Water pollution

A practical definition of water pollution is: "Water pollution is the addition of substances or energy forms that directly or indirectly alter the nature of the water body in such a manner that negatively affects its legitimate uses." Water is usually considered polluted when it is contaminated by anthropogenic substances. This means that it either cannot be used for certain purposes, such as for drinking, or its ability to support its biotic communities, such as fish, has changed significantly. == Contaminants ==

Contaminants with an origin in sewage The following compounds can all reach water bodies via raw sewage or even treated sewage discharges: • Various chemical compounds found in personal hygiene and cosmetic products. • Disinfection by-products found in chemically disinfected drinking water (whilst these chemicals can be a pollutant in the water distribution network, they are fairly volatile and therefore not usually found in environmental waters). • Hormones (from animal husbandry and residue from human hormonal contraception methods) and synthetic materials such as phthalates that mimic hormones in their action. These can have adverse impacts even at very low concentrations on the natural biota and potentially on humans if the water is treated and utilized for drinking water. • Insecticides and herbicides, often from agricultural runoff. • Pathogens like Hepatovirus A (HAV may be present in treated wastewater outflows and receiving water bodies but is largely removed during further treatment of drinking water) Inadequately treated wastewater can convey nutrients, pathogens, heterogenous suspended solids and organic fecal matter. Some microorganisms sometimes found in contaminated surface waters that have caused human health problems include Burkholderia pseudomallei, Cryptosporidium parvum, Giardia lamblia, Salmonella, norovirus and other viruses, and parasitic worms including the Schistosoma type. High levels of pathogens in water bodies can be caused by human feces (due to open defecation), sewage, blackwater, or manure that has found its way into the water. This can be due to a lack of adequate sanitation procedures or poorly functioning on-site sanitation systems (septic tanks, pit latrines), sewage treatment plants without disinfection steps, sanitary sewer overflows and combined sewer overflows (CSOs) during storm events and intensive agriculture (poorly managed livestock operations). Organic compounds Organic substances that enter water bodies are often toxic. • Petroleum hydrocarbons, including fuels (gasoline, diesel fuel, jet fuels, and fuel oil) and lubricants (motor oil), and fuel combustion byproducts, from oil spills or storm water runoff • Volatile organic compounds, such as improperly stored industrial solvents. Problematic species are organochlorides such as polychlorinated biphenyl (PCBs) and trichloroethylene, a common solvent. Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants. Inorganic contaminants is an industrial waste that is dangerously alkaline and can lead to water pollution if not managed appropriately (photo from Stade, Germany). Inorganic water pollutants include: • Ammonia from food processing waste • Heavy metals from motor vehicles (via urban storm water runoff) and acid mine drainage • Nitrates and phosphates, from sewage and agriculture (see nutrient pollution) • Silt (sediment) in runoff from construction sites or sewage, logging, slash and burn practices land clearing sites • Salt: Freshwater salinization is the process of salty runoff contaminating freshwater ecosystems. Human-induced salinization is termed as secondary salinization, with the use of de-icing road salts as the most common form of runoff. Pharmaceutical pollutants • Environmental persistent pharmaceutical pollutants, which can include various pharmaceutical drugs and their metabolites (see also drug pollution), such as antidepressant drugs, antibiotics or the contraceptive pill. • Metabolites of illicit drugs (see also wastewater epidemiology), for example methamphetamine and ecstasy. Solid waste and plastics , Canada Solid waste can enter water bodies through untreated sewage, combined sewer overflows, urban runoff, and people discarding garbage into the environment. Wind can also carry municipal solid waste from landfills, resulting in macroscopic pollution, where large visible items pollute the water, as well as microplastic pollution that is not directly visible. The terms marine debris and marine plastic pollution are used in the context of pollution of oceans. Microplastics persist in the environment at high levels, particularly in aquatic and marine ecosystems, where they cause water pollution. 35% of all ocean microplastics come from textiles/clothing, primarily due to the erosion of polyester, acrylic, or nylon-based clothing, often during the washing process. The main ways in which microplastics are transported from land to sea are via stormwater, untreated sewage and wind. The most common sources of microplastics are synthetic fabrics, tyres, and urban dust. These three sources together account for over 80% of all microplastic contamination. == Types of surface water pollution ==

Surface water pollution includes pollution of rivers, lakes and oceans. A subset of surface water pollution is marine pollution which affects the oceans. Nutrient pollution refers to contamination by excessive inputs of nutrients. As of 2017, an estimated 4.5 billion people globally did not have access to safely managed sanitation, according to the Joint Monitoring Programme for Water Supply and Sanitation. Lack of access to sanitation is a serious issue which often leads to water pollution. For example, open defecation can result in human feces being moved from the ground into surface waters during rain events or floods. Simple pit latrines may also flood during heavy rainfall. As of 2022, Europe and Central Asia account for around 16% of the global discharge of microplastics into the seas. Although the management of plastic waste and its recycling is improving globally, the absolute amount of plastic pollution continues to increase unabated due to the large quantity of plastic in circulation. Even if sea plastic pollution were to stop entirely, microplastic contamination of the surface ocean would be projected to continue to increase. == Groundwater pollution ==

In many parts of the world, groundwater pollution endangers the well-being of people and ecosystems. One quarter of the world's population relies on groundwater for drinking water, yet concentrated recharge is known to carry short-lived contaminants into carbonate aquifers, endangering the purity of these waters. == Pollution from point sources ==

Point source water pollution refers to contaminants entering a waterway from a single, identifiable source, such as a pipe or ditch. Examples of sources in this category include discharges from sewage treatment plants, factories, and city storm drains. The U.S. Clean Water Act (CWA) defines point source for regulatory enforcement purposes (see United States regulation of point source water pollution). The CWA definition of point source was amended in 1987 to include municipal storm sewer systems, as well as industrial storm water, such as from construction sites. Sewage Sewage typically consists of 99.9% water and 0.1% solids. Sewage contributes many classes of nutrients that lead to Eutrophication. It is a major source of phosphate for example. Sewage is often contaminated with diverse compounds found in personal hygiene, cosmetics, pharmaceutical drugs (see also drug pollution), and their metabolites Industrial processes that use water also produce wastewater. This is known as industrial wastewater. In the US, for instance, power plants, petroleum refineries, iron and steel mills, pulp and paper mills, and food processing industries are the main industrial consumers of water, using over 60% of the total. • Microplastics such as polyethylene and polypropylene beads, polyester and polyamide • Thermal pollution from power stations and industrial manufacturers • Radionuclides from uranium mining, processing nuclear fuel, operating nuclear reactors, or disposal of radioactive waste. • Some industrial discharges include persistent organic pollutants such as per- and polyfluoroalkyl substances (PFAS). Oil spills == Pollution from nonpoint sources ==

Agriculture Agriculture is a major contributor to water pollution from nonpoint sources. The use of fertilizers as well as surface runoff from farm fields, pastures and feedlots leads to nutrient pollution. In addition to plant-focused agriculture, fish-farming is also a source of pollution. Additionally, agricultural runoff often contains high levels of pesticides. Acid rain is caused by the emission of sulfur dioxide and nitrogen oxide, which react with the water molecules in the atmosphere to produce acids. Some governments have made efforts since the 1970s to reduce the release of sulfur dioxide and nitrogen oxide into the atmosphere. The main sources of sulfur and nitrogen compounds that result in acid rain are anthropogenic, but nitrogen oxides can also be produced naturally by lightning strikes and sulphur dioxide is produced by volcanic eruptions. Acid rain can have harmful effects on plants, aquatic ecosystems and infrastructure. Carbon dioxide concentrations in the atmosphere have increased since the 1850s due anthropogenic influences (emissions of greenhouse gases). == Sampling, measurements, analysis ==

preparing water autosamplers Water pollution may be analysed through several broad categories of methods: physical, chemical and biological. Some methods may be conducted in situ, without sampling, such as temperature. Others involve collection of samples, followed by specialized analytical tests in the laboratory. Standardized, validated analytical test methods, for water and wastewater samples have been published. Common physical tests of water include temperature, Specific conductance or electrical conductance (EC) or conductivity, solids concentrations (e.g., total suspended solids (TSS)) and turbidity. Water samples may be examined using analytical chemistry methods. Many published test methods are available for both organic and inorganic compounds. Frequently used parameters that are quantified are pH, BOD, chemical oxygen demand (COD), Biological testing involves the use of plant, animal or microbial indicators to monitor the health of an aquatic ecosystem. They are any biological species or group of species whose function, population, or status can reveal what degree of ecosystem or environmental integrity is present. One example of a group of bio-indicators are the copepods and other small water crustaceans that are present in many water bodies. Such organisms can be monitored for changes (biochemical, physiological, or behavioral) that may indicate a problem within their ecosystem. == Impacts ==

, resulting from nitrogen pollution and eutrophication, is a common cause of fish kills. Ecosystems Water pollution is a major global environmental problem because it can degrade all aquatic ecosystems, including freshwater, coastal, and ocean waters. The specific contaminants that lead to water pollution include a wide range of chemicals, pathogens, and physical changes such as elevated temperature. While many of the chemicals and substances that are regulated may be naturally occurring (calcium, sodium, iron, manganese, etc.) the concentration usually determines what is a natural component of water and what is a contaminant. High concentrations of naturally occurring substances can have negative impacts on aquatic flora and fauna. Oxygen-depleting substances may be natural materials such as plant matter (e.g. leaves and grass) as well as human-made chemicals. Other natural and anthropogenic substances may cause turbidity (cloudiness) which blocks light and disrupts plant growth, and clogs the gills of some fish species. collected from pit latrines is dumped into a river at the Korogocho slum in Nairobi, Kenya Public health and waterborne diseases A study published in 2017 stated that "polluted water spread gastrointestinal diseases and parasitic infections and killed 1.8 million people" (these are also referred to as waterborne diseases). Persistent exposure to pollutants through water are environmental health hazards, which can increase the likelihood for one to develop cancer or other diseases. Eutrophication from nitrogen pollution Nitrogen pollution can cause eutrophication, especially in lakes. Eutrophication is an increase in the concentration of chemical nutrients in an ecosystem to an extent that increases the primary productivity of the ecosystem. Subsequent negative environmental effects such as anoxia (oxygen depletion) and severe reductions in water quality may occur. == Prevalence ==

Water pollution is a problem in developing countries as well as in developed countries. By country For example, water pollution in India and China is widespread. About 90 percent of the water in the cities of China is polluted. ==Control and reduction==

, Washington, D.C., United States. Seen in the distance are the sludge digester building and thermal hydrolysis reactors. Pollution control philosophy Mandatory regulations are one aspect of environmental protection, but they are only part of the solution. Other important tools for controlling pollution include environmental education, economic instruments, market forces and stricter enforcement. Standards can be "precise" (for a defined quantifiable minimum or maximum value for a pollutant), or "imprecise" which would require the use of Best available technology (BAT) or Best practicable environmental option (BPEO). Market-based economic instruments for pollution control can include charges, subsidies, deposit or refund schemes, the creation of a market in pollution credits, and enforcement incentives. Moving towards a holistic approach in chemical pollution control combines the following approaches: Integrated control measures, trans-boundary considerations, complementary and supplementary control measures, life-cycle considerations, the impacts of chemical mixtures. or in onsite sewage facilities and septic tanks. For example, waste stabilization ponds can be a low cost treatment option for sewage. UV light (sunlight) can be used to degrade some pollutants in waste stabilization ponds (sewage lagoons). The use of safely managed sanitation services would prevent water pollution caused by lack of access to sanitation. Some plants have additional systems to remove nutrients and pathogens. While such advanced treatment techniques will undoubtedly reduce the discharges of micropollutants, they can also result in large financial costs, as well as environmentally undesirable increases in energy consumption and greenhouse gas emissions. Sewer overflows during storm events can be addressed by timely maintenance and upgrades of the sewerage system. In the US, cities with large combined systems have not pursued system-wide separation projects due to the high cost, but have implemented partial separation projects and green infrastructure approaches. In some cases municipalities have installed additional CSO storage facilities or expanded sewage treatment capacity. Industrial wastewater treatment Agricultural wastewater treatment Management of erosion and sediment control installed on a construction site Sediment from construction sites can be managed by installation of erosion controls, such as mulching and hydroseeding, and sediment controls, such as sediment basins and silt fences. Discharge of toxic chemicals such as motor fuels and concrete washout can be prevented by use of spill prevention and control plans, and specially designed containers (e.g. for concrete washout) and structures such as overflow controls and diversion berms. Erosion caused by deforestation and changes in hydrology (soil loss due to water runoff) also results in loss of sediment and, potentially, water pollution. Control of urban runoff (storm water) in 2020. A water body is classified as "good" quality if at least 80% of monitoring values meet target quality levels, see also SDG 6, Indicator 6.3.2. Legislation Philippines In the Philippines, Republic Act 9275, otherwise known as the Philippine Clean Water Act of 2004, is the governing law on wastewater management. It states that it is the country's policy to protect, preserve and revive the quality of its fresh, brackish and marine waters, for which wastewater management plays a particular role. The study gained media attention, with comments from the UKs leading health professionals, including Sir Chris Whitty. Outlining 15 recommendations for various UK bodies to dramatically reduce public health risks by increasing the water quality in its waterways, such as rivers and lakes. After the release of the report, The Guardian newspaper interviewed Whitty, who stated that improving water quality and sewage treatment should be a high level of importance and a "public health priority". He compared it to eradicating cholera in the 19th century in the country following improvements to the sewage treatment network. The study also identified that low water flows in rivers saw high concentration levels of sewage, as well as times of flooding or heavy rainfall. While heavy rainfall had always been associated with sewage overflows into streams and rivers, the British media went as far to warn parents of the dangers of paddling in shallow rivers during warm weather. Whitty's comments came after the study revealed that the UK was experiencing a growth in the number of people that were using coastal and inland waters recreationally. This could be connected to a growing interest in activities such as open water swimming or other water sports. Despite this growth in recreation, poor water quality meant some were becoming unwell during events. Most notably, the 2024 Paris Olympics had to delay numerous swimming-focused events like the triathlon due to high levels of sewage in the River Seine. United States == See also ==