Do You Know What's in your Water?
Common water contaminants iron and manganese are not health hazards but can cause offensive taste, appearance, and staining.Iron and manganese are common metallic elements found in the earth's crust. Water percolating through soil and rock can dissolve minerals containing iron and manganese and hold them in solution. Occasionally, iron pipes also may be a source of iron in water. In deep wells, where oxygen content is low, the iron/manganese-bearing water is clear and colorless. In such water, the iron and manganese are in dissolved form. Water from the tap may be clear, but when exposed to air, iron and manganese are oxidized (combine with oxygen to become an oxide) and change from colorless, dissolved forms to colored, solid forms (often in the form of very small particles). Iron and manganese can affect the flavor and color of food and water. They may react with tannins in coffee, tea, and some alcoholic beverages to produce a black sludge, which affects both taste and appearance. Manganese can be objectionable in water even when present in smaller concentrations than iron. Iron will cause reddish-brown staining of laundry, porcelain, dishes, utensils, and even glassware. Manganese acts in a similar way but causes a brownish-black stain. Soaps and detergents do not remove these stains, and use of chlorine bleach and alkaline builders (such as and carbonate) may intensify the stains. Iron and manganese deposits will build up in pipelines, pressure tanks, water heaters, and water softeners. This reduces the available quantity and pressure of the water supply. Iron and manganese accumulations become an economic problem when water supply or water softening equipment must be replaced. There also are associated increases in energy costs from pumping water through constricted pipes or heating water with electric heating rods coated with iron or manganese mineral deposits.
Although there are some bacteria in all ground waters, and in general they carry out beneficial processes, some bacteria or other microorganisms (e.g., protozoa, viruses) may cause disease in humans. Naturally some microorganisms have learned to live on or in the human body. Many of these microorganisms do no harm, and are even beneficial because they compete with other microorganisms that might cause disease if they could become established in or on our bodies. A few microorganisms (called pathogens) can cause disease in humans. Some of these disease-causing microorganism are closely associated with humans and other warm-blooded animals. These pathogens are transmitted from one organism to another by direct contact, or by contamination of food or water. Many of the pathogens which cause gastrointestinal disease are in this category. Several human gastrointestinal pathogens produce toxins which act on the small intestine, causing secretion of fluid which results in diarrhea. Cells of the pathogen are shed in the feces, and if these cells contaminate food or water which is then consumed by another person, the disease spreads. Other pathogens are "opportunists" : they may not be closely associated with humans or other mammals and they rarely cause disease in healthy adults. Instead, these may be common bacteria or fungi which exist in soil or water, but may cause disease in persons already weakened by a pre-exisiting disease.
The fecal indicator bacteria (Escherichia coli, fecal coliforms, fecal streptococci) are typically used to measure the sanitary quality of water for recreational, industrial, agricultural and water supply purposes. The fecal indicator bacteria are natural inhabitants of the gastrointestinal tracts of humans and other warm-blooded animals. These bacteria in general cause no harm. They are released into the environment with feces, and are then exposed to a variety of environmental conditions that eventually cause their death. In general, it is believed that the fecal indicator cannot grow in natural environments, since they are adapted to live in the gastrointestinal tract. Studies have shown that fecal indicator bacteria survive from a few hours up to several days in surface water, but may survive for days or months in lake sediments, where they may be protected from sunlight and predators. In ground water, temperature, competition with bacteria found naturally in the water, predation by protozoa and other small organisms, and entrapment in pore spaces may all contribute to their demise. We assume that pathogens similar to the fecal indicator bacteria die at the same rate as fecal indicator bacteria. Therefore, if we find relatively high numbers of fecal indicator bacteria in an environment, we assume that there is an increased likelihood of pathogens being present as well. Unfortunately, some pathogenic bacteria, viruses and protozoans may have special survival mechanisms, such as cyst formation in Cryptosporidium, or attachment of viruses to particles, so that waters free of fecal indicator bacteria may still harbor these microorganisms. This is even true of water which has undergone treatment for drinking water purposes.
There is no clear way to associate risk of disease with the bacteriological quality of ground water and measured by the presence of fecal indicator bacteria. First, there is no direct association between the presence of fecal indicator bacteria and the presence of specific pathogens. Second, individuals are not equally susceptible to pathogens. Whether or not a pathogen is successful in causing disease is related to the health of the exposed individual and the state of his or her immune system, as well as to the number of pathogen cells required to make the person ill. Some pathogens can cause disease when only a few cells are present. In other cases, many cells are required to make a person ill. Children, elderly persons and persons with pre-existing illnesses are more susceptible to many pathogens than are healthy young or middle-aged adults. Third, it would be difficult to monitor for every possible pathogen. Each type of pathogen requires a specific test and many of these tests are time-consuming or expensive. Monitoring for each type of known pathogen would be prohibitively expensive. Finally, new pathogens are still being discovered. It was only about 5 years ago that a specific bacterium was identified as a cause of stomach ulcers in humans. In addition, "old" bacteria are acquiring new "tricks" in that they are becoming resistant to antibiotics and are re-emerging as serious pathogens. The issue of emerging infectious disease, and a call for the strengthening of our public health knowledge base and infrastructure was made by the Centers for Disease Control (CDC) in 1994.
The fecal indicator bacteria (Escherichia coli, fecal coliforms, fecal streptococci) are typically used to measure the sanitary quality of water for recreational, industrial, agricultural and water supply purposes. The fecal indicator bacteria are natural inhabitants of the gastrointestinal tracts of humans and other warm-blooded animals. These bacteria in general cause no harm. They are released into the environment with feces, and are then exposed to a variety of environmental conditions that eventually cause their death. In general, it is believed that the fecal indicator cannot grow in natural environments, since they are adapted to live in the gastrointestinal tract. Studies have shown that fecal indicator bacteria survive from a few hours up to several days in surface water, but may survive for days or months in lake sediments, where they may be protected from sunlight and predators. In ground water, temperature, competition with bacteria found naturally in the water, predation by protozoa and other small organisms, and entrapment in pore spaces may all contribute to their demise. We assume that pathogens similar to the fecal indicator bacteria die at the same rate as fecal indicator bacteria. Therefore, if we find relatively high numbers of fecal indicator bacteria in an environment, we assume that there is an increased likelihood of pathogens being present as well. Unfortunately, some pathogenic bacteria, viruses and protozoans may have special survival mechanisms, such as cyst formation in Cryptosporidium, or attachment of viruses to particles, so that waters free of fecal indicator bacteria may still harbor these microorganisms. This is even true of water which has undergone treatment for drinking water purposes.
There is no clear way to associate risk of disease with the bacteriological quality of ground water and measured by the presence of fecal indicator bacteria. First, there is no direct association between the presence of fecal indicator bacteria and the presence of specific pathogens. Second, individuals are not equally susceptible to pathogens. Whether or not a pathogen is successful in causing disease is related to the health of the exposed individual and the state of his or her immune system, as well as to the number of pathogen cells required to make the person ill. Some pathogens can cause disease when only a few cells are present. In other cases, many cells are required to make a person ill. Children, elderly persons and persons with pre-existing illnesses are more susceptible to many pathogens than are healthy young or middle-aged adults. Third, it would be difficult to monitor for every possible pathogen. Each type of pathogen requires a specific test and many of these tests are time-consuming or expensive. Monitoring for each type of known pathogen would be prohibitively expensive. Finally, new pathogens are still being discovered. It was only about 5 years ago that a specific bacterium was identified as a cause of stomach ulcers in humans. In addition, "old" bacteria are acquiring new "tricks" in that they are becoming resistant to antibiotics and are re-emerging as serious pathogens. The issue of emerging infectious disease, and a call for the strengthening of our public health knowledge base and infrastructure was made by the Centers for Disease Control (CDC) in 1994.
Total dissolved solids (TDS) is a measurement of the amount of dissolved ions in water. It is predominantly comprised of inorganic salts (calcium, magnesium, potassium, sodium, bicarbonates, chlorides and sulfates), many of which are necessary life-sustaining nutrients. But the measurement may also contain lesser amounts of dissolved organic matter. Water can easily pick up impurities from natural and man-madesources because it is such an efficient solvent. Natural sources of TDS in drinking water include mineral springs, carbonate deposits, salt deposits, and sea water intrusion. Other sources can include sewage, urban and agricultural run-off, industrial wastewater, chemicals used in the water treatment process, the piping or hardware used to distribute the water, salts used for road de-icing, anti-skid materials, and more.
The indicator test for this drinking water contaminant is done to determine the general quality of the water. The TDS test only provides a qualitative measure of the amount of dissolved ions, but it does not provide information about specific dissolved ions. Other indicators of high TDS are hardness, scale formation, bitter taste in drinking water caused by calcium carbonate (CaCO3) and magnesium carbonate (MGCO3), and salty or brackish taste resulting from sodium chloride (NaCl) and potassium chloride (KCl). The latter can increase the corrosive ability of water. High TDS levels are also responsible for leaving water spots on dishes and white mineral buildup on water faucets and swamp coolers. It can also affect the efficiency of hot water heaters.
The indicator test for this drinking water contaminant is done to determine the general quality of the water. The TDS test only provides a qualitative measure of the amount of dissolved ions, but it does not provide information about specific dissolved ions. Other indicators of high TDS are hardness, scale formation, bitter taste in drinking water caused by calcium carbonate (CaCO3) and magnesium carbonate (MGCO3), and salty or brackish taste resulting from sodium chloride (NaCl) and potassium chloride (KCl). The latter can increase the corrosive ability of water. High TDS levels are also responsible for leaving water spots on dishes and white mineral buildup on water faucets and swamp coolers. It can also affect the efficiency of hot water heaters.
Fluoride may be an essential element for animals and humans. For humans, however, the essentiality has not been demonstrated unequivocally, and no data indicating the minimum nutritional requirement are available. To produce signs of acute fluoride intoxication, minimum oral doses of at least 1 mg of fluoride per kg of body weight were required. Many epidemiological studies of possible adverse effects of the long-term ingestion of fluoride via drinking-water have been carried out. These studies clearly establish that fluoride primarily produces effects on skeletal tissues (bones and teeth). Low concentrations provide protection against dental caries, especially in children. The pre- and post-eruptive protective effects of fluoride (involving the incorporation of fluoride into the matrix of the tooth during its formation, the development of shallower tooth grooves, which are consequently less prone to decay, and surface contact with enamel) increase with concentration up to about 2 mg of fluoride per litre of drinking-water; the minimum concentration of fluoride in drinking-water required to produce it is approximately 0.5 mg/litre.
However, fluoride can also have an adverse effect on tooth enamel and may give rise to mild dental fluorosis (prevalence: 12-33%) at drinking-water concentrations between 0.9 and 1.2 mg/litre (Dean, 1942); the period of greatest susceptibility is at the time of mineralization of the secondary upper central incis or teeth at about 22-26 months of age.. This has been confirmed in numerous subsequent studies, including a recent large-scale survey carried out in China (Chen et al., 1988), which showed that, with drinking-water containing 1 mg of fluoride per litre, dental fluorosis was detectable in 46% of the population examined. The extent of exposure from food was not clear in these studies. In general, dental fluorosis does not occur in temperate areas at concentrations below 1.5-2 mg of fluoride per litre of drinking-water. In warmer areas, because of the greater amounts of water consumed, dental fluorosis can occur at lower concentrations in the drinking-water. It is possible that in areas where fluoride intake via routes other than drinking-water (e.g., air, food) is elevated, dental fluorosis will develop at concentrations in drinking-water below 1.5 mg/litre.
However, fluoride can also have an adverse effect on tooth enamel and may give rise to mild dental fluorosis (prevalence: 12-33%) at drinking-water concentrations between 0.9 and 1.2 mg/litre (Dean, 1942); the period of greatest susceptibility is at the time of mineralization of the secondary upper central incis or teeth at about 22-26 months of age.. This has been confirmed in numerous subsequent studies, including a recent large-scale survey carried out in China (Chen et al., 1988), which showed that, with drinking-water containing 1 mg of fluoride per litre, dental fluorosis was detectable in 46% of the population examined. The extent of exposure from food was not clear in these studies. In general, dental fluorosis does not occur in temperate areas at concentrations below 1.5-2 mg of fluoride per litre of drinking-water. In warmer areas, because of the greater amounts of water consumed, dental fluorosis can occur at lower concentrations in the drinking-water. It is possible that in areas where fluoride intake via routes other than drinking-water (e.g., air, food) is elevated, dental fluorosis will develop at concentrations in drinking-water below 1.5 mg/litre.
Fluoride may be an essential element for animals and humans. For humans, however, the essentiality has not been demonstrated unequivocally, and no data indicating the minimum nutritional requirement are available. To produce signs of acute fluoride intoxication, minimum oral doses of at least 1 mg of fluoride per kg of body weight were required. Many epidemiological studies of possible adverse effects of the long-term ingestion of fluoride via drinking-water have been carried out. These studies clearly establish that fluoride primarily produces effects on skeletal tissues (bones and teeth). Low concentrations provide protection against dental caries, especially in children. The pre- and post-eruptive protective effects of fluoride (involving the incorporation of fluoride into the matrix of the tooth during its formation, the development of shallower tooth grooves, which are consequently less prone to decay, and surface contact with enamel) increase with concentration up to about 2 mg of fluoride per litre of drinking-water; the minimum concentration of fluoride in drinking-water required to produce it is approximately 0.5 mg/litre.
However, fluoride can also have an adverse effect on tooth enamel and may give rise to mild dental fluorosis (prevalence: 12-33%) at drinking-water concentrations between 0.9 and 1.2 mg/litre (Dean, 1942); the period of greatest susceptibility is at the time of mineralization of the secondary upper central incis or teeth at about 22-26 months of age.. This has been confirmed in numerous subsequent studies, including a recent large-scale survey carried out in China (Chen et al., 1988), which showed that, with drinking-water containing 1 mg of fluoride per litre, dental fluorosis was detectable in 46% of the population examined. The extent of exposure from food was not clear in these studies. In general, dental fluorosis does not occur in temperate areas at concentrations below 1.5-2 mg of fluoride per litre of drinking-water. In warmer areas, because of the greater amounts of water consumed, dental fluorosis can occur at lower concentrations in the drinking-water. It is possible that in areas where fluoride intake via routes other than drinking-water (e.g., air, food) is elevated, dental fluorosis will develop at concentrations in drinking-water below 1.5 mg/litre.
However, fluoride can also have an adverse effect on tooth enamel and may give rise to mild dental fluorosis (prevalence: 12-33%) at drinking-water concentrations between 0.9 and 1.2 mg/litre (Dean, 1942); the period of greatest susceptibility is at the time of mineralization of the secondary upper central incis or teeth at about 22-26 months of age.. This has been confirmed in numerous subsequent studies, including a recent large-scale survey carried out in China (Chen et al., 1988), which showed that, with drinking-water containing 1 mg of fluoride per litre, dental fluorosis was detectable in 46% of the population examined. The extent of exposure from food was not clear in these studies. In general, dental fluorosis does not occur in temperate areas at concentrations below 1.5-2 mg of fluoride per litre of drinking-water. In warmer areas, because of the greater amounts of water consumed, dental fluorosis can occur at lower concentrations in the drinking-water. It is possible that in areas where fluoride intake via routes other than drinking-water (e.g., air, food) is elevated, dental fluorosis will develop at concentrations in drinking-water below 1.5 mg/litre.