Next to oxygen, water is the most essential nutrient for the human body. Dehydration is probably the most common cause of fatigue, headaches, elevated blood pressure, indigestion, constipation, muscle cramping, and joint pain. Most people do not get near the amount of water they need each day to prevent these conditions and ensure optimal health.

Without water, we would be poisoned to death by our own waste products. It is essential to proper kidney function. In fact, dehydration is typically the cause of kidney disorders, such as kidney stones. Water regulates the amount and concentration of uric acid and urea removed by the kidneys. If there is not enough water available to the kidneys, wastes are not removed as effectively and may build up as kidney stones.

Water is also vital for chemical reactions in the digestion and metabolism of the nutrients we ingest every day, including fat metabolism. It carries nutrients and oxygen to the cells through the blood and helps to cool the body through perspiration. Water also lubricates our joints. In fact, chronic dehydration is a major factor in osteoarthritis and back pain.

We even need water to breathe properly. Water keeps our lungs moist to take in oxygen and create carbon dioxide. It is possible to lose a pint of liquid each day through our breathe alone.

Drinking sufficient water also prevents water retention. If you don’t drink enough water, your body retains water to compensate. Paradoxically, fluid retention can be avoided and eliminated by drinking more water, not less.

So how much water should we drink and when should we drink it? We have all heard the general recommendations of eight to ten 8-ounce glasses per day. However, a more accurate recommendation should be based on your body weight. This recommendation is ½ ounce per pound of body weight per day, at the minimum. If you are fairly active (i.e., if you exercise regularly), you should consume 2/3 of an ounce per pound of body weight per day.

You may wonder if drinking this much water will have you going to the bathroom several times a day. Yes, at first. But if you increase your daily intake gradually over the course of a few weeks, your bladder tends to adjust and you urinate less frequently but in larger amounts.

You should also try to drink most of your water between meals. Drinking more than a half a glass of water during a meal will dilute the stomach acids and digestive enzymes needed to fully and properly digest your foods.

What kind of water should you drink? Water that has been filtered beyond the processes required for tap water is best. Tap water typically contains way too much chlorine and harmful minerals for optimal health. A growing body of evidence indicates that chlorine may be carcinogenic and also contribute to heart disease. Although chlorination is used to kill harmful bacteria, it appears that the risks may outweigh the benefits. And our exposure to chlorine may be greater with a shower than with the water we drink. Recently, scientists discovered that showers can release 50% of the dissolved chlorine and up to 80% of the THMs (like chloroform and tetrachlorine) found in tap water through a process called aerosolization. This process is greatly increased in hot showers. Once airborne, these chemicals can then be easily absorbed through our lungs and our skin.

There are several good quality water filtration systems available. Some of the better systems include ultraviolet light, a carbon-based filter, negative ionization, a static magnetic field, and/or reverse osmosis. There is also a relatively new product called microstructured water, which involves reducing the size of the water molecules through a mechanical or chemical process, thereby increasing the body’s absorption of the water. Avoid distilled water as your only supply because it has been stripped of all of its minerals and can actually lead to electrolyte imbalances. Shower filters should at least contain a high-density chlorine filter.

Also, do not count fluids containing caffeine or sugar towards your daily intake. Although these beverages contain water, they also act as diuretics, meaning they cause you to lose water, which contributes to increased dehydration. So for every glass of coffee, juice, tea, or soft drink you consume, drink twice that amount of pure water.

In short, the best way to adhere to your daily water intake requirements and ensure optimal health is to drink 16 ounces of pure water upon awakening in the morning and keep a water bottle with you throughout the day. And remember to avoid drinking much water during meals.