Water covers over 70% of the earth’s surface, and it is required for all known life forms to survive. But, over 2 billion people lack access to clean, safe water. Less than 1% of all freshwater is accessible to humans, and unsafe water kills more people than all forms of violence and war combined.
The earth’s drinkable water sources remain limited, and the challenges to obtain safe drinking water will continue to increase by 2030, when global demand for freshwater is expected to be one-third greater than it is now.
Tap water varies greatly in its purity, pH, chemical constitution, and molecular qualities. Bottled waters also vary greatly. And you will find an endless supply of arguments about what makes the best drinking water and purification systems.
Safe drinking water is essential for life to continue. Traditionally, microbiological quality of drinking water has attracted the most debate, and it is still an ongoing issue throughout the globe. The availability of safe drinking water since the second half of the nineteenth century has contributed greatly to the elimination of the spread of infectious waterborne diseases, such as typhoid fever and cholera.
However, attention towards chemical contamination in ground and surface water has grown together with the knowledge of these toxic chemical compounds and their detrimental health effects.
Water contamination comes from a variety of human activities such as agriculture, shipping, industry, and use of chemicals in households. Some of the chemicals affecting human health are the presence of toxic metals such as arsenic, lead, cadmium, mercury, and copper as well as petrochemicals, chlorinated solvents, pesticides, nitrates and pharmaceuticals. The toxic chemicals, fluoride and chlorine, are intentionally added to water.
Agriculture is the largest consumer of freshwater resources, and it is a significant water polluter. Around the world, agriculture is the leading cause of water degradation. In the United States, agricultural pollution is the top source of contamination in rivers and streams, the second-biggest source in wetlands, and the third main source in lakes. It is a major contributor of contamination to estuaries and groundwater. Pesticides, such as herbicides, fungicides, insecticides, plant growth regulators, bactericides, and defoliants impact the surface water quality. When it rains, fertilizers, pesticides, and animal waste from farms and livestock operations wash pathogens and nutrients into our waterways. Nutrient pollution, caused by excess nitrogen and phosphorus in water or air, is the number-one threat to water quality worldwide and can cause algae blooms that are harmful to wildlife.
Industry, mining and wastewater also contribute to contaminating water with heavy metals and hundreds of chemicals. Several toxic industrial solvents are regularly detected in surface waters. Many of these contaminants are poisonous to aquatic life, often reducing an organism’s life span and ability to reproduce. The contaminants make their way up the food chain as predators eat prey.
The U.S. Environmental Protection Agency (EPA) has set standards for more than 80 contaminants that may occur in drinking water and pose a risk to human health. The contaminants fall into two groups (acute and chronic) according to the health effects that they cause.
Acute effects occur within hours or days of the time that a person consumes a contaminant. People can suffer acute health effects from almost any contaminant if they are exposed to extraordinarily high levels. In drinking water, microbes are the contaminants with the greatest chance of reaching levels high enough to cause acute health effects. Most people’s bodies can fight off these microbial contaminants the way they fight off germs, and these acute contaminants typically do not have permanent effects. However, very high levels can be dangerous or deadly.
Chronic effects occur after people consume a contaminant at levels over EPA’s safety standards over the course of many years. The drinking water contaminants include chemicals (such as disinfection byproducts, solvents and pesticides), radionuclides (such as uranium, radium), and toxic elements (such as arsenic, mercury and lead). Examples of these chronic effects include cancer, liver or kidney problems, or reproductive difficulties.
The Safe Drinking Water Act of 1974 includes requirements for the Environmental Protection Agency to set standards for only 83 specific contaminants. The limited selection is based on the potential for causing adverse health effects and for known or potential occurrence in drinking water.
Arsenic
Waterborne arsenic is a major cause of disease in many parts of the world including the Indian sub-continent—particularly Bangladesh and Bengal—South America, and the Far East. Many wells in North America are contaminated with arsenic. It has been associated with skin, lung, and bladder cancers, vascular diseases, hypertension, diabetes and birth defects. A primary source of arsenic in drinking water wells is from water flowing through arsenic-rich rocks and soil. It can be further released into the environment through natural activities such as volcanic action and forest fires, as well as through human actions. Arsenic is used in paints, dyes, metals, drugs, soaps, and semiconductors. Agricultural applications, mining, and smelting also contribute to arsenic releases in the environment. These can enter the groundwater system by gradually moving with the flow of groundwater from rains, melting of snow, etc. Testing water for arsenic in areas where arsenic is a concern is an important strategy for private water well owners to safeguard the health and well-being of their family.
Lead
Lead is a toxic metal that is harmful to human health; there is NO safe level for lead exposure. Lead can enter drinking water when plumbing materials that contain lead corrode, especially where the water has high acidity or low mineral content that corrodes pipes and fixtures. The most common sources of lead in drinking water are lead pipes, faucets, and fixtures. In homes with lead pipes that connect the home to the water main, also known as lead services lines, these pipes are typically the most significant source of lead in the water. Lead pipes are more likely to be found in older cities and homes built before 1986. Among homes without lead service lines, the most common problem is with brass or chrome-plated brass faucets and plumbing with lead solder.
Young children, infants, and fetuses are particularly vulnerable to lead because the physical and behavioral effects of lead occur at lower exposure levels in children than in adults. A dose of lead that would have little effect on an adult can have a significant effect on a child. In children, low levels of exposure have been linked to damage to the central and peripheral nervous system, learning disabilities, shorter stature, impaired hearing, and impaired formation and function of blood cells.
Volatile Organic Chemicals (VOC)
The U.S. Environmental Protection Agency reported that the presence of elevated VOC concentrations in drinking water may be a concern to human health because some VOCs are carcinogens and/or may adversely affect the liver, kidneys, spleen, and stomach, as well as the nervous, circulatory, reproductive, immune, cardiovascular, and respiratory systems. Some VOCs may affect cognitive abilities, balance, and coordination, and some are eye, skin, and/or throat irritants.
Pharmaceuticals
Pharmaceuticals and their metabolites can reach water bodies through sewage systems, industrial discharges, effluents from sewage treatment plants (STPs), aquaculture, and livestock farming. Pharmaceuticals include a hundred substances which are very different in regards to chemical–physical properties and environmental behavior, although they may have strong biochemical activities. Their presence in the aquatic environment and impact on aquatic biota and on human health have not yet been studied adequately. Experimental evidence indicates that pharmaceuticals may cause harmful effects, such as morphological, metabolic and sex alterations on aquatic species, and induction of antibiotic resistance in aquatic pathogenic microorganisms.