1,4-dioxane is a synthetic industrial chemical that is completely miscible in water. The largest sources of 1,4-dioxane in drinking water sources are wastewater discharge, unintended spills, leaks, and historical disposal practices of its host solvent, 1,1,1-trichloroethane (TCA). 1,4-dioxane readily dissolves into groundwater, and its movement is not retarded significantly by sorption to soil particles. It is highly mobile, recalcitrant to microbial degradation, and has a low tendency to volatilize from water. Conventional water treatment practices (e.g., coagulation, sedimentation, and filtration), aeration, GAC adsorption, ozone, UV, and biofiltration have proven to be ineffective at removing 1,4-dioxane from water. Advanced oxidation processes including a combination of hydrogen peroxide and ferrous iron, ozone and hydrogen peroxide, and UV and hydrogen peroxide have been shown to be effective for oxidizing 1,4-dioxane.
Cyanobacteria are photosynthetic bacteria that are common in all freshwater and marine environments. They were historically called blue-green algae but their structure, genetics, and physiology clearly identify them as bacteria. Cyanobacteria in freshwater systems are widely recognized as sources of toxins (cyanotoxins) and unpleasant tastes and odors in water supplies. Cyanobacteria are a normal component of the natural biota and tolerate a wide range of climatic conditions and environments. A rise in the number of cyanobacterial blooms, caused by eutrophication from decaying plant materials and man-made pollution, is resulting in the production of more taste and odor compounds and natural toxins, which demands the attention of water treatment authorities. Although cyanotoxins are less commonly found in drinking water than taste and odor compounds, their high toxicity is of great concern. Due to global climate change, toxin-producing cyanobacteria are spreading into more temperate regions and becoming a more widespread problem.
Fluoride is a naturally occurring compound derived from fluorine, the 13th most abundant element on Earth. It is found in rocks, soil, and fresh and ocean water. Fluoride is present naturally in almost all foods and beverages including water, but levels can vary widely. It is added to drinking water to provide public protection from dental caries. In January 2011, EPA announced their intention to review the drinking water regulations for fluoride. In response to regulatory actions, the Water Research Foundation produced this document to summarize occurrence of fluoride in natural waters, regulations, and treatment. It also provides resources for additional reading and research.
Hexavalent chromium or Chromium (VI), is a form of the metallic element chromium. It is generally used or produced in industrial processes and has been demonstrated to be a human carcinogen when inhaled. Water sources can be affected by hexavalent chromium naturally or through contamination plumes from industrial centers, landfills, and improper discharge of industrial processing streams. The health effects of hexavalent chromium through ingestion—the dominant exposure route for drinking water—have seen limited study and yielded uncertain conclusions.
The water sector and the planning and development community have a symbiotic relationship which usually goes unrecognized, and therefore, is not realized. Without adequate water resources and water infrastructure, urban development and redevelopment can be stymied. An approach gaining favor with water managers is Integrated Urban Water Management (IUWM), sometimes also called One Water. IUWM principles recognize that water from all sources must be managed holistically and cooperatively to meet social, economic, and environmental needs. This state of the science, written by WRF staff and originally published by the American Planning Association in their online publication, PAS Memo, explores the challenges and opportunities of IUWM and presents the need for cooperation and leadership among urban planners and water service personnel using IUWM to move toward more water-resilient and sustainable communities.
This summary of relevant completed and ongoing Water Research Foundation (WRF) research projects is meant to help with a basic understanding of the issues surrounding lead and copper. Since the late 1980’s, WRF has funded over 40 research projects related to lead and copper corrosion with a combine value at more than $13 million. All projects with Pb and Cu corrosion implications are described in this paper, which is updated annually.
Manganese is an element that occurs naturally in water, soil, air, and food, and can be found in North American ground and surface water supplies. Manganese chemistry, treatment, and impacts can be very complex. Typically, utilities have problems with manganese when they experience concentrations spikes and are not prepared to treat it. Conversely, utilities that have consistently higher levels of manganese usually have an effective treatment plan. Water utilities have historically managed manganese because of its potential to cause aesthetic issues such as black water events, unpleasant tastes and odors, and laundry staining, as well as its tendency to accumulate in distribution systems and cause operational problems.
Perchlorate is a chemical primarily used in the manufacturing of explosives and rocket propellants for the defense and aerospace industries. Low levels of ammonium perchlorate have also been found to occur naturally in the environment. In 1997, elevated levels of perchlorate were discovered in California drinking water supplies using a new, more sensitive detection technique. More recent occurrence studies have found perchlorate contamination in both groundwater and surface waters serving as drinking water sources for more than 16 million people in at least 26 states nationwide, though most often in the Southwest.
Radionuclides are radioactive isotopes that can occur naturally or result from manmade sources. Natural radiation comes from cosmic rays, naturally-occurring radioactive elements in the earth’s crust, and radioactive decay products. Since these radionuclides are present in soil and rock, they can also be found in groundwater and surface water. Typical radionuclides found in drinking water sources are isotopes of radium, uranium, and radon, among others. Fission products from manmade nuclear reactions are also of concern today, particularly radioactive cesium and iodine. The three basic types of radiation are alpha particles, beta particles, and gamma rays. Alpha particles are positively charged helium atoms; beta particles are negatively charged electrons, and gamma rays are high-energy electromagnetic waves.
In addition to making sure the water at customers' taps is safe to drink, water providers must also meet customer expectations for the water's aesthetic characteristics—its taste, odor, and appearance. Although most contaminants that cause aesthetic problems in drinking water are not considered a threat to human health, unpleasant tastes and odors are the most common cause of customer complaints, and they often play a role when customers choose alternative supplies such as bottled water. Because aesthetic characteristics are not usually related to public health, they are regulated by secondary standards—water quality goals that are not mandatory or enforced in most states. Nevertheless, customers who find the taste or smell of tap water disagreeable often assume the water is of poor quality and, therefore, unsafe to drink. Thus, water utilities need to be proactive in identifying and mitigating taste and odor episodes.