Drinking Water: Hidden Pollutants And Their Harmful Effects

Drinking water contamination is a serious issue that can have detrimental effects on human health and the environment. Contaminants can be physical, chemical, biological, or radiological substances, and even small amounts can be harmful if consumed. These contaminants may be naturally occurring or introduced by human activity, and they can lead to acute or chronic health effects, including cancer, kidney problems, and reproductive difficulties. In recent years, scientists have warned that water from wells and community water systems often contains unsafe levels of toxic contaminants, with certain communities being disproportionately affected. Furthermore, climate change is expected to exacerbate the challenge of finding clean drinking water sources. This complex issue requires urgent attention and a concerted effort to improve water infrastructure, strengthen standards, and enhance water treatment processes.

Characteristics and Values of Pollutants in Drinking Water

Microbial contaminants

Bacteria are everywhere in our environment, including surface waters and groundwater. Some bacteria can be harmful to human health, and drinking water with disease-causing bacteria can make you sick. Common bacterial contaminants in drinking water include Staphylococcus aureus, Escherichia, Shigella, and Campylobacter.

Viruses are another type of microbial contaminant. They can also cause diseases and have been associated with acute diarrhea and norovirus. Human enteric viruses are a particular concern as they can result in endemic infection levels if disinfection and distribution systems are inadequate.

Protozoa, such as Cryptosporidium and Giardia, have been detected in surface water and drinking water. They can cause gastrointestinal risks and are often associated with municipal wastewater contamination.

Parasites are also microbial contaminants that can be present in drinking water. Parasitic contamination has been observed in wastewater and sludge samples, and they can cause health issues such as shigellosis.

It is challenging to test drinking water for every type of pathogen. However, testing for coliform bacteria, such as E. coli, is a common method to indicate potential pathogen presence. The detection of coliform bacteria suggests that harmful pathogens may be present, which can lead to diarrhea, vomiting, cramps, nausea, headaches, fever, fatigue, and even death in certain vulnerable individuals.

While most people's bodies can fight off microbial contaminants, certain population groups, such as infants, children, the elderly, and those with weakened immune systems, are more susceptible to adverse health effects.

Chemical contaminants

The Safe Drinking Water Act defines a "contaminant" as any physical, chemical, biological, or radiological substance or matter in water other than water molecules. While the presence of contaminants does not necessarily indicate a health risk, certain contaminants may be harmful if consumed at particular levels.

Arsenic, nitrate, and fluoride are among the most common and hazardous chemical contaminants. Countries like Pakistan, India, Morocco, and Saudi Arabia have been found to have concentrations of these chemicals exceeding safety thresholds set by organizations like the World Health Organization (WHO) and the United States Environmental Protection Agency (US EPA). For example, Pakistan has faced critical levels of fluoride contamination, with concentrations reaching 30 mg/L, far surpassing recommended limits.

Other chemical contaminants of concern include disinfection byproducts, solvents, pesticides, and radionuclides like radium. Additionally, emerging contaminants, such as pharmaceuticals, personal care products (soaps, cosmetics, fragrances), and endocrine-disrupting compounds (EDCs), are gaining attention due to their unknown potential risks. Up to 90% of oral drugs pass through the human body and end up in the water supply, and trace amounts of endocrine disruptors, which can interfere with hormone function, have been detected in water supplies across countries.

Addressing these issues requires a comprehensive understanding of water quality and its impacts on human health. Organizations like the US EPA, WHO, and the European Union Council are actively working to regulate and understand the effects of various chemical contaminants.

Radiological contaminants

When radionuclides break down (decay), they release radiation. While small amounts of radiation are common in the environment, exposure to high levels can cause health issues. Drinking water containing radionuclides exposes individuals to low doses of radiation daily. Consuming water with radionuclides over many years increases the risk of cancer and other chronic health problems.

Public drinking water systems are responsible for testing and filtering out these contaminants, adhering to the standards set by regulatory agencies like the U.S. EPA. The EPA establishes Maximum Contaminant Levels (MCLs) for radionuclides in public drinking water under the Safe Drinking Water Act. Water suppliers regularly test their water sources and employ filters or other methods to ensure the water delivered to consumers is safe for drinking.

To address radionuclides in private wells, individuals can install home water treatment systems like ion exchange water softeners or reverse osmosis systems to reduce their levels. Additionally, resources are available to help understand and mitigate radiation exposure, such as reading the public water system's Consumer Confidence Reports and seeking information from state Radiation Control Programs.

While the presence of radiological contaminants in drinking water can be concerning, it is important to note that the levels are typically very low and regulated by authorities. However, individuals can take proactive steps, such as testing their water sources and implementing appropriate treatment methods, to further minimize potential health risks associated with these contaminants.

Contaminants from climate change

According to the Safe Drinking Water Act, a "contaminant" is defined as any physical, chemical, biological, or radiological substance in water other than water molecules. While small amounts of some contaminants may be present in drinking water, certain contaminants can be harmful if consumed at particular levels.

Climate change poses a serious threat to drinking water supplies worldwide. Here are some ways in which climate change contributes to drinking water contamination:

Flooding

Flooding can wash away and damage pipes that are essential for water supply systems. It can also lead to mudslides, which wash sediment, debris, and other contaminants into surface water, further compromising water quality. Floods can also cause post-flood water quality deterioration, making it unfit for drinking.

Drought

Drought conditions can reduce water availability and negatively impact water quality. For example, the Mississippi River experienced a drought due to a lack of precipitation and excessive heat, allowing saltwater from the Gulf of Mexico to travel upstream and threaten New Orleans' drinking water supply. Drought can also contribute to water-borne diseases, as seen in Mozambique's Nampula Province, where climate-related drought has led to an increase in tropical diseases like cholera and water-related illnesses.

Extreme Rainfall and Warming Water Temperatures

Fertilizer runoff and contaminated stormwater from extreme rainfall, combined with warmer water temperatures, increase the frequency and intensity of harmful algal blooms in freshwater sources. These algal blooms can produce toxins, such as cyanotoxins, that contaminate drinking water supplies.

Fire

Fires can release contaminants such as benzene and other carcinogens into the atmosphere, which can then be sucked back into the water system. The burning of human-made materials, such as plastic pipes, during fires further pollutes the water supply.

Saltwater Intrusion

As mentioned earlier, drought and reduced river volumes can allow saltwater to intrude upstream, threatening drinking water sources. This has been a concern for cities like New Orleans, where low river levels in the Mississippi River have increased the risk of saltwater contamination.

Contaminants in underserved communities

According to the Safe Drinking Water Act, a "contaminant" is defined as any physical, chemical, biological, or radiological substance or matter in water other than water molecules. While small amounts of some contaminants are to be expected in drinking water, certain contaminants can be harmful if consumed at specific levels.

Underserved communities, including communities of colour and low-income communities, often face disproportionate exposure to contaminated drinking water. This disparity is a result of unequal environmental protections and investments in water infrastructure. For instance, in 2015, a cost-saving measure led to lead contamination in the drinking water supply of Flint, Michigan, where 60% of residents are African American and 40% live below the poverty line.

In the United States, wastewater discharges are regulated by the Clean Water Act to maintain the quality of surface waters. However, the impact on downstream drinking water treatment plants (DWTPs) is rarely considered. This results in contaminants of emerging concern (CECs), such as pharmaceuticals, personal care products, and industrial chemicals, being detected in drinking water sources. Underserved communities, particularly those with smaller populations, often lack the knowledge and resources to address the impacts of wastewater discharges on their drinking water.

Furthermore, socioeconomic factors such as race and income are associated with disparities in exposure to drinking water contaminants. Studies have found that marginalized communities, including communities of colour and low-income households, face greater challenges in maintaining water quality that meets safety standards. For example, in Central Valley, California, researchers estimated that 48% of private well users live within marginalized communities, and nearly 89% of them are likely to have manganese levels in their water that exceed health advisory limits.

To address these issues, interventions such as providing pitcher filters and developing interactive web portals with information on water quality and treatment options can help underserved communities improve their access to safe drinking water.

Frequently asked questions