Water Contamination: A Frequent Threat To Our Health

Water contamination is a widespread issue that jeopardizes human health and the environment. Unsafe water is responsible for more deaths annually than war and violence combined, and the challenges are expected to increase by 2050 when global demand for freshwater is predicted to rise by a third. Water contamination occurs when physical, chemical, biological, or radiological substances degrade water quality and render it toxic. Sources of water contamination include human and animal waste, industrial and agricultural waste, natural and man-made chemicals, and soil erosion. While treatment can remove many contaminants, it may also leave behind harmful byproducts, and water can become contaminated during distribution due to breaches or corrosion.

Characteristics and Values of Water Contamination

Waterborne diseases

Water pollution occurs when harmful substances, often chemicals or microorganisms, contaminate a body of water, degrading water quality and rendering it toxic to humans or the environment. This widespread problem jeopardizes human health, killing more people each year than war and all other forms of violence combined. Water is particularly vulnerable to pollution because it is a "universal solvent", able to dissolve more substances than any other liquid on earth.

In the first part of the 20th century, germs in drinking water caused most waterborne diseases. These diseases, like cholera and typhoid, caused serious gastrointestinal illness and sometimes resulted in death. Once effective and consistent drinking water treatment, disinfection, and sanitation measures were put into place across the US, these diseases became rare. Today, waterborne diseases are responsible for many different types of illnesses, including respiratory illnesses, neurological illnesses, skin problems, gastrointestinal illnesses, and bloodstream infections.

Human and animal waste

Water pollution is a widespread problem that jeopardizes human health. It occurs when harmful substances contaminate a body of water, degrading water quality and rendering it toxic to humans or the environment. One significant source of water contamination is human and animal waste, which can introduce a range of harmful substances into water sources.

Human waste, or sewage, can contain a variety of contaminants, including biological and chemical pollutants. Biological contaminants include bacteria, viruses, and parasites, which can cause serious illnesses and diseases. Chemical contaminants in human waste can include human-made compounds such as pharmaceuticals and personal care products, as well as naturally occurring elements like nitrogen and salts.

Animal waste, particularly from agricultural livestock operations, is also a significant contributor to water contamination. More than 85% of the world's faecal waste comes from domestic animals such as poultry, cattle, sheep, and pigs. These animals can harbour zoonotic pathogens, which are transported through water runoff and can pose risks to human health. Additionally, animal waste often contains high levels of biochemical oxygen-demanding materials (BOD). For example, swine waste slurry can contain 20,000–30,000 mg BOD/L, leading to oxygen depletion in water bodies and creating a hostile environment for aquatic life.

The recent growth of concentrated animal feeding operations (CAFOs) has further intensified the issue of water contamination from animal waste. CAFOs generate a substantial volume of waste, which may contain antibiotics, veterinary pharmaceuticals, and other contaminants. These toxicants can enter nearby freshwater and marine ecosystems, impacting both environmental and human health. Inadequate waste management practices in the agricultural industry have been identified as a critical factor in the contamination of water resources.

Overall, human and animal waste are significant contributors to water contamination, introducing a range of harmful substances into water sources. Effective waste management practices and rigorous ecosystem monitoring are essential to mitigate the impacts of these contaminants on the environment and human health.

Industrial and agricultural wastewater

Water pollution is a widespread problem that jeopardizes human health. Unsafe water kills more people each year than war and all other forms of violence combined. Water pollution occurs when harmful substances, often chemicals or microorganisms, contaminate a body of water, degrading water quality and rendering it toxic to humans or the environment.

Industrial wastewater is one of the most common by-products of industrial or commercial activities. It is the water that was used to make commercial products across nearly every industry in almost all phases of production. Once this process water has been used, it is considered waste and needs to be treated before it is discharged. Industrial wastewater is not just a by-product of oil, gas, mining, and chemical manufacturing companies, but also of food and beverage processing industries.

The main concern with industrial wastewater is the increasing amount and variety of synthetic compounds contained in and discharged into the environment. These include high concentrations of dissolved solids (salts), naturally occurring radionuclides, and metals, as well as other pollutants used in drilling and well completion. For example, wastewater from fossil-fuel power stations, particularly coal-fired plants, often contains significant levels of metals such as lead, mercury, cadmium, and chromium, as well as arsenic, selenium, and nitrogen compounds.

Agricultural wastewater, on the other hand, is characterized by high levels of biological oxygen demand (BOD), chemical oxygen demand (COD), total organic carbon, and varying pH. It contains high BOD, suspended solids, and ammonia nitrogen. Agricultural wastewater is contaminated with pesticides, insecticides, animal waste, and fertilizers, which all need to be managed before the water can be safely discharged back into the environment.

To address the issue of industrial and agricultural wastewater, it is advisable to implement cleaner production methods and raise awareness to reduce the use of toxic compounds. Treatment methods such as precipitation, activated coke, and ion interchange adhesives can also be used to decontaminate trace metals in wastewater.

Chemical contaminants

Water contamination is a widespread problem that jeopardizes human health. Unsafe water kills more people each year than war and all other forms of violence combined. Water contamination occurs when harmful substances, often chemicals or microorganisms, contaminate a body of water, degrading water quality and rendering it toxic to humans or the environment.

• Nitrogen compounds: These can include nitrates and nitrites, which are commonly found in agricultural runoff from fertilizer use. High levels of nitrogen in water can lead to eutrophication, causing harmful algal blooms and depleting oxygen levels, leading to fish kills.
• Pesticides and Herbicides: These chemicals are used in agriculture to control pests and weeds but can find their way into water bodies through runoff or leaching, posing risks to aquatic life and human health.
• Heavy Metals: Metals such as lead, mercury, cadmium, and arsenic can have severe health impacts, especially for children and developing fetuses. They can enter water supplies through industrial activities, mining, or the corrosion of plumbing pipes.
• Volatile Organic Compounds (VOCs): These include chemicals like benzene, toluene, and trichloroethylene, which can contaminate water through industrial processes or the use of solvents. VOCs can have serious health effects, including cancer and damage to the nervous system.
• Pharmaceuticals: Drugs and medications that are disposed of improperly or excreted through human waste can end up in water supplies, with potential ecological and health consequences that are not yet fully understood.
• Hormone Disruptors: Chemicals that interfere with the body's endocrine system, such as certain pesticides, plasticizers, and industrial chemicals, can contaminate water sources and impact the development and reproduction of aquatic organisms.
• Per- and Polyfluoroalkyl Substances (PFAS): PFAS are a group of man-made chemicals used in various industries for their non-stick and water-repellent properties. They are highly persistent in the environment and have been linked to health issues, including cancer and developmental problems.

To prevent and mitigate chemical water contamination, it is essential to implement proper waste management practices, regulate industrial discharges, and promote sustainable agricultural practices. Additionally, the development and use of advanced water treatment technologies can help remove or reduce the levels of chemical contaminants in drinking water supplies.

Microbial contaminants

Water pollution is a widespread problem that jeopardizes human health. Unsafe water kills more people each year than war and all other forms of violence combined. Microbial contaminants are a significant source of concern within this context.

The greatest risk to public health from microbial contaminants in water is associated with the consumption of water contaminated with human and animal excreta. Waterborne pathogens, such as bacteria, viruses, and parasites, can cause acute and chronic health effects, with vulnerable subpopulations being particularly susceptible to severe disease outcomes. These pathogens can grow in the environment and are often associated with suspended solids in water, making it challenging to predict the likelihood of acquiring an infectious dose.

Sources of microbial contaminants in water include discharges from water treatment plants, decontamination stations, hospitals, and certain industries. Additionally, diffuse sources such as slurry, manure, and sludge application can also contribute to microbial contamination. Climate change, with the increase in heavy rainfall events, is expected to exacerbate the issue by impacting the behaviour and transportation of microorganisms in water.

To address the risk of microbial contamination, monitoring methods such as turbidity measurements are employed at drinking water plants. However, there is a recognized need for more relevant, simple, and fast indicators, especially in the context of climate change. Direct measurement of pathogens and indicator organisms in source waters is recommended, but resource limitations often pose a challenge. Alternative approaches include making estimations based on available data, such as sanitary surveys and indicator testing.

Frequently asked questions