Water, known as H2O, is a compound of hydrogen and oxygen. However, natural water is rarely pure H2O. Its unique molecular structure, with partial positive and negative charges, makes it an exceptional solvent. As water moves through the environment, it interacts with various materials, picking up diverse components from its surroundings. This article explores the substances that become part of water’s composition.
Naturally Occurring Components
Water naturally acquires dissolved solids as it flows over and through rocks and soil. These include minerals like calcium, magnesium, sodium, and potassium, which contribute to water’s “hardness.” Trace elements such as iron and zinc are also present. These minerals can influence the taste of water.
Gases from the atmosphere also readily dissolve into water. Oxygen, carbon dioxide, and nitrogen are commonly found in natural water bodies. Dissolved oxygen supports aquatic life. Dissolved carbon dioxide can influence water’s pH and contribute to its taste.
Natural organic matter also becomes incorporated into water from decaying plants and animals. Humic and fulvic acids are examples of these complex organic compounds. These substances result from biomass decomposition. Their presence can affect water’s color and chemical properties.
Human-Introduced Substances
Human activities introduce a different category of substances into water sources. Industrial processes can release a variety of chemicals, including heavy metals such as lead, mercury, and cadmium, along with various solvents. These pollutants can leach into water from industrial waste and accidental spills, posing risks to aquatic ecosystems and human health.
Agricultural practices also contribute significantly to water’s composition. Runoff from farms can carry pesticides, herbicides, and excess fertilizers like nitrates and phosphates into water bodies. Animal waste from agricultural operations also introduces bacteria and other contaminants. These substances can lead to issues such as harmful algal blooms and contamination of drinking water sources.
Pharmaceuticals and personal care products (PPCPs) are another concern. Residues from medications, soaps, detergents, and cosmetics enter water systems through human excretion, improper disposal, and washing. While often found in minute quantities, their long-term effects are still under investigation. Microorganisms, including pathogenic bacteria, viruses, and protozoa, can also enter water, often from sewage leaks or inadequate sanitation.
During water treatment, certain chemicals can form. Disinfection byproducts (DBPs) emerge when disinfectants, commonly chlorine, react with naturally occurring organic matter. Examples include trihalomethanes (THMs) and haloacetic acids (HAAs). Microplastics are increasingly detected in water from sources like synthetic textiles, fragmented plastic debris, and wastewater effluent.
How Water’s Origin and Treatment Affects Its Contents
The composition of water varies significantly depending on its original source. Groundwater, which filters through rock and soil, often has higher concentrations of dissolved minerals. Surface water from rivers, lakes, and reservoirs, conversely, is more susceptible to runoff, suspended solids, and organic matter from the surrounding environment.
Municipal tap water undergoes extensive treatment to remove contaminants and ensure safety. This process involves coagulation, where chemicals are added to clump particles, followed by filtration to remove solid matter. Disinfection, often using chlorine, eliminates harmful microorganisms. These steps meet water quality standards, making the water safe for consumption.
Bottled water also has diverse origins and treatments. Spring water originates from underground formations and often contains natural minerals. Purified bottled water, however, undergoes processes like distillation or reverse osmosis to remove most dissolved solids. Some bottled waters may have minerals intentionally added for taste.
Home filtration systems, such as activated carbon filters, reverse osmosis units, or UV filters, offer consumers additional ways to remove specific substances. These include chlorine, sediment, or microorganisms from their tap water.
Distilled water, created by boiling water and condensing the steam, is nearly pure H2O. This process effectively removes almost all dissolved minerals and impurities.