In Brazil, the noise generated by plumbing systems into buildings is still little studied. Despite residents of multi-family vertical building citing this pathology as a cause of discomfort and complaints, there is not yet a standard that regulate noise measurements of hydrosanitary installations in the country in loco. This paper has as objective to establish an adequate measurement procedure of sound pressure level based in ISO 16032 (ISO, 2004) appropriate to evaluation the noise of plumbing systems, executed according to national standards, aiming to provide acoustic comfort to users. To verify the standard applicability, a 10 floor residential building, not inhabited yet, in the city of Santa Maria, with reinforced concrete structure and masonry wall, was chosen. The hydrosanitary devices measured were the faucet of the sink and the flushing cistern of the toilet bowl, both located in the master bathroom of the background apartments. The measurements was realized in suites, in 5 floors, and in the master bathroom of the 9th floor. The general rule was that the sanitary devices to be measured were triggered in the master bathroom, of the autonomous unit situated 1 floor above the suite, where was the microphone. However, exceptions occurred on the 10th and on the 7th floor, where measurements were made relating to hydrosanitary devices of the same floor and of two floors above, respectively. Therefore were measured and subsequently analyzed, all quantities allowed by ISO 16032 (ISO, 2004), in the weighting A and C, they are: Leq,nT, LFmax,nT and LSmax,nT. Were also performed measurements of the reverberation time of the suites according to ISO 3382-2 (ISO, 2008). After analyzing the results, it was found that in the situation of measurements, some results of the sink were influenced or masked by residual noise. Finally, to ensure the usefulness of the measurement procedure used, the results were compared with unique values expressed in NBR 15575-6 (ABNT, 2013) and was then evaluated the performance of hydrosanitary installations of the building, in situations that apply to standard. It is considered, therefore, that this paper contributed to the improvement of studies that search to enlarge the acoustic comfort in the Brazilian buildings, to establish measurement procedure of sound pressure level for the noise evaluation of plumbing systems. / No Brasil, o ruído gerado pelas instalações prediais hidrossanitárias ainda é pouco estudado. Apesar dessa patologia seguidamente ser citada como motivo de desconforto e reclamações, por parte de moradores de edificações residenciais multifamiliares verticais, ainda não há no país uma norma que regulamente medições de ruído de instalações hidrossanitárias in loco. Este trabalho teve como objetivo estabelecer um procedimento de medição dos níveis de pressão sonora, com base na ISO 16032 (ISO, 2004), apropriado para avaliação de ruído de instalações hidrossanitárias executadas conforme os padrões brasileiros, visando proporcionar conforto acústico aos usuários. Para a verificação da aplicabilidade da norma, foi escolhido um prédio residencial de 10 pavimentos, ainda não habitado, na cidade de Santa Maria, com estrutura de concreto armado e paredes de alvenaria. Os aparelhos hidrossanitários medidos foram a torneira do lavatório e a caixa de descarga da bacia sanitária, ambos localizados no banheiro da suíte dos apartamentos de fundo. As medições foram realizadas nas suítes em cinco diferentes pavimentos e no banheiro da suíte do 9º andar. Por norma, os aparelhos sanitários a serem medidos são acionados no banheiro da unidade autônoma situada um pavimento acima de onde se instala o microfone. Isso foi realizado e, além disso, no 10º e no 7º pavimento realizaram-se medições referentes aos aparelhos hidrossanitários do mesmo pavimento e de dois pavimentos acima, respectivamente. Foram medidas e, posteriormente analisadas, todas as grandezas recomendadas pela ISO 16032 (ISO, 2004), nas ponderações A e C, são elas: Leq,nT, LFmax,nT e LSmax,nT. Também foram realizadas medições do tempo de reverberação das suítes, segundo a ISO 3382-2 (ISO, 2008). Após a análise dos resultados, foi constatado que, na situação das medições, houve resultados do lavatório que foram influenciados ou mascarados pelo ruído residual. Por fim, para garantir a utilidade do procedimento de medição adotado, os resultados foram comparados com os valores únicos expressos na NBR 15575-6 (ABNT, 2013) e foi, então, avaliado o desempenho das instalações hidrossanitárias da edificação, nas situações que se aplicam à norma. Considera-se, portanto, que esse trabalho contribuiu para o avanço dos estudos que buscam ampliar o conforto acústico nas edificações brasileiras, ao estabelecer um procedimento de medição dos níveis de pressão sonora para avaliação do ruído de instalações hidrossanitárias.

Magma plumbing systems represent the physical framework of magma transport and storage from the source region in the mantle, through the crust, until reaching the surface in a volcanic eruption. Characterising the different aspects of magma plumbing, in particular the distribution of magma storage zones throughout the crust, is of key importance to better understand the behaviour of individual volcanoes. In particular, shallow crustal magma storage and associated magma-crust interaction processes could potentially explain some of the worlds most unpredictable and explosive volcanoes. This thesis studies magma plumbing architecture in the Sunda Arc (Indonesia), and the North Atlantic Igneous Province, based on elemental and isotope geochemistry, and derived petrological modelling. In this study, I have employed petrological models, so called geothermobarometers, to calculate pressures and temperatures (P-T) of crustal magma storage. Geothermobarometers are calibrated thermodynamic formulations based on the composition of magmatic minerals and their co-existing melt as a function of the P-T conditions of crystallisation. Using the calculated P-T estimates, I was able to derive the depth of magma storage, and thereby reconstruct the architecture of magma storage systems. A number of different geothermobarometers based on different mineral phases, including plagioclase, clinopyroxene and olivine, were used for this purpose, The geothermobarometric modelling was combined with additional elemental and isotope geochemical analyses, as well as collaborations with geophysical investigations. These additional approaches were used to corroborate the findings of the geothermobarometric modelling, and also to model and quantify magma-crust interaction processes that take place during crustal magma storage, such as assimilation of crustal lithologies into the magmatic system. The findings of this thesis build upon the growing body of evidence in support of the prevalence of shallow magma storage in different volcanic settings worldwide. This realisation is relevant to volcano monitoring and hazard mitigation worldwide.

No description available.

<p dir="ltr">The frequency and intensity of wildfires occurring at the wildland-urban interface is increasing, and public drinking water systems operating in these communities are at risk. Widespread volatile organic compound (VOC) and semi-VOC (SVOC) contaminations have been detected in water distribution systems, often at concentrations above regulatory limits. Uncertainty about the source and fate of these contaminants has hindered recovery efforts. It is hypothesized that one source of the contaminants is the thermal degradation of plastic components within water distribution systems. Plastics are commonly used for water conveyance due to their low cost and ease of installation. However, plastics are vulnerable to thermal degradation, and have been shown to release VOC/SVOCs into the air when thermally degraded. Further, certain plastics such as polyethylene, are vulnerable to organic compound permeation, which could result in the contamination of otherwise undamaged components. This dissertation is comprised of four studies aimed at evaluating if plastic components within water distribution systems may be a source of contamination post-wildfire.</p><p dir="ltr">First, the aqueous leaching from commercial drinking water pipes was evaluated following thermal degradation in air. In this work, eleven plastic drinking water pipes were exposed to elevated temperatures (200°C to 400°C), and subsequently submerged in water or in <i>n</i>-hexane to observe the extent of VOC leaching. Results indicated that thermally damaged drinking water pipes can be sources of VOC leaching, with ten of the eleven materials leaching benzene, a carcinogen, into water. As exposure temperature increased, there was an increase in VOC leaching from the polyethylene plastics. Conversely, in the vinyl plastics the significant mass loss associated with high exposure temperature was inversely proportional to the amount of leaching that was observed.</p><p dir="ltr">The second study determined how the direct contact of water during plastic thermal degradation impacts the formation and aqueous leaching. Experiments were carried out using a continuously stirred tank reactor (CSTR) to expose plastics to a range of temperature (100°C to 300°C) in the presence of water. Five polyethylene materials were tested, including three cross-linked polyethylene (PEX) pipes, one high-density polyethylene pipe (HDPE), and one HDPE resin. Following degradation, clean water was pumped through the reactor to evaluate the efficacy of flushing to remove contaminants from thermally damaged plastics. Again, material type and exposure temperature impacted the leaching profile. Flushing removed contaminants from the thermally damaged plastics, however the removal rate varied based on chemical properties. Exhumed materials from wildfire impacted water systems were extracted in water to assess similarities and leached up to twelve different compounds, seven of which were also detected in laboratory experiments.</p><p dir="ltr">The third study investigated the impact of polyethylene formulation on aqueous leaching following thermal degradation to further understand the underlaying phenomenon causing the formation and leaching of contaminants. The impact of resin density, antioxidant type (Irganox 1010^® or Irgafos 168^®), antioxidant dose (0 to 10 wt. %), and impact of carbon black (0 or 2 wt. %) was investigated by compounding 12 different composites and thermally degrading them in the CSTR reactor described previously. Results found that all variables tested impacted the observed leaching. The addition of antioxidants decreased the observed leaching of polyethylene degradation products but increased the leaching of a variety of antioxidant degradation products. Carbon black was found to interact with the antioxidants during compounding, leading their consumption, and as a result decreased their effectiveness in protecting the polymer chain.</p><p dir="ltr">Lastly, the susceptibility of plastic water supply connectors such as ice-maker lines, faucet connectors, and washing machines hoses was assessed. The vulnerability of rigid plastic materials within water systems has been well studied, however, water supply connectors tend to be made of flexible plastics such as plasticized PVC and low-density polyethylene, and limited data exists on the susceptibility of these materials to contamination. In this study, seven connectors were exposed to hydrocarbon contaminated water, and subsequently decontaminated by water flushing. Following an initial 24 h contamination period, water samples were collected at three consecutive periods of 72 h. Results found that all materials sorbed more than 90% hydrocarbon contaminants. All materials released contaminants into the water during decontamination, at times above health-based limits. The majority of sorbed mass remained in the plastics at the end of the decontamination periods.</p>

Residential water heating is linked to the primary source of waterborne disease outbreaks in the United States, and accounts for greater energy demand than the combined water/wastewater utility sector. To date, there has been little research that can guide decision-making with regards to water heater selection and operation to minimize energy costs and the likelihood of waterborne disease. We have outlined three types of systems that currently dominate the marketplace: 1) a standard hot water tank with no hot water recirculation (STAND), 2) a hot water tank with hot water recirculation (RECIRC), and 3) an on-demand tankless hot water system with no hot water recirculation (DEMAND). Not only did the standard system outperform the hot water recirculation system with respect to temperature profile during flushing, but STAND also operated with 32 – 36% more energy efficiency. Although RECIRC did in fact save some water at the tap, when factoring in the energy efficiency reductions and associated water demand, RECIRC actually consumed up to 7 gpd more and cost consumers more money. DEMAND operated with virtually 100% energy efficiency, but cannot be used in many circumstances dependent on scaling and incoming water temperature, and may require expensive upgrades to home electrical systems. RECIRC had greater volumes at risk for pathogen growth when set at the lower end of accepted temperature ranges, and lower volumes at risk when set at the higher end when compared to STAND. RECIRC also tended to have much lower levels of disinfectant residual (40 -850%), 4-6 times as much hydrogen, and 3-20 times more sediment compared to standard tanks without recirculation. DEMAND had very small volumes of water at risk and relatively high levels of disinfection. A comparison study of optimized RECIRC conditions was compared to the baseline modes of operation. Optimization increased energy efficiency 5.5 – 60%, could save consumers 5 – 140% and increased the disinfectant residual up to 560% higher disinfectant residual as compared to the baseline RECIRC system. STAND systems were still between 3 – 55% more energy efficient and could save consumers between $19 - $158 annual on water and electrical costs. Thus, in the context of “green” design, RECIRC systems provide a convenience to consumers in the form of nearly instant hot water, at a cost of higher capital, operating and overall energy costs. / Ph. D.

Worldwide water distribution infrastructure system is old and deteriorating. A water system with its myriad appurtenances (including pumps and valves and tanks) is susceptible to hydraulic transients resulting in high and low pressure waves alternatively passing through the network. While both low and high pressure events structurally tax the already weak system, there is copious evidence indicating intrusion of contaminants into the drinking water pipes from the pipe's exterior environment due to low pressure events associated with water hammer phenomenon. These contaminants enter into the drinking water as the home plumbing system is a passive recipient from the water main. While the major (municipal) system is readily recognized as a vast infrastructure system of nearly 1,409,800 km of piping within the United States, the minor (plumbing) system that is at least 5 to 10 times larger is generally not well analyzed. In this study, an experimental plumbing rig was designed and implemented that replicates the range of pressures encountered in actual minor water distribution systems. This research addresses how a pressure transient triggered within a house and from municipal systems can impact the service line with a possible suction effect. Experimental results on low pressure events and the accompanying numerical modeling showed good agreement. The experiment also enabled visualization of the various pressure transient phenomena. It is demonstrated that hydraulic transients triggered from water mains result in low pressures events (up to -10 psig) in service lines which can allow possible intrusion of microbial and chemical contaminants at the service line. Structural integrity of service line and hydraulic integrity at water mains should be maintained to minimize any public health risks. In the USA, about 90% of residential drinking water plumbing systems use copper pipes. Pinhole leaks in copper plumbing pipes have become a nationwide concern because these leaks cause property damage, lower property values, and result in possibility of adversely affecting homeowners' insurance coverage. In addition, resulting mold damage may cause health concerns. This research also addresses the concerns of the affected homeowners by enabling them to decide on whether to continue to repair or replace their plumbing system, the factors to be considered in a replacement decision, and the type of material to use for replacement. Plastic pipes such as PEX (cross-linked polyethylene), CPVC (Chlorinated Polyvinyl Chloride), and copper are considered in present analysis. Other alternatives include an epoxy coating technique on the existing piping systems, without the need to tear into walls. Multiple attributes of a plumbing system including cost (material plus labor charges), taste and odor impacts, potential for corrosion, longevity of the pipe system, fire retardance, convenience of installation or replacement, plumber or general contractor's opinions or expertise, and proven record in the market are considered. Attributes and material rankings are formalized within the framework of the preference elicitation tools namely AHP (Analytical Hierarchical Process). Surveys are conducted with selected homeowners in pinhole leak prone area in Southeastern US Community to observe their revealed and stated preferences. Participants' overall preference tradeoffs are reported in addition to comparing their revealed and stated preferences. Health effects, taste and odor of water turned out to be the most important factors from the survey. In real life, however, homeowners were not well aware of these safety issues related with plumbing materials. It is recommended that water professionals should work on bridging the gap between public perception and research results related to major and minor systems. / Ph. D.

An early phase continental rift is an emerging plate boundary where tectonic forces stretch and thin the continental lithosphere, shaping the Earth's surface. Continental breakup and its progression are typically driven by the interplay between repeated magmatic and tectonic activities, which have been explored through both tectonic and magma-assisted rifting models. Understanding volcano-tectonic interactions is key for evaluating the role of magmatic fluids in facilitating the initiation of continental breakup during early phase rifting. This study applies the magma-assisted rifting model to the Natron Rift and investigates volcano-tectonic interactions during early phases of continental breakup associated with observed changes in the volcanic plumbing system of the active volcano Ol Doinyo Lengai. The Natron Rift is a magma-rich rift in the southern segment of the Eastern Branch in northern Tanzania providing an ideal setting to explore the interactions between tectonic and magmatic processes in the early stages of rifting. To investigate tectonic and magmatic interactions, we began by characterizing the magmatic plumbing system of Ol Doinyo Lengai using Global Navigational Satellite System (GNSS) data from our TZVOLCANO network and Interferometric Synthetic Aperture Radar (InSAR) observations. We inverted the GNSS and InSAR data independently to identify potential deformation sources using the software dMODELS. We then conducted a joint inversion of both datasets and found results that were consistent with the independent inversions within 2-sigma uncertainty. Our findings suggest that Ol Doinyo Lengai is fed by an offset multi-tiered reservoir system, consisting of a shallow magma reservoir located east of the volcano connected to a deeper reservoir through a network of fractures. This magmatic system likely influences the nature, style, and magnitude of volcanic activity at the edifice. We also assessed temporal and spatial changes in surface motion observed with GNSS stations associated with magmatic activity to help mitigate risks to nearby communities, tourism, and air traffic. Detecting transient deformation is essential for forecasting eruptions since these signals often precede eruptive events. To detect transient signals using GNSS data from the TZVOLCANO network, we employed the Targeted Projection Operator (TPO) program which projects GNSS time-series data onto a target spatial pattern. We analyzed seven years of continuous GNSS data and divided the observations into three-year intervals. The TPO method detected rapid uplift between March 2022 and December 2022 followed by steady-state uplift through August 2023. The method also identified quiescent periods and non-eruptive inflation signals that enhance our understanding of the dynamic magma plumbing system of Ol Doinyo Lengai. When integrated with the TZVOLCANO network, which streams real-time GNSS data, this approach enables continuous monitoring and early detection of potential volcanic hazards. Ongoing monitoring is crucial for assessing volcanic risks and improving emergency response plans. Finally, we examined the role of interactions between tectonic and magmatic processes in the Natron Rift during the early stages of continental breakup, focusing on the evolution of the magma plumbing system beneath Ol Doinyo Lengai. Using the code PyLith, we developed a 3D model of the region. The modeling experiments test both homogeneous and heterogeneous medium, with and without topography to estimate surface deformation and stress changes on the Natron fault due to geodetically constrained magma source inflation and deflation. Our analysis focused on stress transfer from the magma sources to assess the likelihood of fault slip, considering the typical 0.1 MPa threshold for triggering slip in magmatic rift settings. Results indicate that during the inflation period from 2016 to 2023, slip on the Natron fault is inhibited adjacent to the volcano under all scenarios. During the magma source deflation phase that occurred from 2007 to 2008 due to explosive eruptions, slip on the Natron fault was promoted adjacent to the volcano under all scenarios. Shear stress change analyses reveal that during the magma deflation scenario, slip of the Natron fault is consistent with oblique normal fault movement that is dominated by normal faulting and has components of strike-slip motion. Finite numerical modeling results demonstrate that topography considerably influences stress changes caused by dynamic magma sources as compared to material heterogeneity highlighting the importance of incorporating topography in volcano-tectonic settings. This work suggests that the potential ongoing magmatic activity at Ol Doinyo Lengai and its proximity to the Natron Fault influence the development of the youthful Natron Rift during early phase rifting. However, this influence likely inhibits fault slip at present on the adjacent section of the Natron fault due to magma source inflation. / Doctor of Philosophy / Continental rifts in their early phases mark the initial stage of plate boundary formation, characterized by the stretching and thinning of the Earth's outer, rigid shell under tectonic forces. Rifts are a significant agent in shaping the Earth's rigid, outer shell, ultimately leading to the formation of oceanic basins and volcanoes. Rifting occurs when tectonic plates break apart, creating faults and allowing magma that formed deep in the Earth to rise to shallower depths. This process not only contributes to the geological evolution of our planet, but it also poses significant hazards in the form of earthquakes and volcanic eruptions. Understanding the interaction between tectonic activity, like slip on faults, and magmatic processes, like volcanic deformation, is essential for assessing rift behavior, particularly in the early, immature stages of rifting when volcanic and tectonic activities are closely linked. This research focuses on the Natron Rift, a magma-rich segment of the southern part of the Eastern Branch of the East African Rift System located in Northern Tanzania. This region includes the active volcano Ol Doinyo Lengai, which is known for its unique magma composition and a history of explosive eruptions. The Natron Rift is an ideal setting to study the interactions between volcanic and faulting processes since it is still in the early stages of rifting. We examined the volcanic structure beneath the active volcano Ol Doinyo Lengai and its surroundings to assess the sources of magma supplying the volcano. We analyzed the geometry and location of a magma source using Global Navigational Satellite System (GNSS) data from our TZVOLCANO monitoring network and satellite images. We used the software dMODELS to independently model the surface displacements and identify potential magma sources. We also combined both datasets and jointly modeled them to test the independent results, which suggested a shallow, deflating magma source located to the east of Ol Doinyo Lengai. The magma source we found is likely connected to a deeper one through fractures that feed Ol Doinyo Lengai. The magmatic system determined from this study influences the nature and intensity of volcanic activity. We further assessed how the surface of Ol Doinyo Lengai volcano changes over time in response to magmatic activity to better understand and reduce the risks posed by eruptions. Volcanic eruptions at Ol Doinyo Lengai pose a risk to nearby communities, tourism, and air traffic, making it crucial to detect surface changes that could indicate an impending eruption. We developed computer models that identified potential non-eruptive volcanic signals due to magma source changes using seven years of continuous GNSS data from our monitoring network. The detected transient signals include a period of rapid uplift from March 2022 to December 2022 followed by steady uplift through August 2023. When the difference between the observed data and the expected pattern three times larger, this difference indicates transient surface motion that could signal an eruption in the near future. This information provides valuable context for eruption forecasting and serves as an early-warning system for the surrounding communities. Continuous monitoring using real-time data from the GNSS network is essential for the early detection of volcanic hazards and improving emergency response efforts. Finally, we investigate the roles played by the interactions between tectonic and magmatic processes in developing the Natron Rift during early stages of continental breakup. We use advanced modeling software called PyLith to create a 3D model of the region that incorporates known magma sources and the Natron fault. We estimate the surface motions and stress changes on the Natron fault due to changes in the known magma sources (inflation or deflation). Our stress transfer analysis indicates that during magma source inflation from 2016 to 2023 the Natron fault near the volcano section is clamped and prevents fault slip. For the deflating magma source associated with 2007-2008 explosive eruptions, stress changes on the Natron fault adjacent to the volcano section indicated fault slip likely occurred with dominantly normal faulting that includes a small component of strike-slip motion. The incorporation of topography significantly affects the amount of stress transferred on the fault under all scenarios. This study suggests that current magmatic activity at Ol Doinyo Lengai along with its closeness to the Natron Fault affects how the early stage Natron Rift develops. However, this influence likely prevents fault slip currently on the volcanic section of the Natron fault because of magma source inflation inhibiting slip the fault.

Opportunistic pathogens (OPs) can naturally colonize premise (i.e., building) plumbing and are the leading cause of disease associated with potable water in the U.S. and many other countries. While secondary disinfectant is added by utilities prior to water distribution through pipes, the residual in water at the property line is sometimes insufficient to suppress OP growth. Conditions encountered in premise plumbing can further diminish disinfectant in water after it crosses the property line. This dissertation examines how multiple factors at play in drinking water distribution systems and premise plumbing influence OP growth in order to inform development of rational guidance to reduce incidence of waterborne illness. Operating an at-scale cross-linked polyethylene (PEX) plumbing system with one water flush per day, influent chloramine always decayed within four hours in stagnant pipes containing mature biofilms, which is 2-3 orders of magnitude faster than in the same water not contacting pipes. Chloramine often followed second order decay kinetics, though decay rate coefficients were highly variable with some taps eventually transitioning from second to first order decay over time or with increasing influent chloramine concentration. The rate of chloramine decay was unexpectedly reduced in the water heater tank compared to room temperature pipes, possibly due to lower surface-area-to-volume ratio and higher temperature within the tank. A complementary glass jar experiment confirmed that, contrary to expectations, chloramine could decay slower at the higher temperature of 37-39°C maintained in the water heater, compared to the cooler 19-30°C typical of the pipes. These findings demonstrate the need for disinfectant decay models specific to conditions encountered in premise plumbing. Nitrification, a key microbial process that can catalyze chloramine decay, was typically complete within 24 hours after water entered the stagnant pipes. Counterintuitively, the water heater had a relatively lower rate of nitrification along with some detectable denitrification. This work also showed that oxygen, essential for aerobic microbial growth, can permeate through walls of PEX pipe and enter into the water from the atmosphere of the building. Considering the unique array of conditions that were found to influence the persistence of disinfectants in premise plumbing, a new approach was proposed for managing OP risk, referred to herein as the "CT framework." CT was defined as the integral of the chlorine concentration (C) at a point in the premise plumbing versus water retention time (T). Legionella pneumophila was not detectable in pipes with a CT > 78 mg*min/L over a 24 hour period, which is comparable to reported CT thresholds for 3-log inactivation of biofilm-associated L. pneumophila in batch experiments. There was a tradeoff between control of L. pneumophila and Mycobacterium avium in the water heater, as M. avium increased by >1 log as influent chloramine and CT increased, while L. pneumophila decreased by >1.5 logs. Further research is needed to elucidate the influence of factors such as water storage tank hydrodynamics and sediment on the persistence of different OPs. Building water retention time was also found to be an overarching variable that governs microbial growth in some circumstances in premise plumbing. Total cell counts and L. pneumophila occurrence mirrored expected trends based on the classic microbial growth curve with phases of lag, exponential growth, stationary growth, and decay. The location in the plumbing system where each phase dominated depended on water retention time, disinfectant level, and temperature. The microbial growth curve considerations add an additional dimension to the CT framework for predicting L. pneumophila growth potential in premise plumbing. Specifically, elevated heat or chloramine, was able to temporarily suppress or even eliminate growth, but the phases of classic microbial growth could be restarted once disinfectant or very high temperatures were absent. Total cell counts and L. pneumophila typically peaked at a building water retention time of 7 days, demonstrating that once a week flushing guidance to protect public health may not be advantageous in all situations. Collectively, this work offers fundamental and practical insights into factors driving disinfectant decay and microbial proliferation in premise plumbing, offering a modified CT and microbial growth concept framework to help guide the management of OPs in premise plumbing. / Doctor of Philosophy / Access to safe drinking water is fundamental to human health and wellbeing and is considered to be a human right by some agencies. Opportunistic pathogens (OPs) can grow in some drinking water systems and cause deadly diseases, such as Legionnaires' Disease. Legionnaires' Disease and illnesses caused by other OPs are now the leading cause of drinking water-associated disease in the U.S. and many other countries. Chlorine or chloramine are disinfectants required to be present in treated drinking water in the U.S. before it is piped through the distribution systems to consumers. This helps to limit growth of OPs and other microbes in the distribution systems. However, the concentration of disinfectant that remains in water as it crosses the property line is sometimes inadequate to suppress OP growth. Even if the amount of disinfectant entering a building is boosted, there are some plumbing materials and circumstances that can quickly reduce the disinfectant. These challenges are sometimes worsened by water and energy conservation efforts, which extend the time water spends in a building and presents tradeoffs with preventing OP growth. This dissertation examines how multiple factors at play in drinking water distribution systems and building plumbing individually and collectively influence OP growth, with a goal of developing rational guidance to reduce incidence of waterborne illness. Experiments were conducted using a large at-scale building plumbing system. These experiments revealed new insights into the relationship among factors such as how long the water stagnates in pipes, water temperature, the disinfectant concentration at each tap, and the level of specific OPs of concern. Chloramine was gone within four hours of stagnation in plastic cross-linked polyethylene (PEX) pipes containing a mature biofilm, which is 100-1000× faster than observed in the same water that did not contact pipes. The rate at which chloramine disappeared changed with conditions from tap to tap, or with time at a given tap, in ways that were unexpected based on prior assumptions. Further, the hydraulic characteristics and low temperature of the water heater influenced chloramine decay in the tank in a way that increased survival and release of OPs. We found that other microbes residing in pipes, such as nitrifying microbes, can also play a role in decay of disinfectant and their activity also is controlled by the water retention time and temperature in the system. These findings reinforce the need to thoroughly understand how chemical, biological, and hydraulic factors combine to influence OP growth in buildings. To account for the array of factors that contribute to the decay of disinfectant, we introduce premise plumbing "CT" as a new integrative framework to guide management of OPs. We define CT as the integral of the disinfectant concentration (C) at a stagnant point in the building plumbing verses the time (T) water has resided at that point, to characterize the ability of the water to kill or suppress growth of bacteria. If the calculated CT values in the at-scale plumbing system were high enough, Legionella pneumophila, the OP that causes Legionnaires' Disease, was never detected in pipes. However, if CT was too low, L. pneumophila was not controlled. Oddly, M. avium, another problematic OP, exhibited a contradictory trend within the water heater. This indicates that the CT concept may not control M. avium in chloraminated water heaters with complex water flow patterns and sediment. Higher chloramine caused lower L. pneumophila and higher M. avium in the water heater, but this tradeoff did not occur in cold water pipes when the room temperature was below that required for OP growth, indicating that room temperature setpoint could be a significant factor for OP control in buildings. Building water retention time, which is the time that water takes to move through the plumbing before it is consumed from a tap, was identified in this research to be a key driver of microbial growth that can be readily controlled by building managers. Trends of total microbial cell count and L. pneumophila in the premise plumbing system and complementary experiments followed all the phases of growth associated with bacteria in a simple glass jar, including a lag, rise, peak, and then decay of cells. Elevated heat or chloramine was able to temporarily suppress growth or even kill cells, but the phases of growth were again observed once the chemical or thermal disinfectant was removed. In any building, there is likely a frequency of flushing water at a given tap that is "worst case" for bacterial growth. In the absence of disinfectant, bacteria in pipes that are frequently supplied with nutrients through fresh water can be expected to have sustained growth, but if bacteria are starved of nutrients, there is some die off. In our system, total microbial cell counts and L. pneumophila peaked at a water retention time of about one week. Thus, this work suggests that current advice to flush building pipes once a week might sometimes create issues with microbial growth rather than solve them. Collectively, this research advances both fundamental and practical understanding of the factors driving disinfectant decay and microbial proliferation in premise plumbing. The premise plumbing CT and microbial growth concept framework is introduced to help inform better management of building water systems to prevent or remediate the growth of pathogens and reduce risk of human infection.

Corrosion of drinking water distribution systems can cost water utilities and homeowners tens of billions of dollars each year in infrastructure damage, adversely impacting public health and causing water loss through leaks. Often, seemingly innocuous choices made by utilities, plumbers, and consumers can have a dramatic impacts on corrosion and pipeline longevity. This work demonstrated that brass pipe connectors used in partial lead service line replacements (PLSLR) can significantly influence galvanic corrosion between lead and copper pipes. Galvanic crevice corrosion was implicated in a fourfold increase in lead compared to a traditional direct connection, which was previously assumed to be a worst-case connection method. In field sampling conducted in two cities, a new sampling method designed to detect particulate lead risks demonstrated that the choice of flow rate has a substantial impact on lead-in-water hazards. On average, lead concentrations detected in water at high flow without stagnation were at least 3X-4X higher than in traditional regulatory samples with stagnation, demonstrating a new 'worst case' lead release scenario due to detachment of lead particulates. Although galvanized steel was previously considered a minor lead source, it can contain up to 2% lead on the surface, and elevated lead-in-water samples from several cities were traced to galvanized pipe, including the home of a child with elevated blood lead. Furthermore, if both galvanized and copper pipe are present, as occurs in large buildings, deposition corrosion is possible, leading to both increased lead exposure and pipe failures in as little as two years. Systematic laboratory studies of deposition corrosion identified key factors that increase or decrease its likelihood; soluble copper concentration and flow pattern were identified as controlling factors. Because of the high copper concentrations and continuous flow associated with mixed-metal hot water recirculating systems, these systems were identified as a worst-case scenario for galvanic corrosion. Deposition corrosion was also confirmed as a contributing mechanism to increased lead release, if copper pipe is placed before a lead pipe as occurs in partial service line replacements. Dump-and-fill tests confirmed copper solubility as a key factor in deposition corrosion impacts, and a detailed analysis of lead pipes from both laboratory studies and field tests was consistent with pure metallic copper deposits on the pipe surface, especially near the galvanic junction with copper. Finally, preliminary experiments were conducted to determine whether nanoparticles from novel water treatment techniques could have a negative impact on downstream drinking water pipeline infrastructure. Although increases in the corrosion of iron, copper, and stainless steel pipes in the presence of silver and carbon nanomaterials were generally small or non-existent, in one case the presence of silver nanoparticles increased iron release from stainless steel by more than 30X via a localized corrosion mechanism, with pitting rates as high as 1.2 mm/y, implying serious corrosion consequences are possible for stainless steel pipes if nanoparticles are present. / Ph. D.

Lead is a common additive in plumbing components despite its known adverse health effects. Recent research has attributed cases of elevated blood lead levels in children and even fetal death with the consumption of drinking water containing high levels of lead. Although the federal Environmental Protection Agency (USEPA) strives to minimize lead exposure from water utilities through the Lead and Copper Rule (LCR), an estimated 47 million U.S. residents reliant on private unregulated water systems (generally individual and rural) are not protected. Detection, evaluation, and mitigation of lead in private systems is challenging due to lack of monitoring data, appropriate sampling protocols, and entities to fund research. Through a statewide sampling survey, over 2,000 homeowners submitted water samples for analysis. This survey documented that 19% of households had lead concentrations in the first draw sample (i.e., 250 mL sample collected after 6+ hours of stagnation) above the EPA action level of 15, with concentrations as high as 24,740. Due to the high incidence observed, this research focused on identifying system and household characteristics that increased a homeowner's susceptibility of lead in water. However, 1% of households had elevated lead concentrations after flushing for five minutes, which highlighted potential sources of lead release beyond the faucet. Therefore, a follow-up study was conducted to investigate sources and locations of lead release throughout the entire plumbing network. Using profiling techniques (i.e., sequential and time series sampling), three patterns of waterborne lead release were identified: no elevated lead or lead elevated in the first draw of water only (Type I), erratic spikes of particulate lead mobilized from plumbing during periods of water use (Type II), and sustained detectable lead concentrations (>1 ) even with extensive flushing (Type III). Lastly, emphasis was given to understand potential lead leaching from NSF Standard 61 Section 9 certified lead-free plumbing components as the synthetic test water is not representative of water quality observed in private water systems. Overall, this dissertation research provides insight into a population that is outside the jurisdiction of many federal agencies. / Ph. D.