Threats to critical infrastructure are increasing, especially within the water industry. The purpose of this study was to evaluate the history of water attacks within the United States, determine the vulnerabilities, examine current and future methods of attack, and identify potential trends. Risk assessments of the water supply systems were evaluated based on threats, vulnerabilities, and consequences according to the 4 attack methods: physical, cyber, biological, and chemical. Each attack method was given a comprehensive background in the context of historical evidence, vulnerabilities, prevention, and response to a potential attack. In analyzing the risk assessment of water supply systems, it was determined that a majority of the vulnerabilities are due to outdated equipment or structure failure. Additionally, the increase in cyber-attacks worldwide signals a threat the U.S. is unprepared for. Therefore, physical, cyber, biological, and chemical attacks can be best mitigated through prevention and detection. Some prevention methods include establishing emergency protocols, training employees in risk management, and running emergency simulations.

The intent of this dissertation was to advance the knowledge of the impacts of building design and use on the quality of the potable water. Fluctuations in water use by occupants and equipment can cause stagnant conditions that causes water quality decay such as loss of chlorine disinfectant, an increase in microorganism and pathogen growth, an increase in metals concentrations, and an increase in disinfection byproducts. The United States Environmental Protection Agency has drinking water standards for distribution systems, but these standards stop at the meter with exception of the Lead and Copper Rule. There are also building codes to ensure proper plumbing materials are used that come in contact with potable water. However, neither standards nor codes require building water quality monitoring. Therefore, monitoring the building potable water system is an important aspect of building water quality that is not done on a large scale.Chapter 2 investigated how water quality evolved in a “green”, multi-story, institutional building during the first 6 months of building life. The results indicated that Wi-Fi logins could be used to correlate occupancy activity and copper (Cu) concentrations in water. As occupancy activity increased, Cu concentrations decreased. However, chlorine (Cl2) residual (or free chlorine) was only measurable twice at two kitchen sinks via grab sampling during the duration of the 6-month study regardless of occupancy activity. Chapter 3 provided improved understanding of how to carry out effective building water sampling (e.g., grab samples vs real time) and which water quality parameters were most influenced by the building water system during the first year of occupancy in relation to municipal water quality. The results showed the temperature (T), pH, UVA254, a surrogate for organic matter, cellular adenosine triphosphate (cATP), trihalomethanes (THMs), and Cu were always greater inside the building than at building entry while free Cl2 was always lower inside the building than at the building entry. Chapter 4 investigated a remedial flushing program for three schools. Overall, the study showed the quality of water does change after a flushing event. Free Cl2 was reestablished, and metals concentrations decreased. However, equipment flushing, such as hot water heaters, may be necessary to fully remediate Legionella. Lastly, one-time flushing is most likely a temporary solution. A more routine approach to building flushing and monitoring may be necessary until normal or sustained occupancy resumes.

Chlorine is a typical disinfectant that is used in water treatment. There are different forms and types of chlorine that are used as disinfectants, City of Tempe uses free chlorine. Regulations require that a residual is detected to ensure drinking water is “safe.” Large commercial buildings can undergo difficulties with maintaining a chlorine residual on every floor due to issues with underusage or lack of occupancy. Monitoring systems can activate an automatic flow of fresh water throughout the building or in a specific location based on set levels of chlorine within the monitoring system. There are different approaches to monitoring chlorine residual. Chlorine sensors are the typical process, but can be very expensive due to replacement materials required to promote further use of the sensor and acquire accurate measurements. Also, the chlorine system may require continual maintenance due to membrane replacement and management of the pressurized flow, which is required for accurate measurements. Oxidation reduction potential (ORP) is an efficient alternative from a cost perspective and accurate if the relationship between chlorine and ORP is understood.