By Frances Smith

By now, you've probably heard that our bodies are primarily made up of water, and you might have even made a New Year's Resolution or two to drink more every day.

But even with that common knowledge, as many as 75 percent of Americans are still not getting enough water. In this daily battle against a chronic state of dehydration, it's important to understand water's impact on the body.

In all, water has seven main functions: transporting, dissolving, cleaning, reacting, padding, and regulating temperature.

Let's break each of those down and see how water keeps our bodies operating smoothly.

Transporting

An adult human body is composed of over 60 percent water, which would account for 90lbs in a 150lb person. A lot of that water is attached to molecules, such as proteins and carbohydrates, or inside of cells.

Much like ships carrying cargo up and down a flowing river, water helps transport the nutrients and oxygen necessary for growth and repair in these cells throughout our bodies. It also relays important chemical messages from hormones and clears out cell waste products, such as carbon dioxide.

Dissolving

If you've ever washed the dishes (I really hope you've done this at least once!), you've discovered that water is a powerful solvent that can dissolve most substances. The one thing that water can't dissolve is lipids, which are a group of molecules such as fats, oils, and waxes. Luckily, our bodies are super clever and have worked out a way to surround water-insoluble molecules with proteins so they can be transported with water.

Cleaning

When water passes through the body, it flushes through the five main organs involved in the elimination process that help clean out harmful organisms, chemicals, and substances. These organs are the liver, kidneys, intestines, lungs, and skin. Each of the organs is dependent on the availability of water to run its processes, such as regulating and filtering the blood, maintaining salt balance, carrying and filtering products through the intestines, removing toxic gases, and eliminating toxins through our sweat.

Reacting

The body is big bag of chemical reactions, and water is big part of making them happen. In some cases water has to be broken down, or hydrolyzed, to help these chemical reactions take place. For example, when sugar (sucrose) is digested into fructose and glucose, water is hydrolyzed as a part of this reaction.

Lubricating

Without water, we'd sound like the wooden floorboards in an old Victorian house. We would also be in a lot of pain! Water-based lubrication is used throughout our body to moisten and lubricate joints, the digestive tract, and even our lungs. When we breathe, our lungs are using a water-based lubricant called surfactant that aids in their opening and closing movements.

Padding

Water acts as a padding or shock absorber for our joints, keeping the two ends of the joint from smashing into one another as we run, jump, and play. Between each of our vertebrae in the spine, the vertebral discs are mostly filled with water, allowing us to bend and twist without the pain of the bones grinding together.

Regulating

In a study done on Ironman athletes competing in Kona, Hawaii, it was found that athletes sweat an average of 1.1 to 2.2 liters per hour! Water acts as a temperature regulator by releasing heat from the body through the blood vessels at the surface of the skin and then being dissipated through the skin as sweat. The water evaporating from the body as sweat also helps cool it.

So, how much water are you drinking per day? Hopefully, we've shed some light on why you are constantly hearing that you should drink more water. If not, I'll leave you with this last little tidbit -- the smallest amount of water required to excrete bodily waste products is 500 mL or about two cups of water per day.