By Patty Smith*
Around the world, people use many gallons of fresh water every day. Yet many have only a basic knowledge about the availability of fresh water, its proper management, or the processes and technologies that regulate the accessibility and conservation of this precious resource.
The Earth is literally awash in water—71% of its surface is liquid, representing more than 326 million trillion gallons of water. However, a minuscule amount of that vast resource is available as fresh water. According to data from Pennsylvania State University, only 3% of the Earth’s water is fresh, with the remaining 97% salinated or ocean water.
Of that 3% fresh water, 69% exists within glaciers, and 30% is underground, which means less than 1% of fresh water is readily accessible for use in lakes, swamps, and rivers.
Where is the fresh water used? A report published in 2021 by the United Nations-affiliated organization, UN-Water, stated that globally, 72% of all water withdrawals are used by agriculture, 16% by municipalities for households and services, and 12% by industries. Individuals can evaluate their personal, household water usage with this free online water-use calculator offered by GRACE
Water Scarcity is a Global Concern
When discussing the availability and use of fresh water, attention should be paid to the scarcity of water around the world. The numbers are sobering. An area is said to be “water-stressed” when it withdraws 25% or more of its freshwater resources. According to the UN-Water report, 2.3 billion people live in water-stressed countries, of which 733 million live in critically water-stressed countries. According to UNICEF, 1.42 billion people—including 450 million children—live in areas of high or extremely high water vulnerability. In addition, a report published in 2020 by the UN’s Food and Agriculture Organization said that 3.2 billion people live in agricultural areas with high to very high water shortages or scarcity, and 1.2 billion people—roughly one-sixth of the world’s population—live in severely water-constrained agricultural areas. These numbers underscore the need for effective water management and water conservation practices.
Effective Water Management Systems Can Help
The first step in water conservation is evaluating water management systems. Effective water management means water resources are allocated judiciously with the goal of ensuring sufficient water for human and environmental needs. The elements of an efficient water management strategy are: access to water, control of pollution, and water efficiency or reducing the amount of water that is wasted. Moreover, water management planning should be aware of current engineering technologies and relevant political, economic, and social agendas.
The following are a few reliable water conservation systems and practices that have stood the test of time.
Rainwater harvesting (RWH)
Rainwater harvesting (RWH) is one of the simplest and oldest methods of supplying water to households, farms, schools, public facilities, neighborhoods, and communities. As the name suggests, RWH is the collection and storage of rain to be used as a supply of fresh water—a practice that’s been used for thousands of years. Rainwater is typically collected from roof-like surfaces and directed towards a tank, cistern, barrel, or other containers for storage. RWH systems range in complexity from basic systems that can be installed with little more than minimal plumbing skills, to automated systems that require professional installation.
The advantages of RWH systems are that it is an independent water supply during times of water restrictions or drought; it is cost-effective and can be affordable; and it is eco-friendly and does not cause pollution.
The RWH limitations are that only minimal quantities of water can be harvested in periods of low precipitation. Also, although rainwater is a relatively clean source of water compared to groundwater or water from lakes and rivers, untreated rainwater is unsuitable for drinking or cooking. Water collected from roofs can be polluted with bird feces, mosses, lichens, and windblown dust, and the rainwater itself can carry bacteria, viruses, parasite, and toxic chemicals. Thus, water from RWH must be filtered and purified before consumption.
One of the ways that developed countries have used to access water is by creating a rainwater distribution system to capture rainwater for immediate and future use. Countries worldwide have already completed the task of implementing designs to capture rainwater. By creating funding opportunities for local governments and individual homes, rainwater distribution has become an avenue to utilize water sources in a conservation manner. One company, Chaitanya Rainwater Products and Systems, has designed systems used in Singapore, Japan, Germany, and Australia to capture rainwater for commercial use; its products can be scaled for individual use.
Reusing “greywater”
Reusing “greywater” is another way to substantially conserve water. Greywater refers to the wastewater produced in households or office buildings from activities such as washing one’s hands, showering, using a dehumidifier, and washing laundry. Greywater does not include water from toilets or urinals and does not contain fecal material. Since greywater contains fewer pathogens than domestic wastewater, it is generally safer and easier to treat and reuse for such non-potable purposes as irrigation or flushing the toilet.
The National Center for Biotechnology Information (NCBI) reports that greywater accounts for approximately 75% of sewage, accounting for 69% domestic household use. The average person uses about 100 liters (a little over twenty-six gallons) of water per day or close to 146,000 liters (approximately 39,000 gallons) for a family of four per year.
Current technology designs can capture this water for agriculture and landscape irrigation, household uses, and artificially recharging aquifers. Different systems have been used globally to minimize freshwater resources in water-scarce regions and alleviate water pollution, particularly in low-poverty areas. The NCBI has collected data reflecting the current uses of greywater systems for various countries.
Desalination
Desalination is any process that removes salts and minerals from saline water, and is another way to provide fresh water to areas of water scarcity. The US Geological Survey (USGS) cites a report from the International Desalination Association stating that as of June 2015, there were 18,426 desalination plants worldwide, contributing 86.6 million cubic meters per day (approximately 23 million gallons) of fresh water. Countries such as Saudi Arabia, Bahrain, and the United States, have already invested in building desalination plants and funding research and development of new technologies.
The processes of desalinating seawater are generally more expensive than obtaining fresh water from surface water, groundwater, water recycling, or water conservation practices. Yet, these alternatives are not always available.
While new technologies are in development, two of the more common methods of desalination are thermal technology, a method invented 2,000 years ago, and membrane technologies designed in the 1960s. Thermal technology uses heat to extract salt from water in various methods, such as multi-stage flash distillation, multi-effect distillation, and vapor compression distillation. Membrane technology passes saltwater through specially designed fiber “membranes” to eliminate salt compounds using methods such as electrodialysis, electrodialysis reversal, and reverse osmosis.
Although membrane designs have come a long way, the costs of implementation and maintenance are high, and other technology areas are being explored.
One example is the work by Dr. Thomas Hinkebein, a water-desalination expert who is associated with Sandia National Laboratories in Albuquerque, New Mexico. The NCBI has recognized his “roadmap” to implementing different desalination techniques, like concentration and reuse/recycle technologies, that may be more cost-effective than current technologies.
A key point is to keep the costs of desalination technologies comparable to those of existing wastewater management, so governments and industries can accept desalination as an economical option for gaining access to water.
Wise management of water resources, already a priority in most parts of the world, can only grow in importance in the coming decades. According to the World Bank, the world population, now around 8 billion people, is expected to rise to nearly 10 billion by 2050. With this predicted increase in population, individuals, communities, and governments must take a more significant role in managing their water sources.
*Patty Smith is a freelance writer in St. Petersburg, Florida, specializing in environmental issues, water concerns, and the effects of climate change on Florida's Gulf Coast.