Dehydrated Drivers as Bad as Drunk Drivers?

New research suggests that driving while dehydrated is equally as destructive as driving while drunk. Drivers who had consumed alcohol over the legal limit as well as drivers who were dehydrated made twice as many driving mistakes as those who were hydrated.

Not drinking enough water can cause drivers to make more mistakes, increasing their chances of a collision.


Comparing Dehydrated and Drunk Drivers

Drivers who were mildly dehydrated were twice as likely to make a driving mistake than drivers who were hydrated. This is the same as a person who has a blood-alcohol level of 0.08 percent.

A blood alcohol level of 0.08 percent is considered too high to drive. Researchers do not want to diminish the dangers of driving while intoxicated or under the influence of drugs, but they want to shed light on a danger that many drivers may not be familiar with. 

Mild dehydration can lead to “negative changes in mood and reductions in concentration, alertness and short-term memory, as well as headache and fatigue.” Symptoms can affect a driver’s ability to maintain focus on the road, resulting in limited driving skills.

How much water do you need to drink to stay alert on the road?

Drivers should drink 6.8 ounces of water an hour (approx. 1 16oz bottle every 2 hours). The “dehydrated drivers” were given just 0.8 ounces of water each hour which resulted in driving skills equivalent to those who had a blood alcohol level of 0.8 percent and legally unable to drive. 

Researchers also warned that driving in a hot car may lead to increased dehydration during a long journey, especially for those who do not drink to avoid stopping for a bathroom break.

Driving under the influence side effects


  • Negative mood change
  • Reduces alertness
  • Memory lapses
  • Headaches & fatigue


  • Changes mood & behavior
  • Impaired judgement
  • Memory lapses
  • Headaches & drowsiness

Samadi's Take

Whether or not you consider yourself “drunk” the law says you’re an offender if your blood alcohol is above 0.08%. Symptoms affect a driver’s ability to maintain focus on the road, resulting in limited driving skills. These findings highlight an unrecognized danger and suggest drivers should be properly hydrated.

Samadi's Tips

  • Driving in a hot car also may lead to increased dehydration during a long journey.
  • Stay hydrated during long car journeys; don’t avoid hydration just to get somewhere faster
  • Schedule bathroom breaks on long car journeys