ABSTRACT
Potable water is safe to drink. Municipalities may use surface water or ground water. Surface water drains from areas of land called watersheds. Used, discharged water is called effluent. Aquifers underground contain appreciable amounts of water. The water table refers to the underground water level. Applications of fertilizers and pesticides may pollute through runoff into surface waters or infiltration into groundwater. This pollution cannot be traced to a single source and is called non-point-source pollution. Point-source pollution can be attributed to a source. Elevated levels of nitrogen and phosphorus may cause eutrophication, a condition that includes low oxygen levels in water (hypoxia), algae blooms, and fish kills. Organochlorine pesticides are highly toxic and persistent in the environment and food chain. Pesticides known as endocrine disruptors interfere with natural hormones and adversely affect reproduction in mammals, including humans. Polycyclic aromatic hydrocarbons (PAHs) are found in pavement coatings. They contain known carcinogens, teratogens, mutagens, and toxins. Bioremediation and phytoremediation describe the use of biological organisms or plants to remove toxic substances. A wetland is a place where water-saturated land dominates. Hydrology studies the relationship between water movement and the land. A constructed wetland is a built system that can bio-filter wastes and effluent. Emergent species of plants are able to withstand 6–24 in. of water.
