8
Alternatives for Premise Plumbing

Premise plumbing includes that portion of the potable water distribution system associated with schools, hospitals, public and private housing, and other buildings. It is connected to the main distribution system via the service line. The quality of potable water in premise plumbing is not ensured or monitored by U.S. Environmental Protection Agency (EPA) regulation. Indeed, the only Safe Drinking Water Act (SDWA) rule in which drinking water quality is purposefully measured within premise plumbing is the Lead and Copper Rule (LCR) for which samples are collected at the tap after the water has been allowed to remain stagnant.

Virtually every problem previously identified in the main water transmission system can also occur in premise plumbing. However, unique characteristics of premise plumbing can magnify the potential public health risk relative to the main distribution system and complicate formulation of coherent strategies to deal with problems. This chapter discusses these characteristics and then considers both technical issues such as the need for monitoring of premise plumbing condition and policy alternatives for controlling public health issues related to premise plumbing.

KEY CHARACTERISTICS OF PREMISE PLUMBING

Premise plumbing systems have noteworthy differences from the main distribution system that are often under-appreciated by scientists and regulators with respect to public health goals. These are summarized in Table 8-1 and discussed more comprehensively below.


High Surface Area to Volume Ratio. Premise plumbing is characterized by relatively lengthy sections of small-diameter tubing. The total pipe length of the main distribution system has been estimated at about 1 million miles (Brongers et al., 2002; Grigg, 2005), whereas 5.3 million miles of copper tubing alone were installed in buildings between 1963 and 1999 (CDA, 2005). Premise plumbing has about ten times more surface area per unit length than in the main distribution system. One study of a distribution system in Columbia, Missouri determined that household plumbing and service connections had 82 percent of the total pipe length, 24 percent of the total surface area in the distribution system, and held just 1.6 percent of the total volume of water in the system (Brazos et al., 1985). Another 10 percent of the total distribution system volume was in premise plumbing if toilets and water heaters were considered (Brazos et al., 1985).



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Drinking Water Distribution Systems: Assessing and Reducing Risks 8 Alternatives for Premise Plumbing Premise plumbing includes that portion of the potable water distribution system associated with schools, hospitals, public and private housing, and other buildings. It is connected to the main distribution system via the service line. The quality of potable water in premise plumbing is not ensured or monitored by U.S. Environmental Protection Agency (EPA) regulation. Indeed, the only Safe Drinking Water Act (SDWA) rule in which drinking water quality is purposefully measured within premise plumbing is the Lead and Copper Rule (LCR) for which samples are collected at the tap after the water has been allowed to remain stagnant. Virtually every problem previously identified in the main water transmission system can also occur in premise plumbing. However, unique characteristics of premise plumbing can magnify the potential public health risk relative to the main distribution system and complicate formulation of coherent strategies to deal with problems. This chapter discusses these characteristics and then considers both technical issues such as the need for monitoring of premise plumbing condition and policy alternatives for controlling public health issues related to premise plumbing. KEY CHARACTERISTICS OF PREMISE PLUMBING Premise plumbing systems have noteworthy differences from the main distribution system that are often under-appreciated by scientists and regulators with respect to public health goals. These are summarized in Table 8-1 and discussed more comprehensively below. High Surface Area to Volume Ratio. Premise plumbing is characterized by relatively lengthy sections of small-diameter tubing. The total pipe length of the main distribution system has been estimated at about 1 million miles (Brongers et al., 2002; Grigg, 2005), whereas 5.3 million miles of copper tubing alone were installed in buildings between 1963 and 1999 (CDA, 2005). Premise plumbing has about ten times more surface area per unit length than in the main distribution system. One study of a distribution system in Columbia, Missouri determined that household plumbing and service connections had 82 percent of the total pipe length, 24 percent of the total surface area in the distribution system, and held just 1.6 percent of the total volume of water in the system (Brazos et al., 1985). Another 10 percent of the total distribution system volume was in premise plumbing if toilets and water heaters were considered (Brazos et al., 1985).

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Drinking Water Distribution Systems: Assessing and Reducing Risks TABLE 8-1 Characteristics of U.S. Public and Private Transmission Systems Characteristic Public Infrastructure Private Infrastructure Approx. Pipe Surface per Volume Water* 0.26 cm2/mL* 2.1 cm2/mL* Total Pipe Length (U.S.) 0.97 million miles > 6 million miles Replacement Value $0.6 trillion Much greater than $0.6 trillion Prediction of Failure Events Statistically predictable Unpredictable for individual homeowner Property Damage ($/consumer) Relatively low Potentially very high Common Pipe Material Cement, ductile iron, plastic, cast iron Copper, plastics, galvanized iron, stainless steel, brass Stagnation Relatively rare except dead ends Frequent and of variable length Disinfectant Residual Almost always present Frequently absent Regrowth Potential Rarely realized (partly because rarely measured) Frequently realized Pipe Wall Thickness > 6.6 mm 0.71–1.7 mm for copper tube Velocity 2 to 6 ft/sec Can be > 33 ft/sec, on/off or continuous Infiltration Abrupt changes in flow are relatively controllable (e.g., via scheduled flushing, proper distribution system design) The service line can be the point of minimum pressure and experience frequent water hammer, the highest velocities, and the most leaks Temperature 0–30° C 0–100° C (at the surface of heating elements) Control of Water Quality Utility treatments and operation No control over water coming into home, but home treatment devices and selection of plumbing materials can influence water quality Ownership Utility End user Maximum Cost over 30 Years per Consumer $500–$7,000 US As much as $25,000 per homeowner, frequency determined by lifetime of plumbing Financial Responsibility Distributed burden over time and large customer base Individual consumer Cross Connections Relatively rare Widely prevalent Frequency of Sample Collection and Evaluation of WQ Degradation Regular sampling required by regulation and industry best standards Often sampled only in reactive mode to consumer complaints *Based on a 15.2-cm diameter for mains and 1.9-cm diameter for home plumbing. SOURCE: Reprinted, with permission, from Edwards et al. (2003). © 2003 by Marc Edwards.

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Drinking Water Distribution Systems: Assessing and Reducing Risks Water Age. Utilities and consumers have little control over water age in consumer plumbing. Water can sit stagnant in some buildings for extended periods if they are irregularly occupied, as exemplified by schools in summer months, vacation homes, or residences whose occupants have work that requires frequent prolonged travel. Even under full-time occupancy, some sections of plumbing within a given building are rarely used, and flow patterns can be highly variable dependent on water use patterns of the occupants. The upshot is that premise plumbing adds a layer of complexity to the hydraulics of distribution systems (see Chapter 5). That is, water residing in a given premise will have a wider distribution of water age than water at the entrance to the premise, resulting in greater variation in disinfectant residual levels, bacterial regrowth, and other issues than occurs in the main distribution system. It should be noted that the negative effects of water age are exacerbated if the biological stability of the finished water is poor. Viable strategies to prevent problematic regrowth include local codes mandating premise plumbing materials that do not quickly react with disinfectants, removal of nutrients from the water to minimize regrowth potential when the disinfectant does disappear, recommendations that consumers flush unused premise plumbing lines, installation of booster stations (e.g., as is sometimes done in hospital plumbing systems) to ensure that residuals are supplied to all points of the distribution system, and use of on-demand water heaters to minimize storage volumes in premises. Presence of Different Materials. Premise plumbing systems are comprised of a wide range of materials including copper, plastics, brass, lead, galvanized iron, and occasionally stainless steel. Many of these materials are not typically present in the main distribution system. The impact of water quality changes on the performance of materials within premises, and the effects of materials on water quality within premises, are often overlooked by water utilities. For instance, Brazos et al. (1985) show that the majority of chlorine demand in water systems often arises from pipe surfaces. Extensive work has been done investigating the reactions between chlorine and materials used in the main distribution system including polyethylene, PVC, iron, and cement (e.g., Clark et al., 1994), and routine samples collected in distribution systems reflect disinfectant loss from reaction with these materials. In general, reaction rates for chloramine with materials in the main transmission system are very low compared to free chlorine. But recent research has demonstrated that under at least some circumstances, chlorine and monochloramine decay very rapidly via reactions with copper and brass in premise plumbing (Powers, 2000; Nguyen, 2005; Nguyen and Edwards, 2005). Domestic water heaters also have very reactive aluminum and magnesium anodes that can contribute to rapid chlorine and chloramine decay in buildings. Extreme Temperatures. Water sitting in premise plumbing is subject to greater extremes of temperature than in the main distribution system (Rushing and Edwards, 2004). In summer months, even the cold water line in premise

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Drinking Water Distribution Systems: Assessing and Reducing Risks plumbing can be 10–15° C warmer than for the mains. In addition, there is a hot-water distribution system with storage in most buildings, and often water chillers or refrigerated lines. The sampling of the main distribution system cannot capture effects of these variations on water quality in premise plumbing, particularly in relation to microbial type and concentrations. This is especially true for moderate thermophiles such as Legionella in water heaters. Low or No Disinfectant Residual. Due to the high surface area to volume ratio, presence of reactive materials such as copper, long storage times, and warmer temperatures in premise plumbing, it is not possible to continuously maintain residual disinfectant throughout premise plumbing systems. Continuous contact with the water heater and copper pipe in hot water recirculation systems may be especially problematic with respect to maintaining chlorine residuals. Furthermore, water treatment devices are often installed by homeowners to remove tastes and odors—devices that also remove the disinfectant from the water. Figure 8-1 shows how the residual detected in hot water in Philadelphia residences during random sampling was well below the average disinfectant residual found in the main distribution system, even when chloramine, which is more persistent than chlorine, is used. The observed variability in disinfectant residual in homes would not be detected by a routine monitoring program for regulatory compliance; it is due to factors such as variability in water temperature, retention time in water heaters, condition of internal materials, type of heaters and pipes, etc. FIGURE 8-1 Water quality test results for hot water in 27 customer homes in Philadelphia. The average chloramine residual throughout the distribution system was 1.73 mg/L during December, 2003. At this time of year, chloramine decay rates in this distribution system are very low, such that the observed decreases in residual occurred primarily in premise plumbing.

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Drinking Water Distribution Systems: Assessing and Reducing Risks Rapid chloramine decay within cold water copper pipe in consumers’ homes has also been observed (Murphy et al., 1997a,b), and the resulting growth of nitrifiers can influence lead and copper leaching to water due to lowered pHs and other impacts (Garret, 1891; AWWA, 2003; Edwards and Dudi, 2004). In other instances that the committee is familiar with, chloramine has not been found to decay rapidly in premise plumbing, so additional research is needed to determine the prevalence and specifics of the problem. Bacterial Levels and Potential for Regrowth. The lack of persistent disinfectant residuals, high surface area, long stagnation times, and warmer temperatures can make premise plumbing very suitable for microbial regrowth in at least some circumstances. Typical distribution system monitoring stipulates thoroughly flushing water through premise plumbing when sampled; consequently, problems with regrowth in premise plumbing systems can be missed. Brazos et al. (1985) noted a two- to three-order of magnitude increase in bacteria after water was held stagnant in home plumbing versus levels obtained in the same water after flushing. Using the same basic protocol in two systems experiencing difficulties with microbial control, Edwards et al. (2005) found a five-log increase in bacteria during stagnation in premise plumbing systems in Maui, Hawaii, and a three-log increase in Washington, DC. It is undoubtedly the case that high levels of bacteria in first draw samples are sometimes due to regrowth of bacteria in the faucet aerator (LeChevallier and Seidler, 1980). However, the Edwards et al. (2005) study was supplemented by bench-scale results that reproduced the problem without a faucet present. On the basis of their monitoring results, Brazos et al. (1985) recommended monitoring for bacteria in first draw samples in addition to routine monitoring of bacteria in the main transmission system. To date there is little direct evidence that high levels of heterotrophic bacteria in premise plumbing systems have adverse health effects. However, opportunistic pathogens such as Legionella spp. and nontuberculous Mycobacterium spp. have been found in the biofilms of premise plumbing systems (Pryor et al., 2004; Tobin-D’Angelo et al., 2004; Vacrewijck et al., 2005; Flannery et al., 2006; Thomas et al., 2006; Tsitko et al., 2006). Hot-water storage tanks and showerheads may permit the amplification of these bacteria. As discussed in Chapter 3, outbreaks in healthcare facilities of Legionnaire’s disease have been attributed to Legionella pneumophila in hot water tanks and showerheads. There is some evidence that nontuberculous mycobacteria may colonize biofilms, and the species found in treated drinking water have been linked to infections in immunocompromised individuals. Highly Variable Velocities. Premise plumbing is characterized by start–stop flow patterns that can scour scale and biofilms from pipe surfaces. Flows up to 10 meters per second can occur. This makes premise plumbing more susceptible to the dislodgement of biofilms and associated negative health effects (see Chapter 6) than the main distribution system.

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Drinking Water Distribution Systems: Assessing and Reducing Risks Exposure through Vapor and Bioaerosols. Stripping and formation of bioaerosols in relatively confined spaces such as home showers can be an important exposure pathway. This is relevant to waterborne disease caused by Mycobacterium avium and Legionella, as well as to overall exposure to volatile contaminants such as THMs and inhalation exposure to endotoxin (e.g., Little, 1992; Anderson et al., 2002; Mayo, 2004). Proximity to Service Lines. As discussed in Chapter 1, service lines carry water from the distribution main to the premise plumbing in the building or property being served such that service line contamination can be a source of degraded water quality in premise plumbing. The majority of water leaks in a distribution system occur in service lines, service fittings, and connections (ferrules, corporation stops, valves, and meters) (AWWA, 2005). These locations therefore provide the greatest number of potential entry points for intrusion. The lower total chlorine residuals, lack of dilution, and short detention time before potential consumption might increase the potential health threat to individual consumers if intrusion were to occur at service lines. Little is known about the factors that might cause intrusion into service lines. Negative pressure transients could be responsible, but lower pressures and high velocities in service lines can cause a venturi effect (e.g., suction) and negative pressure waves due to water hammer that might also be significant. Compared to the main distribution system, much less is known about the type and cause of service line failures. Possibilities include internal and external corrosion, poor installation such as improper backfilling techniques and materials, damage during handling, and improper tapping. In general, the collection of data documenting the occurrence of such failures is poor. There is wide variation across the United States regarding ownership of service lines, which ultimately affects who takes responsibility for their maintenance. This can greatly complicate the extent to which service lines are inspected, replaced, and repaired in a timely manner when leaking. In most cases a drinking water utility, and thus most regulatory bodies, only takes responsibility for the quality of water delivered to the corporation stop, curb stop, or water meter. For that portion of the service line owned by consumers, the responsibility and cost of repairs fall on consumers, and the speed and effectiveness of repairs can therefore be even less efficient (AWWA, 2005). Prevalence of Cross Connections. In contrast to the main transmission system, it is relatively common for untrained and unlicensed individuals to do repair work in premise plumbing. Furthermore, as discussed in Chapter 2, there is tremendous variability in state cross-connection control programs, both with respect to the breadth of the programs and the extent to which these programs are routinely enforced at the local level. As a result of these factors, premise plumbing is more likely to have cross-connections and potential backflow events than the main transmission system. For example, repairs by consumers as simple as replacing a ballcock anti-siphon valve in the toilet tank can create a direct

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Drinking Water Distribution Systems: Assessing and Reducing Risks cross connection if the line to the tank is not air-gapped. Hazardous chemicals added to the tank could then backsiphon or backflow under some circumstances. In a study in Davenport, Iowa, 9.6 percent of homes were found to have direct cross connections to a health hazard, most frequently due to failure to air gap the line in the toilet tank. Only 4.3 percent of homes investigated did not have a direct or indirect connection to a health hazard (USC, 2002). It should be noted that for individual residences, backsiphonage is the greatest risk. However, it does not occur frequently, and when it does it would likely only affect a small population (usually only the population utilizing the building). Thus, these events are likely to be underreported. Backflow events are more likely to be reported when they occur in institutional settings, potentially affect a larger population, and are more likely to propagate back into the main distribution system. The EPA white paper on cross connections (EPA, 2002a) makes it clear that the majority of backflow events occur in premise plumbing. As shown in Table 8-2, the portion of the distribution system controlled by the utility accounted for only 18 of 459 reported backflow events. Responsible Party. There is lack of clarity over who is responsible for maintaining water quality in premise plumbing. Many consumers mistakenly believe that EPA regulations and their water utility guarantee that tap water is always safe to drink. Some public advertisements and educational materials reinforce the perception that EPA regulations and utility responsibility extend to the tap. Historically, however, in the United States the property line demarcating the public from the private system has not been crossed for regulatory purposes. The notable exception is the LCR, which has successfully reduced the general corrosivity of public water supplies in relation to lead and copper leaching. But ultimately individual homeowners and building supervisors bear final responsibility for protecting themselves from excessive lead or copper exposure and other degradation to water quality occurring beyond the property line. Economic Considerations. The net present replacement value of premise plumbing and the corresponding cost of corrosion far exceed those for the main distribution system (Ryder, 1980; Edwards, 2004). Moreover, costs associated with premise plumbing failures are unpredictable and fall directly on the consumer. Leaks occurring in premises also have implications for insurance renewal and mold growth. Leaching and Permeation. Leaching and permeation mechanisms are the same in premise plumbing as in the main distribution system. However, the higher pipe surface area to water volume ratio, very long stagnation times, and lessened potential for dilution increase the potential severity of the problem in premise plumbing. If permeation were to occur through a consumer’s service

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Drinking Water Distribution Systems: Assessing and Reducing Risks TABLE 8-2 Numbers of Documented Backflow Incidents from 1970 to 2001. Location of cross connection Number of reported backflow events Homes 55 Apartments 27 Mobile homes 1 Neighborhoods 3 Public Water Supply 15 Medical buildings 27 Schools 31 Other government buildings 24 Restaurants 28 Office buildings 18 Other commercial buildings 66 Agricultural, recreational, and industrial sites 56 Unknown or other miscellaneous sites 108 SOURCE: Adapted from EPA (2002a). line or premise plumbing, it would not be detected by routine distribution system monitoring. Scaling/Energy. At present about eight percent of U.S. energy demand is attributable to costs of pumping, treating, and heating water, and water heating accounts for 19 percent of home energy use (EPA, 2005). Hot water systems and small diameter tubes in premises are more sensitive to build up of scale, which can increase head loss and decrease water heater efficiency. The implications and costs of scaling in buildings tend to constrain the range of feasible water chemistries that might be considered to protect public health. For example, higher pH values that might be desirable to reduce nitrification and protect public infrastructure from internal corrosion could cause unacceptable scaling. GAPS IN RESEARCH AND MONITORING The preceding section highlights some of the unique challenges posed by premise plumbing relative to the main water distribution system. Even more so than with the main distribution system (see Chapter 3), very few studies have been done to assess the magnitude of the public health threat posed by premise plumbing. This is partly due to a lack of water quality monitoring in premise plumbing. Normal distribution system monitoring under EPA regulations often utilizes taps located in buildings, but water is thoroughly flushed from the pipes before sampling with the exception of samples for lead and copper. Thus, if there were problems related to water quality in a given premise plumbing system it would not necessarily be detected. No drinking water maximum contaminant levels (MCLs) protect consumers against water quality degradation resulting from premise plumbing.

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Drinking Water Distribution Systems: Assessing and Reducing Risks While solid evidence is not available, water quality degradation occurring within premise plumbing may have public health implications. For instance, recent trends in the United States to decrease water heater temperature to minimize scalding and save energy could be increasing the growth of opportunistic pathogens. Increased use of phosphate inhibitors, chloramine disinfectants, and point-of-use devices can also benefit or worsen the ultimate quality of water after it is held stagnant in premise plumbing. However, the lack of monitoring and isolated nature of problems that are discovered hinder rigorous risk analysis. Considering the emergence of Legionella and Mycobacterium as waterborne pathogens, and recognizing the threat from these microbes arising from regrowth in premise plumbing systems, more decisive action is necessary. For instance, existing EPA regulations are likely to produce water with a low level of Legionella in water leaving the treatment plant, but the effective Legionella levels in premises may still result in adverse health effects. There are 8,000–18,000 estimated Legionella cases in the United States each year with a fatality rate between 10 and 15 percent (http://www.cdc.gov/ncidod/dbmd/diseaseinfo/legionellosis_t.htm). Drinking water was judged responsible for 12 percent of Legionella cases in one case study mentioned in the United Kingdom (VROM, 2005a), but the methodology and certainty of that analysis is open to question. If a similar percentage of Legionella cases in the United States were caused by drinking water in premise plumbing systems, the health threat from Legionella alone would be very high relative to all other reasonably quantified risks from waterborne disease. Despite this relatively well established and high health risk, only a few studies have been conducted into possible broad community interventions that might reduce risk in buildings. Those studies have consistently found that chloramine was more effective than free chlorine in reducing Legionella levels (Kool et al., 1999a,b; Pryor et al., 2004; Stevens et al., 2004). A recent study in San Francisco demonstrated that the change from free chlorine to chloramine reduce the percentage of buildings with detectable Legionella from 60 percent to 4 percent, respectively (Flannery et al., 2006). However, one of the studies found higher levels of mycobacteria after chloramination (Pryor et al., 2004), and the possible impact of free ammonia as a nutrient on Legionella growth (if chloramine were to completely decay) has not yet been assessed. Nor have studies correlated Legionella occurrence and concentrations in drinking water with actual outbreaks of legionellosis. Targeted research to improve understanding of water quality degradation within premise plumbing is recommended and must overcome several challenges. All three approaches discussed in Chapter 3 for relating distribution system contamination events to public health risk (pathogen occurrence measurements, outbreak surveillance, and epidemiology studies) have unique challenges that increase the difficulty of their execution when applied to premises. Legionella has only recently (since 2001) been added to the CDC outbreak surveillance system. Unfortunately, existing CDC outbreak data would rarely implicate premise plumbing because backflow and regrowth events likely would

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Drinking Water Distribution Systems: Assessing and Reducing Risks not be reported unless an institutional building with large numbers of people was affected. Furthermore, there are minimal data on exposure routes other than ingestion, and this is yet another reason why so few data exist on the health effects of Legionella in tap water. The CDC has recently changed it reporting requirements for the outbreak surveillance system so that outbreaks that arise from events in premise plumbing are more clearly identified (see Chapter 3). Box 8-1 presents one of the few outbreaks clearly linked to contamination of premise plumbing. The little epidemiological research done to date has attempted to track the impacts of premise plumbing components on gastrointestinal upset (e.g., Payment et al., 1997; Colford et al., 2005), but not health problems arising from exposure to bio-aerosols as would be necessary for Legionella and Mycobacteria. The Davenport study (LeChevallier et al., 2003, 2004; Colford et al., 2005) BOX 8-1 Waterborne Disease Outbreak Associated with Premise Plumbing Contamination: North Dakota, USA, April 1987 Ethylene glycol is a solvent with a sweet, acrid taste that is used in antifreeze solution and in heating and cooling systems in buildings. Ingestion of ethylene glycol causes acute poisoning with central nervous system depression, vomiting, hypotension, respiratory failure, coma, convulsions, and renal damage, depending on the dose. The fatal dose for adults is approximately 100 g. Several incidents of ethylene glycol ingestion have been reported to the CDC waterborne disease surveillance system. All these incidents have involved public buildings and have been linked to contamination of premise plumbing through backflow via cross-connection with an air conditioning or heating system. In April 1987, two children in rural North Dakota were admitted to a local hospital with acute onset of somnolence, vomiting, and ataxia. Toxicologic analysis of their urine indicated the presence of ethylene glycol. Further investigation revealed that both children had been to a picnic earlier in the day at a fire hall in rural North Dakota. Approximately 400 persons had attended the picnic, and telephone interviews with about 91 percent of the attendees identified 29 additional cases of apparent ethylene glycol poisoning with 66 percent of the cases occurring in children under ten years of age. The most frequently reported symptoms were excessive fatigue and sleepiness, unsteadiness when walking, and dizziness. Data collected during the telephone interview about food and beverages consumed during the picnic indicated that one beverage, a noncarbonated soft drink, was strongly associated with illness (relative risk = 31.0). A clear dose-response was also observed among children, with no cases occurring among children who did not drink the implicated beverage, two cases among children who drank less than or equal to half a cup, five cases among children who drank one-half to one and a half cups and 12 cases among those who drank more than one and a half cups. The implicated beverage had been prepared on-site using a powder mix and water drawn from a spigot near the fire hall heating system that used a mixture of water and antifreeze and was cross-connected to the potable water supply. There was a valve on the cross-connection but no information on whether the valve had been closed before collecting water to prepare the beverage. Other foods and beverages had been prepared in the fire hall kitchen, and the kitchen sink was about 30 feet from the spigot with the cross-connection. A water sample collected from the spigot on the evening of the picnic was determined to have an ethylene glycol concentration of 9 percent. SOURCE: MMWR September 18, 1987/36(36):611-4.

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Drinking Water Distribution Systems: Assessing and Reducing Risks is the only known example of an epidemiology study where premise plumbing was investigated as a source of contamination contributing to gastrointestinal upset, and no impact was observed. Payment et al. (1997) cited a lower incidence of gastrointestinal upset after water contacted premise plumbing, and speculated it was due to disinfecting properties of copper. Of course very high levels of soluble copper in water leached from premise plumbing can also cause gastrointestinal upset (Craun et al., 2001). Thus, a range of health impacts from premise plumbing issues can be expected. With respect to pathogen occurrence measurements in premise plumbing, there is also no regulation or even voluntary standards recommending such sampling, and as a result background data are not being collected. Guidelines from the CDC (CDC, 2003, 2004) exist for Legionella in high risk buildings such as hospitals where an infection control officer is often responsible for monitoring and mitigating risk, but such monitoring and control measures are not routinely followed in other situations or in individual residences. Indeed, the current EPA guidelines on scalding prevention run counter to common control measures for Legionella (see section below under Policy Alternatives). Other opportunistic pathogens such as Mycobacteria are emerging concerns, for which there is a weaker link to disease and therefore even less incentive for monitoring. Monitoring samples could be collected by utilities from public buildings or from consumers’ homes during Lead and Copper Rule monitoring. Box 8-2 discusses the routine monitoring conducted on tap water in Seoul, South Korea. WHY HOME TREATMENT DEVICES ARE NOT ALWAYS THE ANSWER Home treatment devices have become increasingly popular as a means to further treat drinking water supplied by public water systems, and they are considered to be a potential technical solution to some problems associated with premise plumbing. There are a myriad of available devices designed to remove organic and inorganic chemicals, radionuclides, and microbiological agents from tap water. Common home treatment devices include point-of-use (POU) devices that are mounted at the end of the faucet, canister type devices that are plumbed in-line under the sink, stand-alone pitchers in which water is gravity fed through a filter, and refrigerated filtered-water systems. Home treatment devices used to treat the entire flow into the premise are called point-of-entry (POE) devices. POE devices can be as simple as a water softener to more complicated devices that combine sediment filters, activated carbon filters, and ultraviolet (UV) disinfection. Home treatment devices can range in cost from tens of dollars for a pitcher-type filter to thousands of dollars for a whole house treatment system. Most devices have components that need to be changed at a regular interval or after a specified volume of water has been treated. Membranes for reverse osmosis treatment systems are changed at a given frequency or when there is a reduction

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Drinking Water Distribution Systems: Assessing and Reducing Risks were less favorable. However, specific localities could choose to require retrofits. The American Society of Plumbing Engineers has recommended a similar approach in the United States (George, 2001), but the official recommendation from EPA is that consumers reduce their water heater temperature to 48° C to save energy, prevent scalding, and reduce scaling (EPA, 2004). Many U.S. water utilities highlight the EPA advice to reduce water heater temperatures on their web page. Problems Addressed By Regulation: Control of Regrowth in Premise Plumbing Systems Consistent with the current U.S. approach, English water companies have met their obligations if a failure to meet standards at the tap can be attributed to degradation occurring in privately owned premise plumbing (Colburne, 2004; Jackson, 2004; WHO, 2005). But in public buildings, including schools, hospitals, and restaurants, water quality must meet all regulations for potable water at the tap. While details are still under discussion, guidelines suggest that water must be sampled at taps in 10 percent of public buildings each year. “First draw” samples for bacteria must also be collected, and disinfection of sample taps is not allowed before collecting samples (Colburne, 2004). A similar regulatory approach could be considered of U.S. utilities to detect microbially unstable water and rapid disinfectant loss in premise plumbing. Legislation and regulation has also targeted operators of premise plumbing systems. In the Netherlands, the owners of collective water systems including hotels, camp sites, and sports facilities have been required to complete a risk analysis for microbial regrowth. The focus was mostly on Legionella, but a new Drinking Water Directive 98/83/EC also will eventually consider other microbial parameters at the tap (Regal et al., 2003). If a high risk is identified, the owner must indicate measures to protect against Legionella (VROM, 2005a,b). A recent survey of European approaches to controlling Legionella found that some countries directly addressed premise plumbing issues (VROM, 2005b). Problems Addressed By Voluntary Compliance: Hong Kong A survey in 1999 that revealed 48 percent of Hong Kong respondents rated their water quality at the tap fair to poor, but also indicated that less than 0.1 percent of the customers made complaints to the water company. Beginning in 2001 the Advisory Committee on the Quality of Water Supplies (ACQWS) began meeting to discuss strategies that would protect water to the tap. The key concerns were turbidity and discolored water from older galvanized plumbing. Various strategies were initially considered including:

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Drinking Water Distribution Systems: Assessing and Reducing Risks encourage designers of new buildings to design plumbing with water quality at the tap in mind educate the public to increase confidence and encourage drinking of water from taps and to maintain plumbing systems encourage renovation of plumbing systems as part of routine maintenance inspection programs for older buildings to determine if they need maintenance, with potential issuance of orders requiring repair require building owners to inspect internal plumbing using licensed plumbers and submit a report, with possible fines for non-compliance empower utilities to make repairs or remediation for consumers when problems are persistent A staged plan was considered for implementing some of the above strategies, in which the first three years of effort would focus on education of consumers, required implementation at government or quasi-governmental buildings, and voluntary compliance. Thereafter, if progress was unsatisfactory, laws would be considered. Loans were already available to customers from the building department for maintenance of plumbing. Consideration eventually gave rise to a Fresh Water Plumbing Quality Maintenance Recognition Scheme in buildings. The general idea is to create market forces that would make compliance desirable for participants. Voluntary successful applicants are awarded a certificate that can be used as a symbol of effective premise plumbing maintenance to the consumers’ taps. To qualify, the plumbing system must (1) be inspected at least once every three months by qualified personnel, (2) have all defects quickly repaired, (3) have water tanks cleaned every three months, and (4) have water samples collected at least once a year for analysis. The program is overseen by the water supply department, and the program is confidential. Checklists are provided for tank cleaning and water quality analysis and inspection. The program was started in July 2002; 32 months later, 2,807 certificates had been issued for residential buildings, hotels, and restaurants. Logos are provided to place on taps, and the time period in which certified compliance is valid is indicated. About 34 percent of residential households were covered by the program. Other progress included issuance of a plumbing maintenance guide, which might eventually become mandatory. A system was in development to track problem premises for which frequent complaints occurred. A survey was conducted of approaches for controlling premise plumbing problems in other Asian cities, and the results are included in Table 8-3. In general, the survey revealed that consumers in many of the Asian cities do not drink water from the tap (< 0.5 percent drink tap water directly in Hong Kong).

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Drinking Water Distribution Systems: Assessing and Reducing Risks Problems Addressed by Public Education Because water utilities have very limited control beyond the water meter of the customer, much of our existing information on water quality is not relevant to premises. Thus, there is a need to engage customers in identifying problems and coming up with solutions through public education. A multifaceted and long-term approach to providing safe drinking water from the treatment plant to the water meter is already used by the drinking water industry—one that involves compliance with the Safe Drinking Water Act, use TABLE 8-3 World-wide Perspectives on Responsible Party to Prevent Degradation of Water Within Premise Plumbing. Country Approach U.S.A. Explicit requirements for Lead and Copper only. Utility has responsibility to “Optimize” corrosion control to minimize Pb/Cu at the tap of select homes. Regulated by “action levels” for lead and copper. Lead pipe and solder banned in new construction. Guidelines for lead in schools but no regulation. U.K. By-laws in some instances requires draw off point for potable water directly from utility services, thereby completely avoiding home plumbing and allowing direct access to drinking water. Compliance with all regulations required at the tap in public buildings. Hong Kong Utility publishes free books and TV ads to encourage upgrades to plumbing and to clean storage tanks. Inspection for dirt and testing for bacteria (utility inspects based on complaints). Singapore Code of practice for consumers and their agents recommends that samples from various premise plumbing locations be examined periodically by water analysis. Chemical examination is beneficial in showing if corrosion is taking place, and bacterial contamination can be determined by sampling. Storage should be inspected at least once a year and cleaned. For “housing estates” and government buildings the recommendations are followed, but for “private estates” recommendations are voluntary. Reports are made to the water department. Making the recommendations into law was being considered. Shenzen, China At least every half year, water tanks must be cleaned and sterilized, with testing of water quality at the inlet and outlet by labs. The water company has responsibility for this task for low-rise buildings whereas the building owner has responsibility in high rises. The building management bears the cost, and a financial penalty can be given to those not complying. Reports are required to the water utility and department of health. Taipei, Kuala Lumpur, Malaysia Consumer generally has complete responsibility. However, Kuala Lumpur requires sufficient residual chlorine, and the desirability of regularly cleaning cisterns is publicized in newspapers and on television in Taipei. SOURCE: Adapted from ACQWS (2005), except the entry for the United States.

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Drinking Water Distribution Systems: Assessing and Reducing Risks of AWWA and ANSI standards for specifications and best practices, and enrollment in certification programs such as the Partnership for Safe Water and AWWA’s QualServe. This broad approach involves regulations, best practices, and peer review. However, regulation might prove to be the most expensive way and least efficient way to reduce risk and achieve control when one considers the customers’ premises as an integral component of the distribution system. Rather, regulation is only part of an overall approach to minimizing the risk from everyday use of tap water. Public education is needed to spur the public to incorporate new actions into everyday life. Similar changes are needed within the water and plumbing industries, such as the sanitary handling and storage of materials that come in contact with drinking water. Concepts such as the value of water, the need to conserve water (which has already taken place in some areas of the United States), and the need for good materials in guaranteeing good water quality are basic to bringing about solutions to problems the drinking water industry is faced with. These concepts must become part of the public psyche, as natural as washing ones hands after handling raw meat. Altering public behavior with respect to water will requires a multifaceted approach, broad-based support, and long-term commitment. It will require numerous efforts directed at premise plumbing such as: Basic education of concepts in elementary schools and higher education Education of trades such as plumbing contractors and building supervisors in health effects of premise plumbing, and the need for standards in products and design Available, easy-to-understand information in public libraries Government officials, politicians, consumers, and advocacy groups who are properly educated and can represent the best interests of the public at large Health officials, doctors, and nurses who educate their patients and the public on how to minimize risks in practical and achievable ways. Some progress has been made in the above areas for control of Legionella in institutional settings through published voluntary guidelines (ASHRAE, 2000; CDC, 2003). For the analogous problem of indoor air pollution and radon control, EPA has developed “A Guide to Indoor Air Quality” (EPA, 1995) that is easy to understand and which highlights the nature of the health threat and mitigation strategies that can be implemented to reduce the magnitude of the risk. A similar manual with an accompanying website would be highly desirable relative to premise plumbing systems. At a minimum the manual should include consideration of: Taste, odor, and aesthetic issues that can arise from premise plumbing Maintenance, including flushing of water heaters

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Drinking Water Distribution Systems: Assessing and Reducing Risks Issues related to energy conservation, scalding, and microbial regrowth in water heaters Trade-offs with different types of water heaters Benefits, limitations, and appropriate uses for various POU and POE devices The need to prevent cross connections Risks of untrained repair Recognizing obvious repairs or plumbing designs that could be problematic Troubleshooting premise plumbing problems, with information on who to contact for additional information, investigation, and repair. CONCLUSIONS AND RECOMMENDATIONS Premise plumbing should be recognized as a contributor to the loss of distribution system integrity, particularly due to microbial regrowth, backflow events, and contaminant intrusion via holes in service lines. Improper design or operation of premise plumbing systems can pose a substantial health threat to consumers, although additional research is needed to better understand its magnitude. In particular, more extensive sampling of water quality within premise plumbing by utilities or targeted sampling via research is required. The following detailed conclusions and recommendations are made. Communities should squarely address the problem of Legionella, both via changes to the plumbing code and new technologies. Changes in the plumbing code such as those considered in Canada and Australia that involve mandated mixing valves would seem logical as a compromise that would prevent both scalding and microbial regrowth in premise plumbing water systems. On-demand water heating systems may have benefits worthy of consideration versus traditional large hot water storage tanks in the United States. It may be desirable for building owners to conduct risk analysis for Legionella on their properties as per the Netherlands, and to develop a plan to address obvious deficiencies. The possible effects of chloramination and other treatments on Legionella control should be quantified to a higher degree of certainty. To better assess cross connections in the premise plumbing of privately owned buildings, inspections for cross connections and other code violations at the time of property sale could be required. Such inspection of privately owned plumbing for obvious defects could be conducted during inspection upon sale of buildings, thereby alerting future occupants to existing hazards and highlighting the need for repair. These rules, if adopted by individual states, might also provide incentives to consumers and building owners to follow code and have repairs conducted by qualified personnel, because disclosure of substandard repair could affect subsequent transfer of the property.

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Drinking Water Distribution Systems: Assessing and Reducing Risks EPA should create a homeowner’s guide and website that highlights the nature of the health threat associated with premise plumbing and mitigation strategies that can be implemented to reduce the magnitude of the risk. As part of this guide, it should be made clear that water quality is regulated only to the property line, and beyond that point responsibility falls mainly on consumers. Whether problems in service lines are considered to be the homeowner’s responsibility or the water utility’s varies from system to system. Research projects are needed that specifically address potential problems arising from premise plumbing. Because no organized party has had clear responsibility for this problem, research has been under-funded. Three lines of research are needed, each of which would help to improve future understanding of the public health risks from distribution systems: Collection of data quantifying water quality degradation in representative premise plumbing systems in geographically diverse regions and climates. Some of the needed data include those routinely collected in the main distribution system, including water residence time, disinfectant residuals, and microbial monitoring. In addition, greater attention should be focused on understanding the role of plumbing materials. Furthermore, the role of nutrients in distributed water in controlling regrowth should be assessed for premises because their longer holding times, chronic lower disinfection residuals, warmer temperatures, and most importantly their colonization by opportunistic pathogens such as Legionella and Mycobacterium avium make the biological stability of the water even more important than in the main distribution system. Specialized sampling is needed to quantify regrowth of opportunistic pathogens such as Legionella and Mycobacteria as a function of consumer water use patterns, plumbing system layout, and water heater operation. Finally, the potential impacts of representative POU and POE devices need to be quantified. Practical insights should be developed regarding exposure routes other than ingestion, including inhalation of bioaerosols from water. Effects of climate, consumer behavior in bathing and showering, and the specifics of plumbing system design and operation are likely to be key contributing factors in disease transmission from premise plumbing contamination. With respect to contracting disease such as legionellosis, such information would make it possible to develop steps that might reduce risk or explain why disease is contracted in some cases and not in others. An epidemiological study to assess the health risks of contaminated premise plumbing should be undertaken in high risk communities. Without information from the two bullets above, it would be very difficult to identify such groups with confidence.

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Drinking Water Distribution Systems: Assessing and Reducing Risks Environmental assessments of outbreaks should begin to incorporate new insights and allow possible cause-and-effect relationships to be established. Such assessments have traditionally focused on documenting outcomes of waterborne disease and not on key factors related to human exposure. Chapter 3 has documented that the reporting of outbreaks is being revised to include more explicit consideration of distribution system and premise plumbing deficiencies that might contribute to waterborne disease. Much greater emphasis must also be placed on dose reconciliation in outbreaks, which would require specialized sampling techniques for bioaerosols in the case of premise plumbing, in order to develop basic practical data on dose-response relationships. It is possible to genetically link bioaerosols to microorganisms that infect humans (e.g., Angenent et al., 2005); this type of analysis must be attempted with greater frequency to establish cause-and-effect relationships in potable water. REFERENCES Advisory Committee on the Quality of Water Supplies (ACQWS). 2005. Papers # 7, #8, #9, #13, #15 and Minutes of Meeting April 22, 2004. Available on-line at http://www.wsd.gov.hk/acqws/eng/home.htm. Accessed May 10, 2006. Angenent L. T., S. T. Kelley, A. Amand, N. R. Pace, and M. T. Hernandez. 2005. Molecular identification of potential pathogens in water and air of a hospital therapy pool. Proceedings of the National Academy of Sciences 102(13):4860–4865. Armstrong (Armstrong International, Inc.). 2003. Controlling Legionella in domestic water systems. 2003. Available on-line at http://www.bbriefings.com/pdf/13/Hosp031_t_Armstron.pdf. Accessed August 10, 2005 American Water Works Association (AWWA). 2003. Nitrification. Available on-line at http://www.epa.gov/safewater/tcr/pdf/nitrification.pdf. Accessed May 10, 2006. AWWA. 2005. Are Service Lines the “Achilles Heel” of Your Distribution System? Webcast August 24, 2005. ASHRAE. 2000. Minimizing the Risk of Legionellosis Associated with Building Water Systems. Standard 12-2000. ISSN 1041-2336. Available on-line at: http://www.lakoshvac.com/enewsimages/guide12.pdf. Accessed May 10, 2006. Anderson, W. B., R. M. Slawson and C. L. Mayfield. 2002. A review of drinking-water-associated endotoxin, including potential routes of human exposure. Can. J. Microbiology 48:567–587. Brazos, B. J., J. T. O’Conner, and S. Abcouwer. 1985. Kinetics of chlorine depletion and microbial growth in household plumbing systems. Pp. 239–274 (Paper 4B-3) In: Proceedings of the American Water Works Association Water Quality Technology Conference. Houston, Texas. Brongers, M. P. H. 2002. Appendix K of drinking water and sewer systems in corrosion costs and preventative strategies in the United States. Report FHWA-RD-01-156. Washington, DC: U.S. Department of Transportation Federal Highway Administration. Calderon, R. L., and E. W. Mood. 1987. Bacteria colonizing point-of-use, granular activated carbon filters and their relationship to human health. EPA CR-811904-01-0. Washington, DC: EPA.

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