The presence of lead in drinking water is more prevalent and serious than many people realize. Despite common perceptions, lead is not restricted to inner-city communities, but rather is a problem that affects many water systems across the country. According to an Environmental Protection Agency study released in 1993, more than 800 drinking water systems around the nation contain excessive lead. Today, the EPA estimates that more than 40 million Americans are exposed to potentially dangerous amounts of lead in their drinking water.Recent legislation has helped decrease the problem.
In1991, the EPA imposed new standards for lead levels in drinking water that are 10 times more protective than levels previously thought to be safe. The new standard allows for a lead level of no more than 15 parts per billion (ppb). Current studies, however, show that lead levels in our drinking water continue to be too high. What's more, new research indicates that lead may be more harmful than previously thought.
Bacteria are the most numerous organisms on the planet. There are literally millions of different types of bacteria. They are one-celled organisms and are present in everything from water to food, and on objects we touch every day. What's ironic about bacteria is that they are among the smallest organisms on earth, and yet, they can cause some of the greatest problems. We come in contact with millions of bacteria every day, and nearly all are harmless. However, some types of bacteria are very harmful, especially those from sewage, even when present in small amounts.
Bacteria are the cause of some serious diseases, such as cholera, that plagued villages and towns centuries ago. Thanks to modem sanitation methods, many of these diseases have been greatly reduced or eliminated in the United States. Unfortunately, less developed countries that do not have effective sanitation systems are still affected by diseases caused by bacteria and viruses from sewage.
Most people develop an immunity to common bacteria at an early age. However, people with damaged or undeveloped immune systems, such as newborns, the elderly, AIDS patients, and cancer patients undergoing chemotherapy, are less resistant to disease and are more apt to become sick as a result of bacterial infections. Bacteria found in drinking water come from several sources. The most common source is the soil surrounding the water system. Once inside the system, these soil bacteria colonize every available surface, where they grow and then continually slough off into the water thereafter. In addition, bacteria can get into water during construction and repair of water lines, and through cracks in pipes when water pressure fluctuates. Municipal water systems check for harmful bacteria levels on a regular basis. Since it is impractical to test for all bacteria, they test instead for the main sewage organism, called E. coli. If E. coli is present in water, it means that harmful sewage contamination has occurred. Larger water municipalities conduct this test many times each day.
Bacteria can be described as either pathogenic or non-pathogenic, meaning whether or not they can cause disease. Pathogenic bacteria can overcome the body's natural defenses and invade healthy tissues. In addition, "opportunistic" or "secondary" pathogens are those that can cause an infection when an unusual opportunity, such as an open wound or suppressed immune system, presents itself. Very few types of bacteria are pathogenic.
Drinking Water Quality
All water utilities should deliver to the consumer an adequate supply of high-quality drinking water at a cost commensurate with the needs of each individual water system. To achieve this objective, the water should come from the highest quality source of supply available and be appropriately treated to meet regulatory and water supply industry criteria. Drinking water quality criteria should be based on documented health effects research, consumer acceptance, demonstrated treatment techniques, and effective utility management. The minimum criteria should be as defined by federal, state, and provincial regulations that take into account appropriate health and cost considerations.
High-quality water is defined as water that contains no pathogenic organisms and is free from biological forms that may be aesthetically objectionable. It is clear and colorless, and has no objectionable taste or odor. It does not contain concentrations of chemicals that may be physiologically harmful, aesthetically objectionable, or economically damaging. It also is not corrosive, nor does it leave excessive or undesirable deposits on water-conveying structures, including pipes, tanks, and plumbing fixtures.
Criteria used to evaluate the safety of drinking water are continually reassessed as new constituents are identified and health effects research advances. Regulatory agencies are developing standards and recommendations for contaminant levels in drinking water. Concurrently, the water supply industry is developing new and improved operation and treatment techniques to respond to the changing criteria. Drinking water quality criteria must consider all factors that affect the quality of water, the public health significance of the constituents, and the available technology to treat water.
The factors must recognize the practical aspects of design and operation and the capital cost of meeting the quality criteria. Establishing appropriate criteria, therefore, requires the combined efforts of regulatory agencies, consumers, and the water supply industry. Water resources are not geographically located to meet society's ever changing needs. Therefore, protection and enhancement of available surface water and groundwater supplies should be a North American priority to facilitate the effectiveness of economical production of safe, adequate, and aesthetically acceptable water for domestic use. Past waste disposal practices, urbanization, and effects of some modern technology have produced negative environmental effects on water sources. Long-term health effects related to certain chemicals, organisms, and environmental conditions are not fully known. Efforts to address these effects should include governments at all levels as well as public water suppliers. The program should include water quality operating guidelines defining high-quality water. Also included should be regulatory standards that define safe water.
Water quality operating guidelines must be comprehensive and balanced. They must be responsive to regulatory requirements and suitable for implementation. They must account for selection, protection, and management of the highest-quality source of supply. They must consider proper operation of the facilities that treat and distribute water to the consumers.
Water programs should include a comprehensive water quality control plan with at least the following aspects:
¥resource development and management.
¥Adequate quantities of high-quality water should be reserved for future needs.
¥watershed protection. Surface water and groundwater should be protected through control of waste disposal and restricted land use.
¥water quality operating levels. Criteria should define appropriate, acceptable constituent levels that are reasonably
¥achievable under most conditions.
¥end-product standards. Development should include regulatory standards for health-related constituents and
¥recommended standards for constituents not related to health.
The local water utility program should include a water quality control response plan for all appropriate constituents of concern. In some cases, no regulatory standard has been set for these constituents. In other cases, a reasonable time would be required to modify system design and operational procedures to comply with changes in regulatory requirements that may occur.
The local utility program should include establishment of system baseline data for future use by the utility. This information about source of supply, facilities, and operations can assist in the identification of conditions that prevent the utility from achieving compliance with water quality criteria.
Health-based regulatory criteria, water quality goals, and a current assessment of appropriate operating levels are necessary to identify good-quality water. The goals and recommended operating levels encompass the regulatory standards that are based on evaluation of health effects research, risk assessments, and risk management approaches. Because there are regional resource and size differences that affect the ability of water utilities to provide an adequate quality and quantity of water supply, the achievement of recommended operating levels must be reasonably evaluated.