Print Page

The Human Body and Water

Humans are mostly made up of water: between 60-70 percent of our body mass is water, 70 percent of our brains are composed of water and our lungs are made up of almost 90 percent water. More than 80 percent of our blood is water, which is essential for food digestion, waste excretion and regulating body temperature. In order to properly function, humans should replace 2.4 liters of water daily, either through drinking or via eating food.




Humans can survive only 5 to 7 days without water, although we can live about a month without food. Many parts of the world – an estimated more than one billion people – lack access to safe drinking water, while an estimated 2.4 billion people lack inadequate sanitation.


The proportion of households in major cities that are connected to piped water (house or yard connection) in each continent are as follows:


Africa – 43%

Asia – 77%

Europe – 92%

Latin America and the Caribbean – 77%

North America – 100%

Oceania – 73%




In areas where water scarcity is not a problem, humans may use much more water than they realize. For example, we can take a five-minute shower with a standard showerhead, which uses 100 liters of water (26.5 gallons), or we can choose a low-flow shower head, which uses less than 50 liters of water (13.25 gal). Hand washing with the tap running can use up to more than five liters (1.3 gal); brushing teeth with the tap running can add up to almost eight liters; watering a lawn uses 35 liters per minute.


As the population of Earth grows exponentially, it is increasingly important for every person on the planet to be aware of how much water he or she consumes and wastes.  Think about this: If every human on Earth saved just one drop of water each day, the annual savings would be over 24 million gallons (90,849,882 liters)!  Imagine how much water could be saved if you cut back on a shower for just a few seconds…


Author: Joel Gershon

Products for Water Quality

Learn about HM Digital's line of water quality testing products.

Did You Know?

Water is our planet's most precious resource.

  • The average American uses about 50 gallons (190 liters) of water daily.
  • Flushing a toilet uses 2 to 7 gallons (7.5 to 26.5 liters) of water.
  • A five-minute shower uses 25 to 50 gallons (95 to 190 liters) of water.
  • Leaving the water on while brushing your teeth wastes 2 gallons (7.5 liters) of water each time!
  • At least 400 million people live in regions with severe water shortages.
  • Water is the original health drink.  It contains no fat, no calories and no cholesterol.