Domestic waste water pollutants

Discharge of dangerous substances into domestic waste water

Nature

In addition to the increased production of sewage due to the growth of population, the per capita production of waste water is growing: in many cities it may amount to 600 litres per day per person. At the same time, its content of organic and mineral pollutants is also large and may amount to 10 litres of wet sludge per person daily, or about 50 kg of dry solids per person per year. Domestic and municipal sewage contains decomposable organic matter that exerts a demand on the oxygen resources of the receiving waters. This biochemical oxygen demand (BOD) is a measure of the weight (per unit volume of water or waste water) of dissolved oxygen consumed in the biological processes that degrade organic matter; it is determined by means of a standard test procedure. BOD values range from approximately 1mg/litre (for natural waters) to 300-500mg/litre (for untreated domestic sewage). The organic matter consists primarily of carbohydrates, proteins from animal matter and miscellaneous fats and oils. The specific classes of organic compounds found in sewage include amino-acids, fatty acids, soaps, esters, anionic detergents, amino-sugars, amines, amides, and many others. Much of the impurity in municipal wastes is material capable of settling, which may be deposited at the bottom of receiving waters to form deep layers of organic sludge. Dissolved salts in the form of ions such as sodium, potassium, calcium, manganese, ammonium, chloride, nitrate, nitrite, bicarbonate, sulphate and phosphate are the main inorganic constituents of sewage and other waste-waters. There are also significant traces of heavy metals, such as mercury, synthetic chemical and drugs. Domestic and municipal sewage invariably contains a variety of micro-organisms, some of which may be pathogenic. Although most human intestinal pathogens do not survive for extended periods outside the body of the host, there is evidence that they may remain sufficiently viable in different types of aquatic environment to be able to infect man.

Background

The significance of domestic wastewater pollutants emerged in the mid-20th century, as rapid urbanization and population growth led to visible degradation of water bodies worldwide. Early studies in Europe and North America linked untreated household effluents to eutrophication and public health crises. Over subsequent decades, global monitoring revealed persistent contaminants—such as pharmaceuticals and microplastics—prompting international concern and policy responses. Recognition of the problem has since expanded, highlighting its pervasive impact across diverse socio-economic contexts.

Incidence

Domestic wastewater pollutants are a pervasive issue, with the World Health Organization estimating that over 80% of global wastewater is released into the environment without adequate treatment. This widespread discharge introduces nutrients, pathogens, pharmaceuticals, and microplastics into rivers, lakes, and coastal waters, threatening water quality and public health in both developed and developing regions.
In 2023, the city of Lagos, Nigeria, experienced severe contamination of its waterways due to untreated domestic wastewater. Local reports documented increased levels of fecal bacteria and chemical residues in the Lagos Lagoon, resulting in fish kills and heightened risks of waterborne diseases among nearby communities.

Claim

Domestic wastewater pollutants are a critical and urgent problem that cannot be ignored. Every day, harmful chemicals, plastics, and pathogens from our homes contaminate water sources, threatening public health and destroying ecosystems. The careless disposal of household waste is poisoning our environment and endangering future generations. Immediate action and stricter regulations are essential to prevent irreversible damage. We must recognize domestic wastewater pollution as a top priority before it’s too late.

Counter-claim

Frankly, the concern over domestic wastewater pollutants is vastly overstated. Modern treatment plants already handle most contaminants efficiently, making the issue negligible for public health and the environment. Compared to industrial pollution or climate change, domestic wastewater is a minor blip. Resources and attention should be directed toward truly pressing global challenges, not exaggerated fears about what goes down our household drains. Let’s focus on real problems, not manufactured ones.