A new study found that about two-thirds of the world’s population, or some 4 billion people, face severe water shortages during at least one month of every year. Half of the 4 billion are in India and China, but people in other countries, including the United States and Mexico, are also affected.

“Most water is used for food, so water scarcity primarily translates to decreasing or failing crop yields,” wrote study co-author Mesfin Mekonnen in an email to SafeBee. Mekonnena is postdoctoral researcher in the department of Water Engineering & Management at the University of Twente in the Netherlands.

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The study, which used computer modeling to generate a snapshot of monthly water availability around the globe, painted a much grimmer picture than previous research, which focused on annual assessments. The authors say annual estimates hide month-to-month variations in supply and demand and therefore underestimate shortages.

While there’s enough freshwater globally to meet current demands, it’s not necessarily available when and where it’s needed, they note.

“The increasing world population, improving living standards, changing consumption patterns, and expansion of irrigated agriculture are the main driving forces for the rising global demand for water,” write the authors.

“High water scarcity levels appear to prevail in areas with either high population density (for example, Greater London area) or the presence of much irrigated agriculture (High Plains in the United States), or both (India, eastern China, Nile delta).”

Much of the water used globally goes to agricultural irrigation, and shortages can mean crop failure, low crop yields and higher food prices.

Of course in the United States, water shortages like those caused by the drought in California lead to rationing of water used to take showers, water lawns and wash cars. In California right now, restaurants won’t serve you water unless you ask for it. In poorer countries, some people don't have enough drinking water, period.

Related: 15 Easy Ways to Conserve Water

What can we do?

“We need to act to address the problem,” Mekonnen told SafeBee. “Governments, business and average individuals have a part to play in this regard.

"I wish a real discussion [would] start on how to manage water sustainably. In most parts of the world, water is underpriced, and few people realize most of the water they use is not in the house when they take a shower and water their garden."

But it's not showering or gardening that uses up the most water. "Most of the water an individual consumes comes indirectly through the food we consume — from far-away places. We need to be aware of our consumption pattern and ask how the product is produced — through sustainable agriculture or by drawing down the groundwater?”

When asked if there is one thing average individuals can do to help conserve water, Mekonnen answered, “Yes, consume less animal product. Select the food which requires less water to produce — for example a cup of coffee requires 140 litre compared to 35 litre for a cup of tea. 1 kg of beef requires on average 15000 litre of water. So the decision we make in consuming one or the other has an effect on the water use far away from home.”

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Marianne has been producing content that informs and inspires for more than 20 years, with a deep focus on bringing readers accurate, actionable advice and helping them live healthier, safer lives. Before launching SafeBee, she was executive editor of Sharecare, the health website and social network. Previously, she developed more than two dozen illustrated consumer health books for Reader’s Digest. Her writing has appeared in numerous outlets including Arthritis Today and WebMD. Her favorite safety tip: Know the purpose of every medication you take and under what circumstances you can stop taking it.