Water conservation

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United States 1960 postal stamp advocating water conservation. Water-conservation-stamp-1960.jpg
United States 1960 postal stamp advocating water conservation.

Water conservation includes all the policies, strategies and activities to sustainably manage the natural resource of fresh water, to protect the hydrosphere, and to meet the current and future human demand. Population, household size and growth and affluence all affect how much water is used. Factors such as climate change have increased pressures on natural water resources especially in manufacturing and agricultural irrigation. [1] Many countries have already implemented policies aimed at water conservation, with much success. [2]

Contents

The goals of water conservation efforts include:

Strategies

The key activities to conserve water are as follows:

One of the strategies in water conservation is rain water harvesting. [7] Digging ponds, lakes, canals, expanding the water reservoir, and installing rain water catching ducts and filtration systems on homes are different methods of harvesting rain water. Many people in many countries keep clean containers so they can boil it and drink it, which is useful to supply water to the needy. [7] Harvested and filtered rain water can be used for toilets, home gardening, lawn irrigation, and small scale agriculture. [7]

Another strategy in water conservation is protecting groundwater resources. When precipitation occurs, some infiltrates the soil and goes underground. [8] Water in this saturation zone is called groundwater. [8] Contamination of groundwater causes the groundwater water supply to not be able to be used as a resource of fresh drinking water and the natural regeneration of contaminated groundwater can take years to replenish. [9] Some examples of potential sources of groundwater contamination include storage tanks, septic systems, uncontrolled hazardous waste, landfills, atmospheric contaminants, chemicals, and road salts. [9] Contamination of groundwater decreases the replenishment of available freshwater so taking preventative measures by protecting groundwater resources from contamination is an important aspect of water conservation. [7]

An additional strategy to water conservation is practicing sustainable methods of utilizing groundwater resources. [7] Groundwater flows due to gravity and eventually discharges into streams. [8] Excess pumping of groundwater leads to a decrease in groundwater levels and if continued it can exhaust the resource. [7] Ground and surface waters are connected and overuse of groundwater can reduce and, in extreme examples, diminish the water supply of lakes, rivers, and streams. [9] In coastal regions, over pumping groundwater can increase saltwater intrusion which results in the contamination of groundwater water supply. [9] Sustainable use of groundwater is essential in water conservation.

A fundamental component to water conservation strategy is communication and education outreach of different water programs. [10] Developing communication that educates science to land managers, policy makers, farmers, and the general public is another important strategy utilized in water conservation. [10] Communication of the science of how water systems work is an important aspect when creating a management plan to conserve that system and is often used for ensuring the right management plan to be put into action. [10]

"Water Conservation Day" is celebrated on 22nd of March.[ citation needed ]

Social solutions

Drip irrigation system in New Mexico VineyardDrip.JPG
Drip irrigation system in New Mexico

Water conservation programs involved in social solutions are typically initiated at the local level, by either municipal water utilities or regional governments. Common strategies include public outreach campaigns, [11] tiered water rates (charging progressively higher prices as water use increases), or restrictions on outdoor water use such as lawn watering and car washing. [12] Cities in dry climates often require or encourage the installation of xeriscaping or natural landscaping in new homes to reduce outdoor water usage. [13] Most urban outdoor water use in California is residential, [14] illustrating a reason for outreach to households as well as businesses.

One fundamental conservation goal is universal metering. The prevalence of residential water metering varies significantly worldwide. Recent studies have estimated that water supplies are metered in less than 30% of UK households, [15] and about 61% of urban Canadian homes (as of 2001). [16] Although individual water meters have often been considered impractical in homes with private wells or in multifamily buildings, the US Environmental Protection Agency estimates that metering alone can reduce consumption by 20 to 40 percent. [17] In addition to raising consumer awareness of their water use, metering is also an important way to identify and localize water leakage. Water metering would benefit society, in the long run, it is proven that water metering increases the efficiency of the entire water system, as well as help unnecessary expenses for individuals for years to come. One would be unable to waste water unless they are willing to pay the extra charges, this way the water department would be able to monitor water usage by the public, domestic and manufacturing services.

Some researchers have suggested that water conservation efforts should be primarily directed at farmers, in light of the fact that crop irrigation accounts for 70% of the world's fresh water use. [18] The agricultural sector of most countries is important both economically and politically, and water subsidies are common. Conservation advocates have urged removal of all subsidies to force farmers to grow more water-efficient crops and adopt less wasteful irrigation techniques.[ citation needed ]

New technology poses a few new options for consumers, features such as full flush and half flush when using a toilet are trying to make a difference in water consumption and waste. It is also possible to use/"pollute" the water in stages (keeping use in flush toilets for last), hereby allowing more use of the water for various tasks within a same cycle (before it needs to be purified again, which can also be done in-situ). Earthships often use such a setup.

Also available are modern shower heads that help reduce wasting water: Old shower heads are said to use 5-10 gallons per minute, while new fixtures available use 2.5 gallons per minute and offer equal water coverage. [19] Another method is to recycle the water of the shower directly, by means a semi-closed system which features a pump and filter. Such a setup (called a "water recycling shower") has also been employed at the VIRTUe LINQ house. Besides recycling water, it also reuses the heat of the water (which would otherwise be lost). [20] [21]

Household applications

The Home Water Works website contains useful information on household water conservation. [22] Contrary to the popular view that the most effective way to save water is to curtail water-using behavior (e.g., by taking shorter showers), [23] experts suggest the most efficient way is replacing toilets and retrofitting washers; as demonstrated by two household end use logging studies in the US. [24] [25]

Water-saving technology for the home includes:

Commercial applications

Many water-saving devices (such as low-flush toilets) that are useful in homes can also be useful for business water saving. Other water-saving technology for businesses includes:

Agricultural applications

Overhead irrigation, center pivot design PivotIrrigationOnCotton.jpg
Overhead irrigation, center pivot design

Water is a very important part in irrigation. Plants always take a lot of ground water thus ground water should be replenished. For crop irrigation, optimal water efficiency means minimizing losses due to evaporation, runoff or subsurface drainage while maximizing production. An evaporation pan in combination with specific crop correction factors can be used to determine how much water is needed to satisfy plant requirements. Flood irrigation, the oldest and most common type, is often very uneven in distribution, as parts of a field may receive excess water in order to deliver sufficient quantities to other parts. Overhead irrigation, using center-pivot or lateral-moving sprinklers, has the potential for a much more equal and controlled distribution pattern. Drip irrigation is the most expensive and least-used type, but offers the ability to deliver water to plant roots with minimal losses. However, drip irrigation is increasingly affordable, especially for the home gardener and in light of rising water rates. Using drip irrigation methods can save up to 30,000 gallons of water per year when replacing irrigation systems that spray in all directions. [26] There are also cheap effective methods similar to drip irrigation such as the use of soaking hoses that can even be submerged in the growing medium to eliminate evaporation.

As changing irrigation systems can be a costly undertaking, conservation efforts often concentrate on maximizing the efficiency of the existing system. This may include chiselling compacted soils, creating furrow dikes to prevent runoff, and using soil moisture and rainfall sensors to optimize irrigation schedules. [17] Usually large gains in efficiency are possible through measurement and more effective management of the existing irrigation system. The 2011 UNEP Green Economy Report notes that "[i]mproved soil organic matter from the use of green manures, mulching, and recycling of crop residues and animal manure increases the water holding capacity of soils and their ability to absorb water during torrential rains", [27] which is a way to optimize the use of rainfall and irrigation during dry periods in the season.

Water reuse

Water shortage has become an increasingly difficult problem to manage. More than 40% of the world's population live in a region where the demand for water exceeds its supply. The imbalance between supply and demand, along with persisting issues such as climate change and population growth, has made water reuse a necessary method for conserving water. [28] There are a variety of methods used in the treatment of waste water to ensure that it is safe to use for irrigation of food crops and/or drinking water.

Seawater desalination requires more energy than the desalination of fresh water. Despite this, many seawater desalination plants have been built in response to water shortages around the world. This makes it necessary to evaluate the impacts of seawater desalination and to find ways to improve desalination technology. Current research involves the use of experiments to determine the most effective and least energy intensive methods of desalination. [29] [30]

Sand filtration is another method used to treat water. Recent studies show that sand filtration needs further improvements, but it is approaching optimization with its effectiveness at removing pathogens from water. [31] [32] Sand filtration is very effective at removing protozoa and bacteria, but struggles with removing viruses. [33] Large-scale sand filtration facilities also require large surface areas to accommodate them.

The removal of pathogens from recycled water is of high priority because wastewater always contains pathogens capable of infecting humans. The levels of pathogenic viruses have to be reduced to a certain level in order for recycled water to not pose a threat to human populations. Further research is necessary to determine more accurate methods of assessing the level of pathogenic viruses in treated wastewater. [34]

Wasting of water

Leaking garden hose bib Leaking garden hose bib.jpg
Leaking garden hose bib

Wasting of water (also called "water waste" in the US) is the flip side of water conservation and, in household applications, it means causing or permitting discharge of water without any practical purpose. Inefficient water use is also considered wasteful. By EPA estimate, household leaks in the US can waste approximately 900 billion gallons (3.4 billion cubic meters) of water annually nationwide. [35] Generally, water management agencies are reluctant or unwilling to give a concrete definition to the somewhat fuzzy concept of water waste. [36]

However, definition of water waste is often given in local drought emergency ordinances. One example refers to any acts or omissions, whether willful or negligent, that are “causing or permitting water to leak, discharge, flow or run to waste into any gutter, sanitary sewer, watercourse or public or private storm drain, or to any adjacent property, from any tap, hose, faucet, pipe, sprinkler, pond, pool, waterway, fountain or nozzle.”. [37] In this example, the city code also clarifies that “in the case of washing, “discharge,” “flow” or “run to waste” means that water in excess of that necessary to wash, wet or clean the dirty or dusty object, such as an automobile, sidewalk, or parking area, flows to waste.

Water utilities (and other media sources) often provide listings of wasteful water-use practices and prohibitions of wasteful uses. Examples include utilities in San Antonio, Texas. [38] Las Vegas, Nevada, [39] California Water Service company in California, [40] and City of San Diego, California. [41] The City of Palo Alto in California enforces permanent water use restrictions on wasteful practices such as leaks, runoff, irrigating during and immediately after rainfall, and use of potable water when non-potable water is available. [42] Similar restrictions are in effect in the State of Victoria, Australia. [43] Temporary water use bans (also known as "hosepipe bans") are used in England, Scotland, Wales and Northern Ireland. [44]

Strictly speaking, water that is discharged into the sewer, or directly to the environment is not wasted or lost. It remains within the hydrologic cycle and returns to the land surface and surface water bodies as precipitation. However, in many cases, the source of the water is at a significant distance from the return point and may be in a different catchment. The separation between extraction point and return point can represent significant environmental degradation in the watercourse and riparian strip. What is "wasted" is the community's supply of water that was captured, stored, transported and treated to drinking quality standards. Efficient use of water saves the expense of water supply provision and leaves more fresh water in lakes, rivers and aquifers for other users and also for supporting ecosystems.

A concept that is closely related to water wasting is "water-use efficiency." Water use is considered inefficient if the same purpose of its use can be accomplished with less water. Technical efficiency derives from engineering practice where it is typically used to describe the ratio of output to input and is useful in comparing various products and processes. [45] For example, one showerhead would be considered more efficient than another if it could accomplish the same purpose (i.e., of showering) by using less water or other inputs (e.g., lower water pressure). Urinals are more efficient than toilet stalls in public restrooms for men or boys in situations where the user only needs to urinate; and although this is a natural function, urinals offer considerably less privacy. The technical efficiency concept is not useful in making decisions of investing money (or resources) in water conservation measures unless the inputs and outputs are measured in value terms. This expression of efficiency is referred to as economic efficiency and is incorporated into the concept of water conservation.

See also

Related Research Articles

Brine A highly concentrated solution of a salt in water

Brine is a high-concentration solution of salt (NaCl) in water (H2O). In different contexts, brine may refer to salt solutions ranging from about 3.5% (a typical concentration of seawater, on the lower end of solutions used for brining foods) up to about 26% (a typical saturated solution, depending on temperature). Lower levels of concentration are called by different names: fresh water, brackish water, and saline water.

Desalination Removal of salts and minerals from a substance

Desalination is a process that takes away mineral components from saline water. More generally, desalination refers to the removal of salts and minerals from a target substance, as in soil desalination, which is an issue for agriculture.

Greywater A type of wastewater generated in households without toilet wastewater

Grey water or sullage is all the wastewater generated in households or office buildings from streams without fecal contamination, i.e. all streams except for the wastewater from toilets. Sources of grey water include sinks, showers, baths, washing machines or dishwashers. As grey water contains fewer pathogens than domestic wastewater, it is generally safer to handle and easier to treat and reuse onsite for toilet flushing, landscape or crop irrigation, and other non-potable uses.

Wastewater Water that has been contaminated by human use

Wastewater is any water that has been contaminated by human use. Wastewater is "used water from any combination of domestic, industrial, commercial or agricultural activities, surface runoff or stormwater, and any sewer inflow or sewer infiltration". Therefore, wastewater is a byproduct of domestic, industrial, commercial or agricultural activities. The characteristics of wastewater vary depending on the source. Types of wastewater include: domestic wastewater from households, municipal wastewater from communities and industrial wastewater. Wastewater can contain physical, chemical and biological pollutants.

Sustainable living describes a lifestyle that attempts to reduce an individual's or society's use of the Earth's natural resources, and one's personal resources. It is often called as "earth harmony living" or "net zero living". Its practitioners often attempt to reduce their ecological footprint by altering their methods of transportation, energy consumption, and/or diet. Its proponents aim to conduct their lives in ways that are consistent with sustainability, naturally balanced, and respectful of humanity's symbiotic relationship with the Earth's natural ecology. The practice and general philosophy of ecological living closely follows the overall principles of sustainable development.

Water treatment Process that improves the quality of water

Water treatment is any process that improves the quality of water to make it more acceptable for a specific end-use. The end use may be drinking, industrial water supply, irrigation, river flow maintenance, water recreation or many other uses, including being safely returned to the environment. Water treatment removes contaminants and undesirable components, or reduces their concentration so that the water becomes fit for its desired end-use. This treatment is crucial to human health and allows humans to benefit from both drinking and irrigation use.

Reclaimed water Converting wastewater into water that can be reused for other purposes

Reclaimed or recycled water is the process of converting wastewater into water that can be reused for other purposes. Reuse may include irrigation of gardens and agricultural fields or replenishing surface water and groundwater. Reused water may also be directed toward fulfilling certain needs in residences, businesses, and industry, and could even be treated to reach drinking water standards. This last option is called either "direct potable reuse" or "indirect potable" reuse, depending on the approach used.

Water supply and sanitation in Hong Kong is characterized by water import, reservoirs and treatment infrastructure. Though multiple measures were made throughout its history, providing an adequate water supply for Hong Kong has met with numerous challenges because the region has few natural lakes and rivers, inadequate groundwater sources, a high population density, and extreme seasonable variations in rainfall. Thus nearly 80 percent of water demand is met by importing water from mainland China, based on a longstanding contract. In addition, freshwater demand is curtailed by the use of seawater for toilet flushing, using a separate distribution system. Hong Kong also utilize the usage of reservoirs and water treatment plants to maintain its source of clean water through times.

Issues that affect drinking water supply and sanitation in the United States include water scarcity, pollution, a backlog of investment, concerns about the affordability of water for the poorest, and a rapidly retiring workforce. Increased variability and intensity of rainfall as a result of climate change is expected to produce both more severe droughts and flooding, with potentially serious consequences for water supply and for pollution from combined sewer overflows. Droughts are likely to particularly affect the 66 percent of Americans whose communities depend on surface water. As for drinking water quality, there are concerns about disinfection by-products, lead, perchlorates, PFAS and pharmaceutical substances, but generally drinking water quality in the U.S. is good.

Water efficiency is reducing water wastage by measuring the amount of water required for a particular purpose and the amount of water used or delivered. Water efficiency differs from water conservation in that it focuses on reducing waste, not restricting use. Solutions for water efficiency focus not only on reducing the amount of potable water used, but also on reducing the use of non-potable water where appropriate. It also emphasises the influence consumers can have in water efficiency by making small behavioural changes to reduce water wastage and by choosing more water efficient products.

Reverse osmosis (RO) is a water purification process that uses a partially permeable membrane to remove ions, unwanted molecules and larger particles from drinking water. In reverse osmosis, an applied pressure is used to overcome osmotic pressure, a colligative property that is driven by chemical potential differences of the solvent, a thermodynamic parameter. Reverse osmosis can remove many types of dissolved and suspended chemical species as well as biological ones (principally bacteria) from water, and is used in both industrial processes and the production of potable water. The result is that the solute is retained on the pressurized side of the membrane and the pure solvent is allowed to pass to the other side. To be "selective", this membrane should not allow large molecules or ions through the pores (holes), but should allow smaller components of the solution (such as solvent molecules, i.e., water, H2O) to pass freely.

Water supply and sanitation in Israel are intricately linked to the historical development of Israel. Because rain falls only in the winter, and largely in the northern part of the country, irrigation and water engineering are considered vital to the country's economic survival and growth. Large scale projects to desalinate seawater, direct water from rivers and reservoirs in the north, make optimal use of groundwater, and reclaim flood overflow and sewage have been undertaken. Among them is the National Water Carrier, carrying water from the country's biggest freshwater lake, the Sea of Galilee, to the northern Negev desert through channels, pipes and tunnels. Israel's water demand today outstrips available conventional water resources. Thus, in an average year, Israel relies for about half of its water supply on unconventional water resources, including reclaimed water and desalination. A particularly long drought in 1998–2002 had prompted the government to promote large-scale seawater desalination.

Integrated urban water management

Integrated urban water management (IUWM) is a philosophy of varying definitions and interpretations. According to the authors of the book entitled, "Integrated Urban Water Management: Humid Tropics", IUWM is described as the practice of managing freshwater, wastewater, and storm water as components of a basin-wide management plan. It builds on existing water supply and sanitation considerations within an urban settlement by incorporating urban water management within the scope of the entire river basin. One of the early champions of IUWM, SWITCH is a research program funded by the European Union and seeks to shift urban water management away from ad hoc solutions to a more integrated approach. IUWM within an urban water system can also be conducted by performance assessment of any new intervention strategies by developing a holistic approach which encompasses various system elements and criteria including sustainability type ones in which integration of water system components including water supply, waste water and storm water subsystems would be advantageous. Simulation of metabolism type flows in urban water system can also be useful for analysing processes in urban water cycle of IUWM.

Sewer dosing unit

A sewer dosing unit (SDU) is a plumbing device to allow effective sewage disposal with low liquid-flow rates. With a global emphasis on water saving, many new buildings and renovations are seeing the installation of water saving fixtures such as low flow shower heads and low flush toilets. With the decrease in wastewater flows problems are arising from waste solids not being carried completely to the main sewers, often causing blockages.

The three cities of Abu Dhabi Emirate within the United Arab Emirates – the coastal city Abu Dhabi itself as well as the inland oases Al Ain and Liwa – receive their drinking water supply entirely from desalinated seawater.

Resource recovery is using wastes as an input material to create valuable products as new outputs. The aim is to reduce the amount of waste generated, thereby reducing the need for landfill space, and optimising the values created from waste. Resource recovery delays the need to use raw materials in the manufacturing process. Materials found in municipal solid waste, construction and demolition waste, commercial waste and industrial wastes can be used to recover resources for the manufacturing of new materials and products. Plastic, paper, aluminium, glass and metal are examples of where value can be found in waste.

Beijing, the capital of China, is characterized by intense water scarcity during the long dry season as well as heavy flooding during the brief wet season. Beijing is one of the most water-scarce cities in the world. Total water use is 3.6 billion cubic meters, compared to renewable fresh water resources of about 3 billion cubic meters. The difference is made up by the overexploitation of groundwater. Two-thirds of the water supply comes from groundwater, one third from surface water. Average rainfall has substantially declined since the 1950s. Furthermore, one of the two main rivers supplying the city, the Yongding River, had to be abandoned as a source of drinking water because of pollution. Water savings in industry and agriculture have compensated for these losses and freed up water for residential uses.

Rainwater harvesting in Canada

Rainwater harvesting is becoming a procedure that many Canadians are incorporating into their daily lives, although data does not give exact figures for implementation. Rainwater can be used for a number of purposes including stormwater reduction, irrigation, laundry and portable toilets. In addition to low costs, rainwater harvesting is useful for landscape irrigation.

Water reuse in California

As a heavily populated state in the drought-prone arid west, water reuse in California—the use of reclaimed water for beneficial use—has developed as an integral part of water in California's story enabling both the economy and population to grow. Reclaimed water is treated wastewater that comes from homes and businesses, such as sink water, shower water, and even toilet water; this includes everything dumped down these wastewater drains from laundry soap to bleach to oil to human waste. Wastewater can divided into greywater and blackwater, with the first being defined as water that had been used for laundry, bathing, sink washing, and dishwaters. Blackwater, on the other hand, is defined as sewage that includes feces from toilets. Due to the low amounts of physical pollutants in greywater, most of its contaminants are dissolved organic matter, which can be physically filtered and cleaned through various membranes, as well as through biological treatment methods.

Residential water use in the U.S. and Canada

Residential water use includes all indoor and outdoor uses of drinking quality water at single-family and multifamily dwellings. These uses include a number of defined purposes such as flushing toilets, washing clothes and dishes, showering and bathing, drinking, food preparation, watering lawns and gardens, and maintaining swimming pools. Some of these end uses are detectable while others are more difficult to gauge.

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Further reading