Urban Water Pollution: Sources And Solutions

Urban areas are a significant source of water pollution, with their dense populations, industrial activity, and wastewater runoff all contributing to the degradation of water quality. As cities continue to expand and urbanize, the impact of human activity on aquatic ecosystems becomes more pronounced. This is particularly evident in rivers, which act as a conduit for various pollutants, including nutrients, microplastics, chemicals, and pathogens. The consequences of this pollution are far-reaching, affecting both the environment and public health, as contaminated water sources can lead to waterborne diseases and a decline in drinking water quality. Effective wastewater treatment and sustainable urbanization practices are crucial in mitigating these issues and ensuring clean water availability for both urban and upstream communities.

Industrial discharges and mobile sources

Urban areas are densely populated, with people, buildings, and businesses sharing the same relative space and resources. This means that environmental impacts, including water pollution, are concentrated in smaller areas, such as waterways. Urban waters are particularly vulnerable to pollution from various sources, and one of the significant contributors is industrial discharges.

Industrial Discharges

Industrial waste is any waste generated by manufacturing or industrial processes. This includes a range of materials such as cafeteria garbage, dirt and gravel, masonry and concrete, scrap metals, trash, oil, solvents, chemicals, organic matter, and various other similar wastes. These wastes can be solid, liquid, or gases held in containers, and they are classified as either hazardous or non-hazardous. Hazardous waste can result from manufacturing processes and includes substances like cleaning fluids, paints, or pesticides. Non-hazardous waste, on the other hand, does not meet the regulatory definition of hazardous waste.

Industrial wastewater often contains specific chemical compounds, with toxic wastes and organic pollutants being the primary concern. The processing of industrial chemicals and the food products industry are significant contributors to this type of pollution. While most major industries have treatment facilities for their industrial effluents, small-scale industries often lack the necessary resources to invest in pollution control equipment. As a result, their discharges can contaminate water bodies, making it unfit for drinking, recreation, agriculture, and industrial use. Contaminated water also leads to the destruction of aquatic life and a reduction in their reproductive abilities.

Mobile Sources

Mobile sources of water pollution refer to vehicles and vessels with internal combustion, jet, or diesel engines. This includes automobiles, planes, trains, and boats, all of which contribute to water pollution. While airplanes are a significant contributor to air pollution, cars and trucks are more relevant to urban water pollution. Older vehicles, especially those manufactured before the late 1970s, tend to pollute more than newer ones. Modern cars still release pollutants such as hydrocarbons, benzene, nitrogen oxides, sulphur dioxide, and carbon monoxide.

The impact of mobile sources on water pollution is significant. Oil pollution in our seas, for example, often comes from land-based sources like cars and trucks, with oil and gasoline dripping from them every day. Additionally, the regular operations of the shipping industry, through legal and illegal discharges, contribute to the presence of oil in global waters.

Poor wastewater treatment

Urban areas contribute to water pollution through various means, one of the most significant being poor wastewater treatment. Wastewater, also known as used water, comes from residential, commercial, and industrial activities. It contains a range of contaminants, including pathogens, phosphorus, nitrogen, sewage, heavy metals, toxic chemicals, oils, grease, and debris.

The issue of poor wastewater treatment is prevalent, with more than 80% of wastewater globally flowing back into the environment without proper treatment. This figure is even higher in the least developed countries, where sanitation and wastewater treatment infrastructure are inadequate. In these countries, only a small fraction of domestic and urban wastewater is treated before being discharged into water bodies. For example, in some developing countries, less than 5% of wastewater is treated, leading to water-related diseases such as cholera and schistosomiasis.

The consequences of untreated or poorly treated wastewater are severe. When released into water bodies, it contaminates rivers, reservoirs, lakes, and seas, leading to environmental pollution and adverse effects on human health. According to the United Nations, more than 80% of diseases and 50% of child deaths worldwide are associated with inadequate water quality. Poor wastewater treatment also impacts ecosystems, damaging natural habitats and reducing biodiversity.

Furthermore, inadequate wastewater treatment contributes to the pollution of groundwater and surface water. In many areas, industries continue to discharge untreated wastewater directly into watercourses, leading to the contamination of water sources used for drinking and irrigation. This issue is particularly concerning in urban areas with centralized water sources, as pollution can affect the drinking water quality for a large number of people, creating public health hazards.

To address the issue of poor wastewater treatment, several interventions can be implemented. Firstly, investing in wastewater treatment infrastructure and upgrading existing facilities are crucial. This includes constructing new treatment plants, improving sewage systems, and adopting advanced treatment technologies. Additionally, promoting the recycling and safe reuse of wastewater can help reduce pollution and conserve water resources. Implementing regulations and standards for wastewater discharge, with regular monitoring and enforcement, is also essential to ensure that treatment processes are effective and comply with environmental standards.

Lack of access to basic services

Urban areas contribute to water pollution through various sources, including industrial discharges, mobile sources (e.g. cars and trucks), residential and commercial wastewater, trash, and polluted stormwater runoff. However, one of the critical factors that often gets overlooked is the "lack of access to basic services" in these urban settlements. This issue is prevalent in both developing and developed nations and has severe consequences for public health and the environment.

In developing countries, rapid urbanization has outpaced the development of essential water and sanitation infrastructure. As a result, millions of people in fast-growing towns and cities are left without access to safely managed water and sanitation services. This lack of access gives rise to unsanitary "slum" areas, which pose a significant health risk to the entire city and beyond. Unsanitary conditions in these neighbourhoods create a constant threat of waterborne disease outbreaks, such as cholera, typhoid, and dysentery, which can devastate vulnerable communities. Moreover, the density and volume of unserved urban populations in these settings mean that any disease outbreak can spread rapidly through the municipality and the rest of the country.

Even in developed countries like the United States, water poverty is a pressing issue. Despite having utility providers that typically cover installation and maintenance costs for water and sewer lines in urban areas, certain communities are still left behind. For instance, in California and Puerto Rico, families have to drive long distances to obtain basic water supplies. In West Virginia, residents resort to drinking from polluted streams, and in Alabama, sewage flooding in yards poses health risks and restricts children's outdoor play. These disparities are often rooted in precarious housing conditions and systemic social and racial inequalities.

The lack of access to basic services in urban areas also exacerbates environmental challenges. Urban development has been a significant driver of environmental change in the United States, with urban land consumption far outpacing population growth. The removal of trees and vegetation during urbanization leads to increased stormwater runoff and erosion, contributing to polluted stormwater runoff that contaminates water bodies. Additionally, inadequate management of urban wastewater results in dangerous levels of contamination or chemical pollution in drinking water sources, further compromising both human and environmental health.

To address these issues, governments and policymakers must prioritize public health and environmental sustainability in urban areas. This includes implementing interventions to improve water and sanitation services, such as safe wastewater treatment, and adopting roadmaps like the New Urban Agenda, which aims to build cities that protect the environment while promoting prosperity and social wellbeing. By ensuring universal access to safe and affordable drinking water, as recognized by the UN General Assembly in 2010, we can safeguard public health, reduce poverty, and mitigate the impacts of water pollution on communities and the environment.

Stormwater runoff

The impact of stormwater runoff on water pollution is exacerbated by the high population density in urban areas. With more people living in close proximity, the concentration of pollutants in waterways is higher, further degrading water quality. Additionally, the removal of trees and vegetation during the urbanization process reduces the natural buffers that would normally slow down and filter stormwater. This leads to increased erosion and more rapid runoff, exacerbating the problem.

To mitigate the effects of stormwater runoff, green infrastructure solutions have been proposed. These techniques aim to slow down and infiltrate stormwater runoff, allowing plants to filter out pollutants before they reach water bodies. Examples of green infrastructure include rain gardens, pervious pavement, rain barrels, and green roofs. By mimicking natural hydrologic processes, these solutions can reduce the volume of runoff and improve water quality.

While urbanization has altered the way stormwater behaves, proper management can help mitigate its negative impacts. Implementing natural stormwater management approaches, such as minimizing impervious surfaces and preserving natural features, can help protect the environment and reduce pollution. By adopting these strategies, communities can improve water quality and safeguard the health of both urban and upstream residents who rely on these water sources.

Sewage overflows

There are several factors that contribute to sewage overflows in urban areas. One significant factor is the increase in storm runoff due to urbanization. As urban areas develop, there is often a removal of trees and vegetation, which naturally absorb rainwater. With less vegetation to slow it down, water runs off faster during storms, overwhelming sewer systems. Additionally, urban areas tend to have a high population density, which increases the volume of wastewater and sewage that needs to be treated.

Inadequate sewer infrastructure can also lead to sewage overflows. In many urban areas, the sewer systems are old and failing, unable to handle the volume of wastewater and stormwater runoff. Blockages, inadequate carrying capacity, leaking pipes, and power outages at pumping stations are common issues that contribute to sewage overflows. Climate change is expected to exacerbate the problem, as more intense and frequent storms are predicted in certain regions, increasing the risk of sewer overflows.

The consequences of sewage overflows can be severe. Untreated sewage released into waterways can cause waterborne diseases and harm ecosystems. Germs and pathogens in sewage can linger even after the visible signs of contamination have dispersed, posing risks to humans who come into contact with the water through swimming, boating, or fishing. It is estimated that 3.5 million Americans fall ill each year due to contact with contaminated water.

To address the issue of sewage overflows, several measures can be taken. Firstly, investing in upgrading sewer infrastructure is crucial. This includes repairing and expanding pipe capacities and improving pumping stations. Additionally, implementing natural solutions, such as planting trees and restoring wetlands, can help absorb stormwater and reduce the risk of overflows. Creating green roofs, like the Ford Motor Company's project in Dearborn, MI, can also significantly reduce rainwater entering sewer systems. Finally, strong notification programs are essential to alert the public when there is a risk of exposure to raw sewage, allowing them to take necessary precautions to protect their health.

Frequently asked questions