Drinking water or potable water is water that is safe for ingestion, either when drunk directly in liquid form or consumed indirectly through food preparation. It is often supplied through taps, in which case it is also called tap water.
The amount of drinking water required to maintain good health varies, and depends on physical activity, age, health-related issues, and environmental conditions. This 2004 article focuses on the USA context and uses data collected from the US military. For those who work in a hot climate, up to a day may be required.
As many as two billion people lack safe drinking water. Unsafe water can carry disease and is a major cause of death and illness worldwide. Developing countries are most affected by unsafe drinking water.
Sources
Potable water is available in almost all populated areas of the world, although it may be expensive, and the supply may not always be sustainable. Sources where drinking water is commonly obtained include springs, hyporheic zones and aquifers (groundwater), from rainwater harvesting, surface water (from rivers, streams, glaciers), or desalinated seawater.
For these water sources to be consumed safely, they must receive adequate water treatment and meet drinking water quality standards.Hall, Ellen L.; Dietrich, Andrea M. (2000). "A Brief History of Drinking Water." Washington: American Water Works Association. Product No. OPF-0051634, Accessed 13 June 2012.
An experimental source is solar-powered atmospheric water generators.
Bottled water is a source of drinking water, especially when consumers perceive other sources to be unsafe. Although most bottled water is packaged tap water, springs are also used as sources for bottled water.
Supply
The most efficient and convenient way to transport potable water is through pipes. Plumbing can require significant capital investment. Some systems suffer high operating costs. The cost to replace the deteriorating water and sanitation infrastructure of industrialized countries may be as high as $200 billion a year. Leakage of untreated and treated water from pipes reduces access to water. Leakage rates of 50% are not uncommon in urban systems.United Nations. World Water Assessment Programme (2009). "Water in a Changing World: Facts and Figures." World Water Development Report 3. p. 58 Accessed 13 June 2012.
Tap water, delivered by domestic water systems refers to water piped to homes and delivered to a tap or spigot.
Quantity
Usage for general household use
In the United States, the typical water consumption per capita, at home, is of water per day.Mayer, P.W.; DeOreo, W.B.; Opitz, E.M.; Kiefer, J.C.; Davis, W.Y.; Dziegielewski, B.; & Nelson, J.O., 1999. Residential End Uses of Water. AWWARF and AWWA, Denver.William B. DeOreo, Peter Mayer, Benedykt Dziegielewski, Jack Kiefer. 2016. Residential End Uses of Water, Version 2. Water Research Foundation. Denver, Colorado. Of this, only 1% of the water provided by public water suppliers is for drinking and cooking.Joseph Cotruvo, Victor Kimm, Arden Calvert. "Drinking Water: A Half Century of Progress." EPA Alumni Association. 1 March 2016. Uses include (in decreasing order) toilets, washing machines, showers, baths, faucets, and leaks.
Usage for drinking
The recommended daily amount of drinking water for humans varies. It depends on activity, age, health, and environment. In the United States, the Adequate Intake for total water, based on median intakes, is per day for males older than 18, and per day for females over 18; it assumes about 80% from drink and 20% from food. The European Food Safety Authority recommends of total water per day for women and per day for men.
The common advice to drink 8 glasses () of plain water per day is not scientific; thirst is a better guide for how much water to drink than is a specific, fixed amount.H. Valtin, Drink at least eight glasses of water a day." Really? Is there scientific evidence for "8 × 8"? Am J Physiol Regul Integr Comp Physiol 283: R993-R1004, 2002. Americans aged 21 and older, on average, drink of drinking water a day, and 95% drink less than per day. Exercise and heat exposure cause loss of water and therefore may induce thirst and greater water intake. Active people in hot climates may need of water, or more, per day.
How much drinking water contributes to the intake of mineral nutrients is unclear. Inorganic minerals generally enter surface water and groundwater via stormwater runoff and through the ground. Water treatment also adds some minerals, such as calcium, zinc, manganese, phosphate, fluoride, and sodium compounds.World Health Organization (WHO). Geneva, Switzerland. Joyce Morrissey Donohue, Charles O. Abernathy, Peter Lassovszky, George Hallberg. "The contribution of drinking-water to total dietary intakes of selected trace mineral nutrients in the United States." Draft, August 2004. Water generated by the biochemical metabolism of nutrients provides a significant part of the daily water needs for some arthropods and desert animals, but provides only a small fraction of a human's necessary intake. There are trace elements in almost all potable water; some of these affect metabolism, such as sodium, potassium, and chloride, which are common in small amounts in most water. Other elements, such as fluoride, while beneficial in low concentrations, can cause dental and other problems at high levels.
Fluid balance is important to health. Profuse sweating can increase the need to replace electrolytes (salts). Water intoxication (the consumption of too much water too quickly) causes hyponatremia, which can cause death in minutes or hours. Water makes up about 60% of the body weight in men and 55% of weight in women. A baby is about 70% to 80%; old people are about 45% water.
Animals The qualitative and quantitative aspects of drinking water requirements on domesticated animals are examined within the context of animal husbandry. For example, a farmer might plan for per day for a dairy cow, a third of that for a horse, and a tenth of that for a hog.
However, relatively few studies have been focused on the drinking behavior of wild animals.
Quality
According to a 2017 World Health Organization report, safe drinking water is water that "does not represent any significant risk to health over a lifetime of consumption, including different sensitivities that may occur between life stages".
According to a report by UNICEF and UNESCO, Finland has the best drinking water quality in the world.
Parameters to monitor quality Parameters for drinking water quality typically fall within three categories: microbiological, chemical and physical.
Microbiological parameters include coliform bacteria, E. coli, and specific pathogenic species of bacteria (such as cholera-causing Vibrio cholerae), viruses and protozoan parasites. Originally, fecal contamination was determined with the presence of coliform bacteria, a convenient marker for a class of harmful fecal pathogens. The presence of fecal coliforms (like E. Coli) serves as an indication of contamination by sewage. Additional contaminants include protozoan oocysts such as Cryptosporidium sp., Giardia lamblia, Legionella, and viruses (enteric). Microbial pathogenic parameters are typically of greatest concern because of their immediate health risk.
Physical and chemical parameters include heavy metals, trace organic compounds, total suspended solids and turbidity. Chemical parameters tend to pose more of a chronic health risk through buildup of heavy metals although some components like nitrates/nitrites and arsenic can have a more immediate impact. Physical parameters affect the aesthetics and taste of the drinking water and may complicate the removal of microbial pathogens.
Pesticides are also potential drinking water contaminants of the category chemical contaminants. Pesticides may be present in drinking water in low concentrations, but the toxicity of the chemical and the extent of human exposure are factors that are used to determine the specific health risk.
Perfluorinated alkylated substances (PFAS) are a group of synthetic compounds used in a large variety of consumer products, such as food packaging, waterproof fabrics, carpeting and cookware. PFAS are known to persist in the environment and are commonly described as persistent organic pollutants. PFAS chemicals have been detected in blood, both humans and animals, worldwide, as well as in food products, water, air and soil. Animal testing studies with PFAS have shown effects on growth and development, and possibly effects on reproduction, thyroid, the immune system and liver. As of 2022 the health impacts of many PFAS compounds are not understood. Scientists are conducting research to determine the extent and severity of impacts from PFAS on human health. PFAS have been widely detected in drinking water worldwide and regulations have been developed, or are under development, in many countries. The U.S. Environmental Protection Agency (EPA) has published laboratory test methods for PFAS compounds.
Drinking water quality standards
Health issues due to low quality
The World Health Organization considers access to safe drinking-water a basic human right. Contaminated water is estimated to result in more than half a million deaths per year. More people die from unsafe water than from war, then-U.N. secretary-general Ban Ki-moon said in 2010. Contaminated water together with the lack of sanitation was estimated to cause about one percent of disability adjusted life years worldwide in 2010. According to the WHO, the most common diseases linked with poor water quality are cholera, diarrhea, dysentery, hepatitis A, typhoid, and polio.
One of the main causes for contaminated drinking water in developing countries is lack of sanitation and poor hygiene. For this reason, the quantification of the burden of disease from consuming contaminated drinking water usually looks at water, sanitation and hygiene aspects together. The acronym for this is WASH – standing for water, sanitation and hygiene.
Diarrhea, malnutrition and stunting
Consumption of contaminated groundwater
Sixty million people are estimated to have been poisoned by well water contaminated by excessive fluoride, which dissolved from granite rocks. The effects are particularly evident in the bone deformations of children. Similar or larger problems are anticipated in other countries including China, Uzbekistan, and Ethiopia. Although helpful for dental health in low dosage, fluoride in large amounts interferes with bone formation.
Long-term consumption of water with high fluoride concentration (> 1.5 ppm F) can have serious undesirable consequences such as dental fluorosis, enamel mottle and skeletal fluorosis, bone deformities in children. Fluorosis severity depends on how much fluoride is present in the water, as well as people's diet and physical activity. Defluoridation methods include membrane-based methods, precipitation, absorption, and electrocoagulation.
Natural arsenic contamination of groundwater is a global threat with 140 million people affected in 70 countries globally.
Examples of poor drinking water quality incidents
Some examples of water quality problems with drinking water supplies include: Text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License In 1854, a cholera outbreak in London's Soho district was identified by John Snow as originating from contaminated water from the Broad Street pump. This was a founding event of the science of epidemiology. Contamination of groundwater with arsenic in Bangladesh; the largest-scale mass poisoning of a population (began in the 1970s–1980s, officially recognized in 1993). Hinkley groundwater contamination (Chromium-6 contamination of private groundwater wells in Hinkley, California, United States (settled in 1996).