Water pollution
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. This definition applies when contaminants mix with lakes, rivers, oceans, aquifers, reservoirs and groundwater. The contamination usually results from human activities rather than natural processes alone. Four main sources drive this issue: sewage discharges, industrial activities, agricultural activities, and urban runoff including stormwater. These inputs degrade aquatic ecosystems and spread water-borne diseases when people use polluted water for drinking or irrigation. One practical example involves the 90 percent of water in Chinese cities that remains polluted as of recent estimates. Another case shows how about 4.5 billion people globally lacked safely managed sanitation as of 2017 according to UN data. Such conditions lead to open defecation practices where human feces move into surface waters during rain events or floods. Simple pit latrines may also get flooded during heavy rainfall seasons. The result is a marked shift in the ability of water bodies to support biotic communities like fish populations.
Contaminants reach water bodies through raw sewage or treated sewage discharges containing various chemical compounds found in personal hygiene and cosmetic products. Hormones from animal husbandry and residue from human hormonal contraception methods enter these systems alongside synthetic materials such as phthalates that mimic hormones in their action. Natural Environmental Research Council studies found river sewage pollution disrupting fish hormones even at very low concentrations. Insecticides and herbicides often arrive via agricultural runoff while pathogens like Hepatovirus A may be present in treated wastewater outflows. Bacteria, viruses, protozoans and parasitic worms are examples of pathogens that can be found in wastewater. Indicator organisms such as total coliforms or fecal coliforms including Escherichia coli help investigate pathogenic pollution because detecting actual pathogens is difficult and costly due to low concentrations. Some microorganisms sometimes found in contaminated surface waters include Burkholderia pseudomallei, Cryptosporidium parvum, Giardia lamblia, Salmonella, norovirus and other viruses. Petroleum hydrocarbons including fuels like gasoline, diesel fuel, jet fuels, and fuel oil enter water from spills or storm water runoff. Volatile organic compounds such as improperly stored industrial solvents create problematic species like organochlorides including polychlorinated biphenyl PCBs and trichloroethylene. Per- and polyfluoroalkyl substances PFAS persist in the environment at high levels particularly in aquatic and marine ecosystems where they cause water pollution.
A study published in 2017 stated that polluted water spread gastrointestinal diseases and parasitic infections and killed 1.8 million people globally. Elevated water temperatures decrease oxygen levels which can kill fish and alter food chain composition while reducing species biodiversity. Oxygen-depleting substances may be natural materials such as plant matter as well as human-made chemicals causing turbidity that blocks light and disrupts plant growth. High concentrations of naturally occurring substances can have negative impacts on aquatic flora and fauna. Nitrogen pollution causes eutrophication especially in lakes leading to anoxia severe reductions in water quality and harm to fish and other animal populations. Ocean acidification represents another impact caused by the ongoing decrease in pH value of Earth's oceans due to uptake of carbon dioxide from the atmosphere. Persistent exposure to pollutants through water increases environmental health hazards raising the likelihood for one to develop cancer or other diseases. Fecal sludge collected from pit latrines dumped into rivers creates visible pollution examples seen in places like the Korogocho slum in Nairobi Kenya. The introduction of aquatic invasive organisms constitutes biological pollution affecting ecosystem integrity. Microplastics persist in environments at high levels particularly in aquatic and marine ecosystems where they cause water pollution with 35 percent of all ocean microplastics coming from textiles clothing primarily due to erosion of polyester acrylic or nylon-based clothing during washing processes.
Environmental scientists prepare water autosamplers to conduct physical chemical and biological tests measuring specific properties of organisms to obtain information on surrounding environment. Common physical tests include temperature Specific conductance or electrical conductance EC solids concentrations like total suspended solids TSS and turbidity. Water samples may be examined using analytical chemistry methods quantifying parameters such as pH BOD chemical oxygen demand COD dissolved oxygen DO total hardness nutrients including nitrogen and phosphorus compounds metals copper zinc cadmium lead mercury oil and grease surfactants pesticides. Biological testing involves use of plant animal or microbial indicators monitoring health of aquatic ecosystem. One example group includes copepods and other small water crustaceans present in many water bodies monitored for changes biochemical physiological behavioral indicating problem within their ecosystem. Standardized validated analytical test methods for water and wastewater samples have been published by various organizations. Some methods conducted in situ without sampling measure temperature directly while others involve collection followed by specialized laboratory analysis. Biomonitor or bioindicator measurement reveals degree of ecosystem or environmental integrity present through function population status of specific species. These tools help identify toxic substances and track progress toward cleaner water environments globally.
The U.S. Clean Water Act CWA defines point
source for regulatory enforcement purposes amended in 1987 to include municipal storm sewer systems industrial storm water from construction sites. In Philippines Republic Act 9275 known as Philippine Clean Water Act of 2004 governs wastewater management stating policy to protect preserve revive quality fresh brackish marine waters. In 2024 The Royal Academy of Engineering released study into effects wastewater on public health in United Kingdom gaining media attention with comments from UK leading health professionals including Sir Chris Whitty. Outlining 15 recommendations for various UK bodies dramatically reduce public health risks increasing water quality rivers lakes. After report release The Guardian newspaper interviewed Whitty who stated improving water quality sewage treatment should be high level importance public health priority comparing it to eradicating cholera in 19th century following improvements to sewage treatment network. Study identified low water flows rivers saw high concentration levels sewage times flooding heavy rainfall. British media warned parents dangers paddling shallow rivers during warm weather despite growth number people using coastal inland waters recreationally. Most notably 2024 Paris Olympics delayed numerous swimming-focused events like triathlon due to high levels sewage River Seine. Cities large combined systems not pursued system-wide
separation projects due high cost but implemented partial separation projects green infrastructure approaches.
Municipal wastewater treated by centralized sewage treatment plants decentralized wastewater systems nature-based solutions onsite sewage facilities septic tanks. Well-designed operated systems secondary treatment stages advanced tertiary treatment remove 90 percent or more pollutant load sewage. Some plants additional systems remove nutrients pathogens reducing discharges micropollutants though resulting large financial costs environmentally undesirable increases energy consumption greenhouse gas emissions. Sewer overflows storm events addressed timely maintenance upgrades sewerage system US cities large combined systems not pursued system-wide separation projects due high cost implementing partial separation projects green infrastructure approaches. Municipalities installed additional CSO storage facilities expanded sewage treatment capacity. Sediment from construction sites managed installation erosion controls mulching hydroseeding sediment basins silt fences. Discharge toxic chemicals motor fuels concrete washout prevented use spill prevention control plans specially designed containers overflow controls diversion berms. Erosion caused deforestation changes hydrology soil loss water runoff results loss sediment potentially water pollution. Waste stabilization ponds low cost treatment option sewage UV light sunlight degrades some pollutants waste stabilization ponds sewage lagoons. Use safely managed sanitation services prevents water pollution caused lack access sanitation. Effective control urban runoff includes reducing speed quantity flow preventing water pollution through integrated measures trans-boundary considerations complementary supplementary control measures life-cycle impacts
chemical mixtures.
Up Next
Continue Browsing
Common questions
What is the definition of water pollution according to the script?
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. This definition applies when contaminants mix with lakes, rivers, oceans, aquifers, reservoirs and groundwater.
How many people lacked safely managed sanitation globally as of 2017?
About 4.5 billion people globally lacked safely managed sanitation as of 2017 according to UN data. Such conditions lead to open defecation practices where human feces move into surface waters during rain events or floods.
Which specific microorganisms are found in contaminated surface waters?
Some microorganisms sometimes found in contaminated surface waters include Burkholderia pseudomallei, Cryptosporidium parvum, Giardia lamblia, Salmonella, norovirus and other viruses. Indicator organisms such as total coliforms or fecal coliforms including Escherichia coli help investigate pathogenic pollution because detecting actual pathogens is difficult and costly due to low concentrations.
When did the U.S. Clean Water Act amend point source regulations to include municipal storm sewer systems?
The U.S. Clean Water Act CWA defines point source for regulatory enforcement purposes amended in 1987 to include municipal storm sewer systems industrial storm water from construction sites. In Philippines Republic Act 9275 known as Philippine Clean Water Act of 2004 governs wastewater management stating policy to protect preserve revive quality fresh brackish marine waters.
What percentage of ocean microplastics comes from textiles clothing?
Microplastics persist in environments at high levels particularly in aquatic and marine ecosystems where they cause water pollution with 35 percent of all ocean microplastics coming from textiles clothing primarily due to erosion of polyester acrylic or nylon-based clothing during washing processes.