Drinking enough fluids is one of the most important things you can do to prevent heat illness. Water is generally sufficient for hydration.
Hydrate Before Work
Being hydrated when you start work makes it easier to stay hydrated through the day.If you are dehydrated when you start work, you may not be able to drink enough to catch up with your body’s need for water.
Hydrate During Work
Drink before feeling thirsty. By the time you feel thirsty, you are already behind in fluid replacement. Dehydration is a primary contributor to heat exhaustion.
Your work performance may suffer when you are dehydrated, even if you don’t notice.
When working in the heat, drink 1 cup
(8 ounces) of water every 15–20 minutes.
This translates to 3⁄4–1 quart (24–32 ounces) per hour.
Drinking at shorter intervals is more effective than drinking large amounts infrequently.
Do not drink more than 48 oz (11⁄2 quarts) per hour! Drinking too much water or other fluids (sports drinks, energy drinks, etc.) can cause a medical emergency because the concentration of salt in the blood becomes too low.
Hydrate After Work
Most people need several hours to drink enough fluids to replace what they have lost through sweat. The sooner you get started, the less strain you place on your body from dehydration.
Hydrating after work is even more important if you work in the heat on a regular basis. Chronic dehydration increases the risk for a number of medical conditions, such as kidney stones.
DEPARTMENT OF HEALTH AND HUMAN SERVICES Centers for Disease Control and Prevention
National Institute for Occupational Safety and Health