Water treatment plant design fifth edition pdf free download

The recommended location of a storage tank is just beyond the center of demand in the service area AWWA, Elevated tanks are used most frequently, but other types of tanks and reservoirs include in-ground tanks and open or closed reservoirs. Common tank materials include concrete and steel. An issue that has drawn a great deal of interest is the problem of low water turnover in these facilities resulting in long detention times.

Much of the water volume in storage tanks is dedicated to fire protection, and unless utilities properly manage their tanks to control water quality, there can be problems attributable to both water aging and inadequate water mixing. Excessive water age can be conducive to depletion of the disinfectant residual, leading to biofilm growth, other biological changes in the water including nitrification, and the emergence of taste and odor problems.

Improper mixing can lead to stratification and large stagnant dead zones within the bulk water volume that have depleted disinfectant residual. As discussed later in this report, neither historical designs nor operational procedures have adequately maintained high water quality in storage tanks Clark et al.

Security is an important issue with both storage tanks and pumps because of their potential use as a point of entry for deliberate contamination of distribution systems.

Pumps are used to impart energy to the water in order to boost it to higher elevations or to increase pressure. Pumps are typically made from steel or cast iron. The cost of power for pumping constitutes one of the major operating costs for a water supply. The two types of valves generally utilized in a water distribution system are isolation valves or stop or shutoff valves and control valves. Isolation valves typically either gate valves or butterfly valves are used to isolate sections for maintenance and repair and are located so that the areas isolated will cause a minimum of inconvenience to other service areas.

Maintenance of the valves is one of the major activities carried out by a utility. Many utilities have a regular valve-turning program in which a percentage of the valves are opened and closed on a regular basis.

It is desirable to turn each valve in the system at least once per year. The implementation of such a program ensures that water can be shut off or diverted when needed, especially during an emergency, and that valves have not been inadvertently closed. Control valves are used to control the flow or pressure in a distribution system.

They are normally sized based on the desired maximum and minimum flow rates, the upstream and downstream pressure differentials, and the flow velocities. Typical types of control valves include pressure-reducing, pressure-sustaining, and pressure-relief valves; flow-control valves; throttling valves; float valves; and check valves. Most valves are either steel or cast iron, although those found in premise plumbing to allow for easy shut-off in the event of repairs are usually brass. They exist throughout the distribution system and are more widely spaced in the transmission mains compared to the smaller-diameter pipes.

Blow-off valves are sometimes located near dead ends where water can. Care must be taken at these locations to prevent unprotected connections to sanitary or storm sewers. Hydrants are primarily part of the fire fighting aspect of a water system. Proper design, spacing, and maintenance are needed to insure an adequate flow to satisfy fire-fighting requirements.

Fire hydrants are typically exercised and tested annually by water utility or fire department personnel. Fire flow tests are conducted periodically to satisfy the requirements of the Insurance Services Office or as part of a water distribution system calibration program ISO, Fire hydrants are installed in areas that are easily accessible by fire fighters and are not obstacles to pedestrians and vehicles.

In addition to being used for fire fighting, hydrants are also for routine flushing programs, emergency flushing, preventive flushing, testing and corrective action, and for street cleaning and construction projects AWWA, The function of a water distribution system is to deliver water to all customers of the system in sufficient quantity for potable drinking water and fire protection purposes, at the appropriate pressure, with minimal loss, of safe and acceptable quality, and as economically as possible.

To convey water, pumps must provide working pressures, pipes must carry sufficient water, storage facilities must hold the water, and valves must open and close properly.

Indeed, the carrying capacity of a water distribution system is defined as its ability to supply adequate water quantity and maintain adequate pressure Male and Walski, Adequate pressure is defined in terms of the minimum and maximum design pressure supplied to customers under specific demand conditions. The maximum pressure is normally in the range of 80 to psi; for example, the Uniform Plumbing Code requires that water pressure not exceed 80 psi kPa at service connections, unless the service is provided with a pressure-reducing valve.

The minimum pressure during peak hours is typically in the range of 40 to 50 psi — kPa , while the recommended minimum pressure during fire flow is 20 psi kPa. Of the 34 billion gallons of water produced daily by public water systems in the United States, approximately 63 percent is used by residential customers for indoor and outdoor purposes. Mayer et al. Outdoor water use varies quite significantly from region to region and includes irrigation.

Of the indoor water use, less than 20 percent is for consumption or related activities, as shown below:. Most of the water supplied to residences is used primarily for laundering, showering, lawn watering, flushing toilets, or washing cars, and not for consumption. Nonetheless, except in a few rare circumstances, distribution systems are assumed to be designed and operated to provide water of a quality acceptable for human consumption.

Normal household use is generally in the range of gallons per day L per day with a typical flow rate of 2 to 20 gallons per minute gpm [7. Besides providing drinking water, a major function of most distribution systems is to provide adequate standby fire flow, the standards for which are governed by the National Fire Protection Association NFPA, Fire-flow requirements for a single family house vary from to 1, gpm 2,—5, Lpm ; for multi-family structures the values range from 2, to 5, gpm 7,—18, Lpm ; for commercial structures the values range from 2, to 10, gpm 7,—37, Lpm , and for industrial structures the values range from 3, to over 10, gpm 11,—37, Lpm AWWA, The duration for which these fire flows must be sustained normally ranges from three to eight hours.

In order to satisfy this need for adequate standby capacity and pressure, most distribution systems use standpipes, elevated tanks, and large storage reservoirs. The minimum flow that the water system can sustain for a specific period of time governs its fire protection rating, which then is used to set the fire insurance rates for the communities that are served by the system.

As a conse-. A study conducted by the American Water Works Association Research Foundation confirmed the impact of fire-flow capacity on the operation of, and the water quality in, drinking water networks Snyder et al. It found that although the amount of water used for fire fighting is generally a small percentage of the annual water consumed, the required rates of water delivery for fire fighting have a significant and quantifiable impact on the size of water mains, tank storage volumes, water age, and operating and maintenance costs.

Generally nearly 75 percent of the capacity of a typical drinking water distribution system is devoted to fire fighting Walski et al. The effect of designing and operating a system to maintain adequate fire flow and redundant capacity is that there are long transit times between the treatment plant and the consumer, which may be detrimental to meeting drinking water MCLs Clark and Grayman, ; Brandt et al.

Snyder et al. Water efficient fire suppression technologies exist that use less water than conventional standards. In particular, the universal application of automatic sprinkler systems provides the most proven method for reducing loss of life and property due to fire, while at the same time providing faster response to the fire and requiring significantly less water than conventional fire-fighting techniques.

There is a growing recognition that embedded designs in most urban areas have resulted in distribution systems that have long water residence times due to the large amounts of storage required for fire fighting capacity. More than ten years ago, Clark and Grayman expressed concern that long residence times resulting from excess capacity for fire fighting and other municipal uses would also provide optimum conditions for the formation of DBPs and the regrowth of microorganisms.

They hypothesized that eventually the drinking water industry would be in conflict over protecting public health and protecting public safety. Non-conventional water distribution system designs that might address some of these issues are discussed below including decentralized treatment, dual distribution systems, and an approach that utilizes enhanced treatment to solve distribution system water quality problems.

However, their potential future role in abating the problems discussed above warrants mention here and further consideration by EPA and water utilities. Usually, the distributed units provide advanced treatment to meet stringent water quality requirements at consumer endpoints that would otherwise be in violation. Distributed units would be located either at the point-of-entry of households, for example, or at a more upstream location from which different water use could be served.

This might be at the neighborhood or district level, depending on technological and financial requirements. How the decentralized treatment concept might be implemented in water systems worldwide is still at a theoretical stage e.

The approach largely views water supply, treatment, and waste disposal as different aspects of the same integrated system. Box describes the concepts in detail. DOT-Net is a decentralized treatment concept in which water supplies are segregated based on uses or use functions and levels of quality, to which a qualitative ranking on a scale of 1 to 10 is assigned, with 1 being the best quality and 10 the worst. The use functions include potable water, black water, gray water, various industrial discharges, etc.

For example, water extracted from a local surface water source might be given a rank of 6. Following centralized treatment, the water would have a rank of 2. There is then an assumption that this supply will be degraded in distribution systems to a level that is generally not acceptable as potable water say 3. To address this, advanced treatment technologies such as membranes and super-critical water treatment would be located as satellite systems close to the point of use, producing a water of ranking 1.

This concept hinges upon segregating water into the various use functions and developing and deploying the technology needed to bring about the desired water quality for each function. For example, water for drinking, showering, and cooking would require the highest level of quality and should be treated appropriately using satellite systems and advanced technologies. Advanced technologies exist for the treatment, analysis, and control of personal water including sophisticated electromechanical systems for rapid monitoring and feedback.

The existing distribution system would still be used, but would be supplemented with treatment units to treat a portion of the water supply. For example, satellite treatment units may be located in large buildings with a high population density or distributed over neighborhoods.

The concept extends to the waste streams generated by each type of water use, as shown in Figure Thus, advanced water treatment would be used not only prior to water delivery, but also upon water disposal but before it is discharged into a centralized collection system. For example if a certain commercial enterprise produced a highly degraded waste stream with a ranking of 10 , a satellite unit could be used to raise the quality to that of the other common waste streams say 7.

Such advanced and other wastewater treatment would be implemented in a manner to eventually resupply the source waters or to. The principal trade-off associated with utilizing such systems is the alternative cost associated with upgrading large centralized treatment facilities and distribution networks.

On a per person basis, it is less expensive to build one large treatment system than to build several small ones. In addition to these costs, multiple or new pipe networks are a necessary part of the design framework for these satellite systems.

That is, new piping would be needed from the advanced water treatment system into the household or industry , although it would travel a short distance and would be a small percentage of the total plumbing for the building. It is possible that investing in larger satellite systems with separate piping might offer a cost advantage compared to small satellite systems, based on economies of scale Norton, Clearly, there would have to be a policy to avoid social injustice such that decentralized treatment when implemented is affordable to the average user.

Also envisioned is the potential recovery of energy from the treatment of black water as well as some industrial sources. A second important consideration is the need to monitor the satellite systems, and whose responsibility that monitoring would be. Maintenance activities, such as repair and replacement of a new piping system associated with satellite treatment, would also have to be well planned in order to prevent contamination of the distribution system downstream of the treatment unit.

Incorporation of remote control technologies and other monitoring adaptations could reduce the need for human intervention while ensuring that the units operate satisfactorily. Currently only about 10 percent of the network is having trouble with compliance but it is anticipated as the system expands, more and more of the network will be out of compliance.

A third approach to slowing water quality deterioration involves centralized treatment options that can improve the quality of water to such a degree that formation of DBPs and loss of disinfectant residual are minimized. This approach is practiced by the Greater Cincinnati Water Works, which serves a large metropolitan area consisting of urban and suburban areas with potable water and fire flow protection.

During normal plant operation, between seven and 11 of these contactors are used in parallel to process water. Once GAC becomes spent, it is reactivated using an on-site reactivation system. Between and , Las Vegas grew faster than any other metropolitan area in the U. In , the service area population was , but by it had grown to 1,, Jacobsen and Kamojjala, The source of water is Lake Mead.

The treatment train at both plants is nearly identical, consisting of ozone and direct filtration. Chlorine is utilized as the final disinfectant. Coagulation dosages are limited and TOC removals through the biologically active filters range from 10 to 30 percent. The distribution system consists of 3, miles 5, km of pipe and 29 water storage reservoirs. The system experiences long residence times in some case greater than a week , resulting in an increase in water temperature as it moves through the system.

Consequently it is difficult to maintain chlorine residuals in some parts of the system, necessitating the addition of chlorine at many locations. Currently the system is in compliance with all Safe Drinking Water Act regulations. Advanced oxidation, granular activated carbon GAC adsorption, enhanced coagulation including addition of clarification , and nanofiltration were considered possible changes to treatment that could be helpful.

In addition, operational and residual disinfectant changes were considered such as conversion from free chlorine to chloramine and a reduction in distribution system detention time. It would provide a cost-effective approach by only treating water where needed at specific locations, instead of treating water for the entire system. It would reduce residuals production from treatment as compared to intensive organics removal.

And it would provide for the continuous use of chlorine and avoid potential nitrification problems. Las Vegas and Cincinnati have chosen distinctly different approaches to meeting and solving the residence time and excess capacity problem. The Las Vegas system is currently conducting studies to explore the possibility of applying treatment at various locations. Research is being conducted that would focus primarily on removing the precursor material in the water in order to keep the DBP formation potential below regulated limits.

A key aspect of this strategy is to use distribution system models and GIS technology to monitor residence time and DBP formation potential in the system.

Cincinnati, on the other hand, has chosen the more traditional but very effective approach of removing DBP precursor material prior to distribution and thereby minimizing the potential formation of DBPs throughout the system. Another option for design and operation of distribution systems is the creation of dual systems in which separate pipe networks are constructed for potable and nonpotable water. In these types of systems, reclaimed wastewater or water of sub-potable quality may be used for fire fighting and other special purposes such as irrigation of lawns, parks, roadway borders and medians; air conditioning and industrial cooling towers; stack gas scrubbing; industrial processing; toilet and urinal flushing; construction; cleansing and maintenance, including vehicle washing; scenic waters and fountains; and environmental and recreational purposes.

The design of these systems differentiates dual systems from most community water supplies, in which one distribution system provides potable water to serve all purposes.

Most dual systems in use today were installed by adding reclaimed water lines alongside but not connected to potable water lines already in place. For example, in St. Petersburg, Florida, a reclaimed water distribution system was placed into operation in , and fire protection is provided from both the potable and reclaimed water lines.

San Francisco has a nonpotable system, constructed after the earthquake, that serves the downtown area to augment fire protection. Rouse Hill, Australia was the first community to plan a dual water system with the reclaimed water lines to serve all nonpotable uses, including fire protection, such that the potable water line can have much smaller pipe diameters. Both the potable and nonpotable systems have service reservoirs for.

Dan Okun Okun, and Dr. Neil Grigg Grigg, a addressed the merits of dual distribution systems for U. The argument is that because existing water distribution systems are designed primarily for fire protection, the majority of the distribution system uses pipes that are much larger than would be needed if the water was intended only for personal use.

This leads to residence times of weeks in traditional systems versus potentially hours in a system comprised of much smaller pipes. In the absence of smaller sized distribution systems, utilities have had to implement flushing programs and use higher dosages of disinfectants to maintain water quality in distribution systems. Furthermore, large pipes are generally cement-lined or unlined ductile iron pipe typically with more than joints per mile.

These joints are frequently not water tight, leading to water losses as well as providing an opportunity for external contamination of finished water. From an engineering perspective it seems intuitively obvious that it is most efficient to satisfy all needs by installing one pipe and to minimize the number of pipe excavations.

This philosophy worked well in the early days of water system development. However, it has resulted in water systems with long residence times and their negative consequences under normal water use patterns and a major investment in above-ground pumps and storage tanks and below-ground transmission mains, distribution pipes, service connections, etc.

Therefore as suggested in Okun it may be time to look at alternatives for supplying the various water needs in urban areas such as dual distribution systems. The water reuse aspect of dual systems is particularly attractive in arid sections of the U. Although there are many examples of water reuse in the United States EPA, , not many of them involve the use of a dual distribution system.

The City of St. Petersburg, which operates one of the largest urban reuse systems in the world, provides reclaimed water to more then 7, residential homes and businesses. In Irving, Texas, advanced secondary treated wastewater and raw water from the Elk Fork of the Trinity River are used to irrigate golf courses, medians, and greenbelt areas, and to maintain water levels at the Las Colinas Development.

The reclaimed water originates from the A third example is provided in Hilton Head, South Carolina, where about 5 mgd. All of the wastewater treatment systems have been upgraded to tertiary systems, and an additional flow rate of the same size as the first is being planned. Perhaps the most famous water reuse operation using a dual distribution system is the Irvine Ranch Water District in Irvine, California see Box There is a recent trend in California toward the use of more dual distribution systems, particularly in new developments, as a result of statutory requirements to use reclaimed water in lieu of domestic water for non-potable uses California Water Code Section and because of the need to conserve water to meet increasing local and regional water demands.

The potential advantages of using dual distribution systems include the fact that much smaller volumes of water would need be treated to high standards, which would result in cost savings at the treatment plant if all water supplied were to be treated in this fashion. Another advantage is that flow in the potable line would be expected to be relatively constant compared to a traditional system where large quantities of water would need to be transferred over short time periods e.

The associated flow and pressure changes in a pipe carrying the total water needs for a community are expected to be much greater than in the potable line of a dual distribution system.

As discussed later in this document, there is evidence that pressure transients may result in intrusion of contaminated water. Furthermore, use of improved materials in the newer, smaller distribution system would minimize water degradation, loss, and intrusion.

However, the creation of dual distribution systems necessitates the retrofitting of an existing water supply system and reliance on existing pipes to provide non-potable supply obtained from wastewater or other sources.

Large costs would be incurred when installing the new, small diameter pipe for potable water, disconnecting the existing system from homes and other users so that it could be used reliably for only nonpotable needs, and other retrofitting measures.

These costs can be reduced if a new system is used only for reclaimed water distribution, as was done at Irvine Ranch, but this of course would not decrease the extent of quality degradation now experienced in existing systems.

It is also critical to differentiate between full and partial adoption of dual distribution systems, the latter of which has occurred in several cities.

For example, if a new nonpotable line is installed alongside an existing potable line, the nonpotable line can draw demand away from the potable line, thereby increasing its detention time and aggravating water quality deterioration in the potable line. Furthermore, if the potable system is still used for fire flow, which generally governs pipe sizing, many of the advantages of the dual system will not be realized. Dual systems may be most advantageous in new communities where neither type of distribution system currently exists.

New communities could better optimize their systems because both types of piping systems could be built simultaneously. The cost savings from the need to treat a much smaller portion of the total water to a higher quality could partially offset the costs of constructing two.

The Irvine Ranch Water District is one of the first water districts in the United States to practice wastewater reuse. It serves , people over square miles There are 85, domestic connections and 3, recycled connections.

As of , there are 1, miles 1, m of pipe for the potable system. As part of the potable system, there are 28 above-ground and below-ground storage tanks that range in volume from 0. The most unusual aspect of the District system is the recycled reclaimed water network. There are miles Domestic water tanks sit side by side with reclaimed water tanks.

The recycled water is used only for toilet flushing in a few high-rise buildings, for cooling towers, for landscape irrigation especially at golf courses and condominium complexes, for food crops, and by one carpet manufacturer. Recycled water for toilet flushing is not used in residences, only in businesses.

Recycled water itself is tertiary treated wastewater. It meets all of the water quality standards for drinking water, but it is high in salt. Interestingly, in the summer the recycled water has a much lower retention time in the distribution system than the potable water because of greater demand for the recycled water for landscaping.

However, when the demand for recycled water is less than the input from WWTPs, the recycled water is put it in long-term storage. Indeed, one of the reasons dual systems were installed in high rises and other buildings was to make demand for recycled water more level throughout the year. There are no hydrants on the recycled system, so the reclaimed water is not used for fighting fires, and the pipe sizes in the recycled system are generally smaller than in the potable system.

Chloramine provides residual disinfection in the potable system but chlorine is used in the recycled system as mandated by California regulations. The SCADA system, which consists of 6, sampling points, provides minute-by-minute monitoring of chlorine residuals in the recycled system.

Special purpose monitoring includes a nitrification action plan that requires tank sampling. Internal requirements include bi-monthly sampling of conductivity, turbidity, color, pH, chlorine residual, total coliform, and fecal coliform and total suspended solids at special locations.

The water uses for the recycled water are very specific, and it is the goal of the utility to make sure the water is of an acceptable quality for those uses. Domestic potable water costs are 64 cents per thousand gallons for domestic water and 59 cents per thousand gallons for recycled water.

There are approximately 13, CCC devices in place throughout the system. The District conducts an annual cross-connection shut-down test for the recycled irrigation water, and only one cross connection has been found in the last 10 years.

For backflow prevention, a reduced pressure principle assembly at the meter is used, as required by the state of CA. Additional devices are installed if found to be needed. Clearly, better understanding the technological potential and economic consequences of dual distribution systems is an important research goal.

Non-traditional options for drinking water provision present many unanswered questions but few case studies from which to gather information. The primary concerns include determining their economic feasibility and the existence of unknown costs, developing a plan for transition and implementation which are expected to be very significant undertakings in existing communities , and maintenance of quality assurance and quality control in systems that would be potentially much more complicated than the current system.

Furthermore, it is not clear how alternative distribution system designs will affect water security, an important consideration since September 11, The potential for cross connections or misuse of water supplies of lesser quality is greatly increased in dual distribution systems and decentralized treatment.

Larger-scale questions involve potential social inequities and the extent to which nontraditional approaches will transfer costs to the consumer. These issues will have to be considered carefully in communities that decide to adopt these new designs for water provision. The previous discussion raises a number of research issues, some of which are already noted.

With regard to the influence of fire fighting requirements, distribution systems are frequently designed to supply water to meet maximum day demand and fire flow requirements simultaneously. This affects minimum pipe diameters, minimum system pressures under maximum day plus fire flow demand , fire hydrant spacing, valve placement, and water storage.

Generally, agencies that set fire flow requirements are not concerned about water quality while drinking water utilities must be concerned about both quality and fire flow capacity. It will be important to better evaluate the effectiveness of alternative fire suppression technologies including automatic sprinkler systems in a wide range of building types, including residences.

Such systems have rarely been evaluated for their positive and negative features with respect to water quality. Furthermore, if fire suppression technologies were improved, it might be possible to rely on smaller sized pipes in distribution systems, as is being tested in Europe Snyder et al.

If alternatives such as satellite systems and dual systems are not used, continued efforts will be required to upgrade existing distribution systems and to treat water to acceptable levels of quality, so that quality does not deteriorate during distribution.

The balance of this report is focused on traditional distribution system design, in which water originates from a centralized treatment plant or well and is then distributed through one pipe network to consumers.

Nonetheless, many of the report recommendations are relevant even if an alternative distribution system design is used. Water utilities in the United States vary greatly in size, ownership, and type of operation. The SDWA defines public water systems as consisting of community water supply systems; transient, non-community water supply systems; and non-transient, non-community water supply systems.

A community water supply system serves year-round residents and ranges in size from those that serve as few as 25 people to those that serve several million. A transient, non-community water supply system serves areas such as campgrounds or gas stations where people do not remain for long periods of time. You can create one as well, really easily. Get started. Flipsnack can also be used as: online design tool , magazine maker , brochure creator , catalog maker , portfolio maker , flipbook maker.

If you want to learn more about the cookies we're using, make sure to check our Cookie policy Essentials. Always active. Your local water authority is always your first source for testing and identifying lead contamination in your tap water. Many public water authorities have websites that include data on drinking water quality, including results of lead testing.

EPA requires all community water systems to prepare and deliver an annual water quality report called a Consumer Confidence Report CCR for their customers by July 1 of each year. Contact your water utility if you'd like to receive a copy of their latest report.

If your water comes from a household well or other private water supply, check with your health department, or with any nearby water utilities that use ground water, for information on contaminants of concern in your area. EPA's Public Notification Rule requires public water systems to alert you if there is a problem with your drinking water. Homes may have internal plumbing materials containing lead. Since you cannot see, taste, or smell lead dissolved in water, testing is the only sure way of telling whether there are harmful quantities of lead in your drinking water.

A list of certified laboratories are available from your state or local drinking water authority. Contact your water supplier as they may have useful information, including whether the service connector used in your home or area is made of lead. You can also view and print a fact sheet on testing your home's drinking water. Protect Your Tap: A quick check for lead is an on-line step by step guide to learn how to find lead pipes, called service lines, in your home.

It also provides tips about reducing exposure to lead in drinking water and how to get your water tested for lead and resources to learn more. You can learn about how this guide was developed and toolkits for sharing with others on the Protect Your Tap outreach page. Tool kits for different sectors with resources to create your own campaign to get others to use Protect Your Tap:. A family doctor or pediatrician can perform a blood test for lead and provide information about the health effects of lead.

State, city or county departments of health can also provide information about how you can have your child's blood tested for lead. Children spend a significant part of their days at school or in a child care facility. The faucets that provide water used for consumption, including drinking, cooking lunch, and preparing juice and infant formula, should be tested.

This law requires EPA to determine the level of contaminants in drinking water at which no adverse health effects are likely to occur with an adequate margin of safety. These non-enforceable health goals, based solely on possible health risks are called maximum contaminant level goals MCLGs. The MCLG for lead is zero. EPA has set this level based on the best available science which shows there is no safe level of exposure to lead.

The fact that there is no safe level of exposure underscores the fact that any action to reduce exposures can have impacts on lives and livelihoods.

For most contaminants, EPA sets an enforceable regulation called a maximum contaminant level maximum contaminant level The highest level of a contaminant that EPA allows in drinking water. MCLs ensure that drinking water does not pose either a short-term or long-term health risk. MCLs are set as close to the MCLGs as possible, considering cost, benefits and the ability of public water systems to detect and remove contaminants using suitable treatment technologies.

However, because lead contamination of drinking water often results from corrosion of the plumbing materials belonging to water system customers, EPA established a treatment technique rather than an MCL for lead.