The most abundant compound in the human body, water makes up 55 to 75 percent of the body’s weight. For the average adult, that equates to between 10 and 12 gallons. From a functional standpoint, water serves to carry nutrients and oxygen to cells; cushion organs, tissue, bones and joints; remove waste products; and regulate body temperature.

Dehydration occurs when the body’s water output exceeds water input. Water is lost through perspiration, respiration, and elimination. Dehydration can impair body function and lead to heat exhaustion and/or heat stroke, which can be life threatening. In high heat, humidity, or times of high activity — like working outdoors or participating in athletic activities — perspiration, which cools the body through evaporation of fluids, increases. Exposure to the sun or sunburn can speed fluid loss, as can beverages with caffeine.

Fluid replacement is essential, but it’s best not to wait until you’re thirsty. Thirst is actually the first sign of dehydration, when people have already lost between 0.8 and 2 percent of their body weight to dehydration.

“Checking to see if your body is well hydrated is easy — just look at your urine. If urine is pale yellow in color, fluids would appear to be adequate. If urine is dark yellow or appears concentrated, more fluids are needed,” said Mary Higgins, K-State Research and Extension nutrition specialist. “Eight to 12 cups of fluid are recommended each day to replenish essential body fluids. Water is recommended as a majority of the fluid replacement because it is readily absorbed. Cool water is preferred because it is absorbed more readily than warm, hot or ice water.”

Before working in the heat, exercising or participating in athletics, Higgins recommends drinking 14-22 ounces of cool water. She also recommends drinking 1.5 cups of water every 15-20 minutes during exertion. Children should be encouraged to take frequent water breaks (one-half cup after each 15 minutes of activity). In order to make sure that people who work outdoors, athletes and/or active children get enough fluids to replenish fluid loss, consider weighing before and after an activity and drinking 16-24 ounces of water for each pound lost.

Sports beverages may be helpful to some athletes who are exercising more than one hour and in need of quick energy, but Higgins recommends diluting them with an equal part of water to help replenish fluids and reduce calories. Sugary beverages like sports drinks or carbonated beverages can add unnecessary calories.

Older adults also need to drink fluids, even if they are not thirsty. The ability to sense thirst declines over the years, so older people cannot rely on their thirst to prompt them to drink enough fluids. The ability to regulate body temperature easily also declines with age.

In addition to replacing fluids, experts also recommend wearing a hat with a brim; choosing loose, comfortable clothes that breathe; using sun screen; and taking occasional breaks to help minimize the effects of heat and humidity.

For more information on this topic, download the publication Liquid Assets: The Value of Fluids to Your Health from the Leavenworth County Extension Office Web site at: leavenworth.ksu.edu.