependent bottle of water, with all its associated imagery, pause for a second or two. Maybe you should just wander over to the tap and drink the perfectly safe water that comes from it. If you insist on having the water cold, fill a jug from the tap and stick it in the fridge ready for next time. If you are feeling really scientific, tot up how much water you are getting into your body anyway from food, beverages and so on, and see whether you really need any extra. Are you really thirsty, suggesting that you have a need for water, or is it just habit, a need to bolster your image or something equally non-physiological that is telling you to buy that bottle? That extra half litre won't do you any harm, but just think about the oil used to make the bottle, the pollution to the world's oceans caused by discarded plastic bottles and ask yourself, do you really need to spend money just to excrete an extra half litre of urine?