My wife is always getting on me about my water consumption. Apparently, she monitors my intake sufficiently, and is so knowledgeable about my hydration needs, that she can say with great certainty I don’t drink enough. Granted, she is an intelligent individual, and quite wise in her way, but I have to question the source of her data. How does she know how much I actually require? (She’s right though, I don’t drink enough) What about other sources of H2O? Can one dismiss so easily the water consumed in the many cups of coffee I drink? How much do I truly need for health and well-being? The answer is murkier than you might think. And these elicit very complex questions without concrete solutions.

Water is essential for life, a critical nutrient required by the body. Its absence is lethal within days. From the time primitive species ventured onto dry land, a key to survival has been preventing dehydration. Recent research has revealed crucial data regarding water’s importance for preventing non-communicable diseases related to nutrition, this because of the shift toward the increasing consumption of caloric beverages. Surprisingly, there is a tremendous gap in our understanding of proper fluid intake for individuals, as well as hydration in larger populations. To date, there are still no published, long-term, random-controlled trials on these topics.

Water comprises 75% of body weight in infants, significantly less in the elderly. All the cells of the body are filled with water, an absolute necessity for cell health and function, which is where approximately two-thirds of the water in our bodies is contained. The remainder is outside the cells, bathing most of the cells of the human body in a watery environment, the most hospitable for them. Despite these facts, there are still no established measures or markers regarding sufficient or healthy levels of hydration.

Recent research has revealed the precision and effectiveness of the regulatory system for maintaining water balance, at least to a healthy adult. The human body has a complex system to monitor and maintain fluid levels. Nerve centers in the brain, and various other organs (especially kidneys), are all part of the intricate network of checks and balances. Various hormonal pathways are also involved. Inadequate water levels lead to a higher concentration of the fluids outside of cells, resulting in water loss from inside. Two sensors in the brain detect this change and stimulate thirst as well as initiating the production of reduced and more concentrated urine.

Kidneys, part of the filtration system for our blood, function more effectively when there is an abundant water supply. When there isn’t, they require more energy to do their job of filtration. There is more wear on this vital organ without sufficient hydration. Further stress to the kidneys occurs when they are asked to filter greater concentrations of salt or toxic substances in the blood. Thus, drinking enough water helps maintain kidney health in numerous ways.

Everyone is thirsty on occasion, yet thirst plays only a small role in the control of water consumption in the general population. We generally consume fluids not to quench our thirst, but as a component of our nutritional intake, especially in foods like soups, beverages, even the typical liquid stimulants we imbibe (tea and coffee). Athletic activities can stimulate thirst. During physically challenging sports, 6 to 10% of body weight can be lost through perspiration, leading to dehydration if not replenished. Surprisingly, athletic performance is greatly affected by even mild water loss, as little as 2%. These alterations can include reduced endurance, increased fatigue, even reduced motivation, and seem to be exaggerated in endurance activities like tennis or long distance running. Rehydration reverses these deleterious consequences.

How much water does my wife want me to consume? Just “More!” Could it be too much? Is that possible? The typical admonition has been to drink at least eight 8-oz glasses of water a day, the prototypical 8 x 8 rule. This is generally followed by the reminder that beverages containing caffeine and alcohol don’t count. Actually, there is no proof for this recommendation and scientists state it all counts towards our levels of hydration.

Where did this 8 x 8 rule come from, some large scientific study? On the contrary, the only good studies of food and fluid intake strongly suggest that such large amounts aren’t needed. A critical factor is those surveyed were all relatively healthy. As mentioned, caffeinated drinks and mild alcoholic beverages like beer (in moderation) may indeed be counted toward the daily total.

Staying hydrated requires clean, potable water. We in the region of the Great Lakes tend to see water as abundant and cheap. Turn on the faucet and out it gushes, cheaply, for less than a penny a gallon. Water seems like the most renewable of all resources. It falls from the sky, and surrounds our land masses as the oceans covering most of our world. Americans use more water than any other country in the world, but rarely consider the consequences of our frivolous use to our rivers, aquifers, and other freshwater bodies. In many parts of the world, including some parts of the United States, there is a very different picture.

Climate change is bringing drought, as well as rising temperatures, to many parts of the globe. Pollution is accumulating in both freshwater supplies and underground aquifers. The depletion of aquifers can also make the water that remains saltier, more saline. Further adding to our hydration woes, fertilizers leach nitrates into the water table, making the water there unsuitable for drinking. Even its use for irrigation has been deemed dangerous.

But water is tremendously plentiful on this planet, a distinguishing factor allowing life to develop here. Unfortunately, most of the Earth’s water resources are inaccessible, the majority of it unsuitable for consumption. Additionally, water is hard to transport over any distance. And our need for fresh water is growing. Everything we do requires water, from drinking to washing, growing food, industrial uses, construction and manufacturing. With water tables falling in countries around the world, water scarcity is destined to become one of the biggest environmental crises of the coming decades. Farming, grain production, livestock, basically the world’s food production will all be affected.

Current population estimates state there are 7.5 billion people on the planet, with projections claiming there will be over 10 billion by 2050. The situation regarding water supply is clearly growing more urgent. Unless population growth can be slowed, many believe there may not be a practical, humane, non-violent solution to the world’s worsening water shortage. To some, especially those residing on the shores of one of the largest freshwater lakes in the world, this may seem like a distant concern. But human beings need clean, drinkable water, and without it, the human population, as a whole, is going to suffer.

Editor’s note: Dr. Conway McLean is a physician practicing foot and ankle medicine in the Upper Peninsula, with a move of his Marquette office to the downtown area. McLean has lectured internationally on wound care and surgery, being double board certified in surgery, and also in wound care. He has a sub-specialty in foot-ankle orthotics. Dr. McLean welcomes questions or comments atdrcmclean@outlook.com.