Five facts you might not know about groundwater

A child pumps water by hand.

Groundwater is the most abundant and accessible source of freshwater available to humans. Today, groundwater supports 40% of irrigated crop production, sustains drinking water for more than a quarter of the world’s population, and helps maintain nearly half of all freshwater ecosystems.

Simply put, the future of humanity—our water, our food, and the environmental systems that support them both—depends on the conservation and protection of groundwater resources.

A WWF publication, Sustainable Groundwater Management for Agriculture, highlights the critical and often unseen roles that groundwater plays in our lives, how it is in trouble, and what we can do now to conserve it.

Here are five of the top things you might not know about groundwater:

1. Groundwater is the most abundant source of freshwater available to humans, despite being largely unseen. 

      Groundwater makes up less than 1% of the water on earth.

      The volume of groundwater is more than 30 times that of all the surface water sources like lakes, rivers, and streams combined! Even though groundwater is the most abundant source of freshwater, it makes up less than 1% of all water on Earth.

      Unfortunately, many regions that pump large quantities of groundwater for above-ground use do not regularly measure how much they extract. Even more concerning, few governments have set controls to keep groundwater extraction at sustainable levels.

      The climate crisis is worsening droughts worldwide.

      Remote controlled giant water sprinklers spray soy crops. Soy is an intensive crop, meaning large amounts of water are required to help it grow.

      2. Groundwater is a crucial resource for agriculture and food production, but that is where it is commonly over-exploited.

      Groundwater is most often extracted to irrigate agricultural land to produce food. It provides nearly 40% of the water used to irrigate crops.

      However, one-quarter of irrigated food production around the world relies on unsustainable groundwater extraction, which has huge implications in places like the US, Mexico, the Middle East and North Africa, India, Pakistan, and North China.

      3. We are consuming groundwater at an unsustainable rate, and climate change is making it worse.

      Even though you can’t see it, groundwater helps support half of all freshwater ecosystems by replenishing surface water, including rivers, streams, wetlands, and lakes. Freshwater systems above and below ground are closely interconnected, so if the groundwater level is pulled down just a few feet, the flow of groundwater into freshwater ecosystems would quickly decrease.

      Currently, groundwater systems in 20% of all river basins are being overdrafted, negatively impacting the river’s ability to provide water for drinking, crop irrigation, and habitats for freshwater species. More than half of all river basins are at risk by 2050 if current trends continue.

      Over-extracting groundwater can have additional impacts, including:

      1. Saltwater intrusion: the movement of seawater into groundwater supplied near coasts, which results in the ground becoming saltier and can kill crops.
      2. Dried up wells: the loss of accessible water in wells, often used for residential purposes, can increase the need to drill down further for water—an expensive and sometimes unattainable solution.
      3. Weakened geological layers: the collapse of land surface from weakened geological layers is referred to as ‘subsidence.’

      Groundwater flows into a rice field in the Philippines.

      Water bottles are filled from a spring in South Africa.

      4. Groundwater can be protected and recharged, and there are solutions available now.

      There is hope to recover or recharge groundwater and prevent additional overuse.

      Groundwater can be replenished both naturally and artificially, such as through human interventions to increase the amount of water that is percolating underground. Artificial (or managed) recharge is a key nature-based solution that can turn the tide on groundwater protection.

      The Edwards Aquifer in Texas is a powerful nature-based replenishment story. In 1993, the Texas legislature set a cap on groundwater withdrawals, with a goal of decreasing use by 2004, and then planned to set an even lower limit in 2008. However, Texas changed the approach in 2007 to be more reactive to decreases in aquifer levels, meaning extraction allowances would be tied to how groundwater levels impacted populations of endangered species within the region. By developing a legislative system that aligned groundwater withdrawals with environmental goals, and protecting zones near the aquifers for natural recharge, the Texas state legislature set an example for sustainable groundwater management.

      Overall, sustainable groundwater management involves the following principles:

      1. Measure and manage: collect and analyze local groundwater information to develop a sustainable management plan, including monitoring to verify the efficacy of the plan during implementation.
      2. Set sustainable limits: set limits or “caps” on the total volume of groundwater that can be extracted from an aquifer, along with volumetric allocations to each user and monitoring and regulation of those allocations.
      3. Recharge and replenish: enhance aquifer recharge through natural or managed replenishment.
      4. Reduce demand and maintain balance: manage demand and groundwater extraction to balance water use with replenishment.

      5. You can be part of the solution for groundwater.

      In 2015, as the South African city of Cape Town was nearing Day Zero—the day they would become the first major city to run out of water—residents, businesses, and the government joined forces to quickly transition how they viewed and used water. Three years after the start of the crisis, the city succeeded in reducing its daily water use by more than half.

      Groundwater is an urgent global issue. Everyone must take responsibility for how we use this shared and precious resource. The solutions listed above are applicable universally, but they must be designed and implemented locally and uniquely. And there is no time to wait.

      Learn more about the principles for sustainable groundwater management here.