ABE - How We Use Water (Lesson)

How We Use Water

Water may seem abundant to us, but the water that we can drink is actually quite rare and limited. Roughly 97.5% of Earth's water resides in the oceans and is too salty to drink or use to water crops. Only 2.5% is considered freshwater. Most freshwater is tied up in glaciers, icecaps, and underground aquifers; just over 1 part in 10,000 of Earth's water is easily available for human use.

As water moves, it redistributes heat, erodes mountain ranges, builds river deltas, maintains organisms and ecosystems, shapes civilizations, and gives rise to political conflicts.

Food production is a thirsty business. It takes more than 1,900 liters of water to grow just one kilogram of rice - the staple food in many parts of Asia. But it is meat -especially beef and lamb- that is most costly in terms of water, given the amount of water need to grow the plants on which the animals feed, as well as the water they drink.

Irrigation is essential to feeding the world. Only 17 percent of the world's cropland is irrigated, but it produces more than one-third of the world's food. Agriculture is becoming increasingly industrialized. The chemicals that are used in the process runoff into rivers and lakes, leach into the soil, and contaminate the water we drink. Around 20 percent of all freshwater withdrawn is used by industry. This amounts to an average of about 130 cubic meters per person per year although more than half of this is used by hydropower plants, and for cooling in power stations, with much of the water being returned to its source virtually unchanged. 

Hydropower is the world's most important source of renewable energy. It produces neither greenhouse gases nor the pollutants associated with burning fossil fuels and tends to be more acceptable to people than nuclear energy. Dams harness water resources for food production, energy generation, flood control, and domestic use. During the 1990s, between US$32 and US$46 billion was spent annually on large dams. Up to 40 percent of irrigated land now relies on dams, and hydroelectric plants generate 19 percent of the world's electricity.

The proportions of each of these three types of use-residential/municipal, agricultural, and industrial-vary dramatically among nations. Nations with arid climates tend to use more freshwater for agriculture and heavily industrialized nations use a great deal for the industry. Globally, we spend about 70% of our annual freshwater allotment on agriculture. Industry accounts for only 10%.

 

Please view the presentation below before continuing in this module.

 

Need to Know Water Legislation

There have been a number of legal efforts made by governments to clean up existing water pollution and prevent future pollution. The following are important to know for the APES exam.   You will be expected to know what is covered (and not covered) by each piece of legislation (be specific!) and how it would be utilized to solve environmental problems.

Clean Water Act (CWA) of 1972:

Previously called the Water Pollution Control Act, the purpose of the Clean Water Act was to maintain the chemical, physical, and biological integrity of US waters, including wetlands, by regulating pollutant discharge into surface water.   CWA also regulates water standards for surface water and provides funding for public water and wastewater treatment.   It does not apply to groundwater sources (these are part of the SWDA below). The EPA (Environmental Protection Agency) is the primary enforcement agency for this legislation.

Safe Drinking Water Act (SWDA) of 1974:

This law ensures safe public drinking water in the US and applies to every ground and surface water public drinking water source. It does not apply to private or unregulated wells or to bottled water (which is regulated by the FDA).     SWDA requires the EPA (Environmental Protection Agency) to set drinking water regulations for contaminant levels so that public health is protected. It allows states to set additional regulations beyond federal standards.   Regulations must be based on a cost/benefit analysis and peer-reviewed scientific studies.

Explore more about both of these important pieces of environmental legislation in the sidebar.

Clean Water Act Links to an external site.

Safe Drinking Water Act Links to an external site.    

 

RESOURCES IN THIS MODULE ARE OPEN EDUCATIONAL RESOURCES (OER) OR CREATED BY GAVS UNLESS OTHERWISE NOTED. SOME IMAGES USED UNDER SUBSCRIPTION.