Bottom line up front: Unless you are working hard, actively playing sports, are working out too many hours in a single day, or have an actual health issue – you probably need less than a gallon of water in a single day. If you are urinating too many times and your urine is clear, back off a little if you want. There is no benefit to gain by adding more water. (See the final paragraph if you just want the punchline.) And, yes, it is possible to become quite ill or even die from drinking too much water, however both are extremely unlikely unless you are a marathoner or drink gallons of water.
Pretty much every day, I drink a “good amount” of water. As a Search & Rescue professional, we constantly remind each other to “hydrate, hydrate, hydrate”. Sure, you can imagine that a group of SAR team members, athletes, construction workers – anyone that works hard and out in the elements – is going to need to replace the water they are sweating out. But what about the average person at work, school, or home?
Why are we told to drink a gallon of water, is that scientific, and what does it do?
Trainers everywhere, including myself, are constantly telling people to drink water. In the next several words I will explain why I do it and why I use a little bit more prescriptive method than just “drink at least 1 gallon of water every day”. Hopefully, the science behind what I recommend will help you to better understand the importance of plain old water where it relates to your fitness and wellness.
Wait, wait, wait. So, you are telling me that my 200 pound self and my friend who works at the courthouse weighing in at a whopping 115 pounds both need to drink at least a gallon of water every day? Call me inquisitive and show me the evidence.
At somewhere between 50% and 70% of our body content, water is the primary component of our bodies. This is one reason it is believed we should drink “at least a gallon” every day. Water is used in several chemical and mechanical functions in the body. Bodily fluid balance is regulated through osmoregulation by the hormone vasopressin and the kidneys. Often, I speak of homeostasis in the healthy human. Homeostasis is balance of function in our systems. If you, the reader, are a healthy individual, your body is going to over-regulate the amount of water you drink that surpasses your actual need. In other words, you will pee.
Every human, and all animals for that matter, need water. It is essential to life. It helps with digestion, it helps with body temperature regulation, and it even helps with blood pressure. All of our waste is carried away from our cells in water. Our mitochondria, my favorite topic, use water in the glycolitic cycle as it produces ATP from pyruvate (my advanced clients are familiar with the power generation process at the cellular level).
Chances are really good that you will never suffer from hyponatremia – the dilution of blood chemicals (sodium) to a dangerous point – from drinking too much water. If you do, it could become life threatening. In my life, I have never personally known a healthy person who has drunk so much water that their blood chemistry was effected. There are plenty of reports of it happening to marathon runners who
As you go through your day, your body will tell you when you need to up your intake of H2O to help keep you from dehydration. If your urine is dark (unless, like me, you have the pleasure of coffee darkening your urine), you need more water. If you feel thirsty, you need more water. If you have a mild headache, you may simply need more water.
“Under normal circumstances of diet, exercise and climate the minimal urine output for healthy subjects is about 500 ml/day. Intake of more than 500 ml of fluids per day will result in the excretion of solute-free water. The recommended total daily fluid intake of 3,000 ml for men and of 2,200 ml for women is more than adequate. Higher fluid intake does not have any convincing health benefits, except perhaps in preventing (recurrent) kidney stones.”
–Arend-Jan Meinders, Arend E Meinders
Will it hurt if I drink a gallon of water even if I don’t need it? I am certain you are safe from harming yourself. From experience, I can tell you that if you do not need the full gallon it means more trips to the bathroom at all hours of the day. On the other hand I can tell you from being on operations in hot climate areas that a full gallon can be insufficient. When your clothing is literally soaked, you are breathing heavily for hours, and you have not had any other liquids, you can find yourself in a state of distress quickly. For that reason, I err on the side of drinking more water than you need rather than not getting enough.
Whatever you do, hydrate!