Although it’s widely known that proper hydration is a necessary part of preventing heat-related illness on the job, keeping workers hydrated requires some knowledge and action.

For instance, how much water should employers provide and how often do workers need to drink it? How cool does the water need to be? When should workers hydrate? Should employers provide alternatives to water? 

Thirsty for answers? Let’s look at what employers and workers should know and do.

Review the basics

NIOSH recommends drinking 1 cup – or 8 ounces – of water every 15-20 minutes while working in the heat.

Consuming water regularly, instead of drinking larger quantities at random, helps regulate the body’s metabolic cycles and allows it to better manage heat and heat stress.

“When we’re exposed to the heat, we’re sweating a lot and we’re losing a lot of liquid volume,” said Cristina Campbell Harris, industrial hygiene supervisor in the Department of Labor and Industry at Maryland Occupational Safety and Health. “We want to replace that volume over small intervals during the day. You want to be sure you’re drinking throughout the day and not just when you’re feeling thirsty.”

In the latter scenario, the worker may already be dehydrated and at greater risk of illness or injury.

Other signs of dehydration:

• Headache
• Fatigue
• Lightheadedness or confusion
• Flushed, red skin
• Muscle cramps
• Heat intolerance or chills
• Dark-colored urine

Make it easy to access

OSHA says employers should provide cool water for workers to drink and keep it “in a location that is familiar to the workers, near the work, easy to access and in sufficient quantity for the duration of the work.”

In California, “employers are required to provide water that is fresh, pure, suitably cool and available to employees free of charge,” said a spokesperson from the California Division of Occupational Safety and Health. “The water shall be located as close as practicable to the areas where employees are working.”

NIOSH recommends estimating how much water will be needed and designating someone to check on and secure water supplies, including individual drinking cups.

Keep it cool

Water should be cooler than 59° F, NIOSH says. Campbell contends that the temperature of tap water, especially in municipal systems, suffices.

“The idea behind the cool water is that you want it to be consumed,” she said, “and so if it’s too hot, you don’t want to drink it because it’s hot. And if it’s too icy cold, it’s harder to get more in. No one’s going around with thermometers, but people always ask, ‘What does “cool” mean?’ Somewhere between 50 to 60 degrees is considered cool.”

Don’t overdo it

Is there a cap on water consumption? Yes, NIOSH says. The agency cautions that drinking more than 48 ounces in an hour can “cause a medical emergency because the concentration of salt in the blood becomes too low.”

It’s called hyponatremia, or “water intoxication,” and it can cause the brain to swell. This condition can lead to headaches and dizziness, confusion, weakness, nausea and vomiting, seizures, coma, and even death.

Campbell said medical issues related to overhydration frequently coincide with some other kidney disfunction or dysregulation. 

“You physically can only take in so much at one time. But then also on the elimination side, you have to be able to eliminate that.” 

Hydrate before and after work

Experts find that it’s easier to stay hydrated during the workday if you’re already hydrated when you arrive at the jobsite.

Then, “hydrating after work helps you replace fluids lost during the day and decreases the overall stress and strain on your body,” the Virginia Department of Health says.

“It’s really important to consider your hydration status before you even start work,” Campbell said. “Because you can already be starting the day in a deficit if you had a tough day of work the previous day or had consumed caffeine, which is a diuretic (a drug that causes the kidneys to make more urine). So, take that into consideration before you even start work to think about, ‘Now I need to keep up with what I’m losing throughout the day.’”

Know these do’s and don’ts

OSHA says that substantial loss of electrolytes “can cause muscle cramps and other dangerous health problems.” The agency calls on employers to provide electrolyte-containing beverages such as sports drinks for jobs lasting more than two hours.

Campbell suggests using beverages with electrolytes to “complement” your water intake, not as an alternative.

“In the same way that overhydration throws off those metabolic processes, the reverse happens with too many electrolytes,” she said. “Too many electrolytes throws off some of the body system functions, and so we want to maintain balance there.”

NIOSH also cautions against using energy drinks, some of which contain electrolytes, for hydration. “Drinking several energy drinks per day can raise your caffeine levels enough to affect your heart,” the agency says. “High caffeine levels can be risky when added to the strain placed on your body by heat.”

The Virginia Department of Health, meanwhile, warns that consuming alcohol within 24 hours “can and will put you at increased risk of heat-related illness.”

And what about salt tablets to replace salt lost through sweating? NIOSH advises against it, adding that regular water and meal consumption will “almost always maintain hydration during work in the heat.”

The Cal/OSHA spokesperson agreed: “Water is the preferred and most effective way to stay hydrated on the job.” 

Hydration and heat-related rulemaking

A proposed rule from OSHA, released during the Biden administration, is aimed at protecting workers from heat-related illnesses and injuries and places an emphasis on hydration. (At press time, a virtual public hearing on the proposed rule had been scheduled for June 16.) 

Published Aug. 30, the proposal would require employers, in part, to provide 1 quart of water per employee per hour when the heat index in the work area reaches 80° F or the wet bulb globe temperature is “equal to the NIOSH Recommended Alert Limit.”

Meanwhile, six states (California, Colorado, Minnesota, Nevada, Oregon and Washington, according to OSHA) have adopted their own heat standards. 

Enforcement of Nevada’s heat rule began April 29. It requires employers with at least 10 workers to conduct a one-time job hazard analysis to identify work conditions that could cause a heat-related illness. If such conditions are identified, employers must develop a written safety plan that includes provisions on potable water.

Part of a proposal from the New Mexico Environment Department – which if implemented would, at press time, go into effect July 1 – is a provision of fluids. It would require employers to provide workers with at least 1 quart of drinking water per hour and make available hydrating fluids with electrolytes and carbohydrates. Employers also would be required to pause work to allow workers to hydrate.