AbstractForum papers are thought-provoking opinion pieces or essays founded in fact, sometimes containing speculation, on a civil engineering topic of general interest and relevance to the readership of the journal. The views expressed in this Forum article do not necessarily reflect the views of ASCE or the Editorial Board of the journal.IntroductionThe COVID-19 pandemic has affected public drinking water systems in unprecedented ways due to protracted disruptions in supply chains, customer demand patterns, staffing, and revenue (Berglund et al. 2021; Sowby 2020; AWWA 2020a). Water systems qualify as “critical infrastructure” according to ASCE’s and others’ definitions (ASCE 2021), and as such, they must keep operating not just despite, but especially during, times of crisis.Major disasters often trigger a strong response in research, policy, and practice (like the US Bioterrorism Act that followed the terrorist attacks on September 11, 2001), but pandemics present special kinds of problems (Sowby 2020). Although research on most hazards is abundant, pandemics differ in their frequency, duration, acuteness, geographic reach, and depth and breadth of impact. The 1918–1919 Spanish flu was the last worldwide pandemic, and sanitation, infrastructure, and population have changed in the century since then. Outbreaks of other diseases have occurred more recently but have been limited to local or regional scales. Indeed, a global pandemic has not beleaguered modern infrastructure and society until now. The problem is that many critical services, like drinking water, are built on principles of stability and predictability (Allenby et al. 2020) that COVID-19 and other recent happenings like wildfires and droughts have now upended. It is a wake-up call to transform civil infrastructure to better handle complexity and uncertainty.Now well over a year and a half into the coronavirus pandemic, the situation calls for a better grasp of how drinking water systems and other civil infrastructure have been affected, how they will continue recovering, and what they can do better in the future. Berglund et al. (2021) raised the similar questions for water and wastewater resource systems in general; here, we focus on drinking water. Some of the lessons learned may apply not just to pandemics but to complex, large-scale disruptions in general.As such work takes shape, we raise the following four key issues: 1.The need to capture unique research opportunities.2.The need to consider 1–3-year time scales in resilience research.3.The need for research cocreated by industry and academia to advance solutions.4.Questions to stimulate research.Each is discussed in the following sections.Unique Research OpportunitiesAs unwelcome as it may be, the backdrop of a global pandemic provides fertile ground for studying how sociotechnical systems react to a prolonged, cross-cutting disruption. The long-awaited opportunity to calibrate and validate systems models with empirical observations has finally arrived. It is an enormous experiment, a unique window of opportunity to study how water systems adapt over time and how this fresh understanding can be incorporated into new planning strategies, design standards, and operational approaches.The pandemic has opened two specific areas of concern that can now more definitively be studied. One is the possibility of an indirect cascading disturbance coming from an interconnected system to impact a water system. There have been studies of the impacts of natural hazards (Grigg 2003; Quitana et al. 2020), power failures (Adachi and Ellingwood 2008; Healey et al. 2021), and economic downturns (Mann and Runge 2010; Qi and Chang 2011) on water systems, but those all had direct connection to physical and institutional components of the water system. In the case of COVID-19, the direct connection is to the consumers. This provides a chance to study the cumulative, cascading effects of a disruption lasting months or years.The second unique research opportunity is the study of compound hazards. Water systems and other infrastructure may still remain in a disturbed state from COVID-19, and it is now possible to observe how they are affected by other short- and long-term disturbances that punctuate it. Since the pandemic began, the US has seen hurricanes in the Gulf Coast, winter storms and power outages in Texas, and record wildfires and crushing droughts in the west. A notable disruption of global significance was the weeklong obstruction of the Suez Canal in 2021. The superposition of such hazards on a pandemic is rare and lends itself to many unique and valuable studies.Time Scales of 1–3 YearsThe initial response to COVID-19 is over, and the world is now entering the long recovery phase where infrastructure systems adjust to a new normal. Much effort was expended early in the pandemic to inform rapid responses, but less attention has focused on the longer-term effects over 1–3 years. This time period is where pandemics again differ from other hazards and deserve particular attention to aid future planning.Most resilience research appears to address disturbances with durations of seconds to weeks (e.g., earthquakes and floods) or decades (e.g., climate change), but pandemics fall somewhere in between. Cutter et al. (2008) argued that the temporal scale is important because it dictates the measurement and strategies for resilience. But a review by Meerow et al. (2016) concluded that most measures of resilience to a disturbance either (1) emphasize “rapid” recovery, but set no firm deadlines, or (2) emphasize returning to a predisturbance level, regardless of the time scale.Like Chelleri et al. (2015), we advocate for considering the time scales in between short-term and long-term responses. Certainly, the disturbance of COVID-19 on the functionality of infrastructure is somewhere in between: the effects are being felt many months after the pandemic started, and will likely continue for 1–3 years, with some effects lasting even longer due to permanent shifts in user behavior, supply chains, system operations, and economies. For comparison, the Spanish flu lasted about 26 months in 1918 and 1919, so this time frame is reasonable based just on the disease propagation, which is the only recent pandemic data point we have. Indeed, the COVID-19 pandemic has dragged on much longer than even experts initially imagined; as of this writing, cases are again rising sharply in the US, some 18 months after the virus first arrived, underscoring the need to continue studying the problem and adapting our infrastructure approaches.This 1–3-year perspective is a gap in current research. As our infrastructure systems continue to become more interdependent at the same time that hazards become more profound and populations become more connected, multiyear effects of individual disturbances are much more likely. As such, the 1–3-year time scale deserves more attention from researchers who can help practitioners understand and mitigate the impacts.Research Cocreated by Industry and AcademiaAlthough some research results are beginning to be published, and many studies are ongoing at the time of this writing, the impacts of COVID-19 on drinking water systems will certainly be the subject of much more study, with implications for planning, modeling, design, construction, operation, permitting, monitoring, and compliance. A critical need now is catalyzing, stimulating, and funding the research to benefit from the unique opportunities and critical needs that have surfaced in the wake of COVID-19.As these research activities continue, we, like others (Gude and Muire 2021; Sowby and Walski 2021), urge researchers to collaborate with drinking water system staff, regulators, consultants, and vendors to cocreate work that benefits multiple stakeholders. Research in the area of hazards and resilience is not lacking, but its application in practice is. Few water practitioners seem to be aware of what research has occurred and how it could help them, and researchers may be missing opportunities to amplify the impact of their work by collaborating with industry partners. When studying water systems in the context of a phenomenon as pervasive as COVID-19, balanced perspectives from academia and industry are crucial.Academia must strengthen the conduit connecting academic research with technology development and water practitioners. Academics must bring their holistic systems view to broaden water utility research to include interconnected systems. A key foundation for the advances in research is preparing students to enter the workforce and support the evolution of water systems to meet post-COVID-19 challenges. Another important step is to think of water systems (and the analytics emerging from their digitalization) as research platforms to study a wider range of sociotechnical questions.Research QuestionsTo facilitate research on how COVID-19 has affected and will continue to affect drinking water systems, we outline here some broad questions, loosely organized by themes of demand, infrastructure, water quality, cybersecurity, staffing, supply chains, economy, preparedness, and policy. Table 1 presents the themes and overarching questions, on which we elaborate subsequently. Some questions arise from the authors’ experience with various US water utilities, from conversations with water professionals listed in the “Acknowledgments,” or from anecdotes reported to date; other questions are purely speculative. Although these are focused on drinking water, the same kind of multidisciplinary research is encouraged in all infrastructure systems.Table 1. Research questions for studying COVID-19 impacts on drinking water systemsTable 1. Research questions for studying COVID-19 impacts on drinking water systemsThemeOverarching questionDemandHow and why have the timing, magnitude, and location of water demands changed because of COVID-19?InfrastructureHow do new differences between design and operation affect water facilities?Water qualityHow have new demands and operations affected water quality?CybersecurityWhat are the cybersecurity implications of more remote operation and automation of water facilities?StaffingTo what extent has water system staff capacity been affected?Supply chainsHow have water systems’ supply chains been affected and what can be done to strengthen them?EconomyHow can water systems handle the financial instability associated with COVID-19 and other disasters?PreparednessAre drinking water systems prepared to handle another pandemic?PolicyWhat are the policy implications of COVID-19 for the water industry?Demand: How and Why Have the Timing, Magnitude, and Location of Water Demands Changed because of COVID-19?Sociotechnical systems and their interdependencies became apparent as the pandemic unfolded. COVID-19 has disrupted normal water use patterns along with normal ways of life. As a result of so much stay-at-home activity in 2020, water systems have observed shifts in water use from urban centers to suburbs, from residential to commercial buildings, and from early morning to midmorning (Berglund et al. 2021; Li et al. 2021; Lüdtke et al. 2021; Aquatech 2020; Balacco et al. 2020; Goldberg and Quail 2020; Raftelis 2020; Spearing et al. 2020). Such changes in both the diurnal curves and the spatial distribution may have consequences for pressure, water age, leakage, revenue, and overall performance. Possible research questions include the following: •How will performance of water distribution systems respond to spatial and temporal demand changes from modifications to work commutes, school attendance, and tourism?•What effect do spatial and temporal demand alterations have on water loss, water age, and water quality?•How permanent and significant are changes in development trends and consumer behavior after COVID-19, and what do they mean for planning scenarios?•What are the management implications of modified demand patterns in terms of staff, revenue, and breakage patterns?•What role can advanced metering infrastructure (AMI) and automation play to help existing systems to adapt to sudden and/or permanent fluctuations to demand?Infrastructure: How Do New Differences between Design and Operation Affect Water Facilities?Historically, the design of infrastructure systems has assumed that future conditions will be similar to past conditions (Allenby et al. 2020). However, COVID-19 has forced water systems to confront entirely different scenarios than those they were designed for, including possibly permanent demand shifts. This gap between design and operation deserves attention, including its severity and its consequences for water system performance. Further, although advances in asset management, rehabilitation, smart metering, automation, demand forecasting, artificial intelligence, and customer engagement were all gaining momentum before the pandemic, water systems must now evolve in these directions while also considering COVID-19. Possible research questions are as follows: •How did COVID-19 change the operation of water systems relative to the past, and how serious are the changes?•What changes in water infrastructure and operations are needed to fortify systems with resilience to multiyear disruptions?•Are water source portfolios diverse enough to handle short- and long-term disruptions of individual sources?•How can the current digital revolution of water systems be aligned with identified needs related to short-term and long-term infrastructure adaptations (Poch et al. 2020)?•What are the implications of COVID-19 for aging infrastructure and replacement priorities?Water Quality: How Have New Demands and Operations Affected Water Quality?The work-from-home evolution accelerated by COVID-19 may have a long-lasting impact on water demand patterns that will likely affect water quality in the distribution system well beyond the point of treatment. For example, reduced water demand and longer water residence times in school, commercial, and hospitality buildings may result in elevated lead or copper levels or increased bacteria counts (e.g., Legionella) (Berglund et al. 2021; Deem 2020; AWWA 2020b). Water systems should evaluate options for flushing or circulating water, maintaining disinfectant residuals, and bringing in chlorinated water to an otherwise low-flow area. Some research questions to consider are as follows: •Are some pipes and water tanks now oversized (such as those serving commercial areas where demand has decreased), consequently increasing water age, increasing disinfection by-products, and reducing disinfectant residuals in the distribution system?•Have new demands changed flow direction or velocity in ways that affect water quality, such as dislodging protective layers, causing new mixing effects, or changing the pH and redox potential conditions in the distribution system?•Have chemical availability or other supply chain factors adversely affected water treatment processes?•Has water quality monitoring continued through the pandemic, and are water systems still compliant? If not, what are the health and regulatory consequences?•What water quality impacts occur when water service resumes in buildings where premise plumbing has been inactive for weeks or months?Cybersecurity: What Are the Cybersecurity Implications of More Remote Operation and Automation of Water Facilities?While still maintaining essential onsite staff, many water utilities have relied more on Supervisory Control and Data Acquisition (SCADA) systems, accessed via the Internet, to operate their water facilities. Although cybersecurity has long been an issue in the water industry (Germano 2019; West Yoast Associates 2019), the pandemic-related decentralization and automation of water operations prompts some important questions: •How prepared were water systems for the security requirements of a sudden shift to remote operations?•Has more remote operation exposed water systems to new cyberthreats?•Do water systems have enough control and capacity to operate remotely for long periods of time?•What is the appropriate balance of onsite and remote operation?•How can water systems enhance their cybersecurity to allow the necessity of remote operation?Staffing: To What Extent Has Water System Staff Capacity Been Affected?Where many businesses simply shut down or went remote during the worst parts of the pandemic, water utilities have not had the same options. Some physical presence is still necessary, but with pandemic precautions, and water utility staff have had to learn a new way of working (Berglund et al. 2021; Gude and Muire 2021). Specific questions include the following: •How have personnel infections affected staff capacity? (This one is admittedly difficult to gauge because of medical privacy.)•How have water systems handled staffing issues, like maintaining social distancing, working remotely, operating with staggered shifts, sequestering essential staff, and/or operating with fewer people (AWWA 2020a)?•What pandemic-related workplace modifications for water systems are practical and effective?•Have staff been adequately protected while working onsite (e.g., social distancing and face masks)?•Have enough water operators been available during the pandemic? Are shared or backup operators available? Are operation procedures and manuals available, updated, and sufficiently detailed for outside operators to run the facilities without prior training?Supply Chains: How Have Water Systems’ Supply Chains Been Affected and What Can Be Done to Strengthen Them?As COVID-19 disrupted supply chains worldwide, some of those impacts extended to drinking water systems. Supply of personal protective equipment (PPE), for example, was a common challenge (Spearing et al. 2020), along with chemicals for water treatment and fittings and equipment for pipes. Even as late as July 2021, chlorine supplies were unstable, causing water treatment plants to change disinfection methods and/or coagulants (i.e., ferric chloride to ferric sulfate) to compensate.Research may consider these questions: •Have water systems been able to get enough treatment chemicals, identify alternative treatment chemicals, parts, equipment, and tools (AWWA 2020a)? If not, what are the consequences and how are they dealing with it?•Should water systems stock more of these supplies for emergencies? What are the associated costs, shelf life, and practices?•What are the consequences of a lack of personal protective equipment for water system operators?•How long can water systems continue to operate without utility services like power, gas, and Internet?•What are best practices regarding alternative suppliers, consecutive connections with neighboring water systems, mutual aid partnerships, and backup systems?Economy: How Can Water Systems Handle the Financial Instability Associated with COVID-19 and Other Disasters?According to AWWA (2020a), 32% of water utilities have struggled to maintain revenue as a result of the pandemic. Another survey likewise found that delinquent accounts and revenue decreases were common (Spearing et al. 2020). Loss of commercial sales, where water rates are often higher, is a particular challenge. Revenue from water sales as well as funding from external sources, like state and federal revolving funds, may be affected for years to come—all while water service must continue. Research questions might address the following: •How can water systems mitigate the lost revenue due to customers’ inability to pay their water bills or from lower commercial water sales? (Raftelis 2020)•Do water systems have sufficient cash reserves and business continuity plans? (Moyer et al. 2013; AWWA 2018, 2020a)•What financial resources can water systems quickly access in a crisis (Brodmerkel et al. 2020), and how can they position themselves to secure funding from the American Rescue Plan Act (ARPA) and future emergency funding?•How will COVID-19 affect water pricing and payment strategies?•How can water utilities overcome a loss of government funding and/or tax revenue associated with the pandemic?Preparedness: Are Drinking Water Systems Prepared to Handle Another Pandemic?According to AWWA (2020a), 61% of water utilities did not have a pandemic plan in place, even though they have long been encouraged to do so. Although it is too late to prepare for COVID-19, lessons may still be learned. The majority of water utilities say they are already documenting lessons learned (AWWA 2020a; States 2020). Further work is needed to review these lessons and develop best practices for the future. Some questions to consider include the following: •Do emergency preparedness plans address pandemic scenarios and other multifaceted hazards specifically?•What about pandemics makes them more difficult for water utilities to prepare for than other emergencies?•How can these pandemic-specific challenges be overcome?•How are water systems incorporating lessons learned from COVID-19 into their emergency planning, such as the risk resilience assessments (RRAs) and emergency response plans (ERPs) required by America’s Water Infrastructure Act (Sowby 2020; AWWA 2020a)?•How can these lessons be collected, synthesized, and shared? What best practices do they suggest?Policy: What Are the Policy Implications of COVID-19 for the Water Industry?New policies around preparedness, regulation, resilience, and communication will no doubt follow COVID-19 to prepare the water industry for future incidents. Research to inform these policies could address the following questions: •How effectively do existing policies help water utilities prepare for and respond to emergencies (Sowby 2020)?•What should be the roles of federal, state, and local governments in such policies? What should be the role of professional associations? (Consider ASCE’s policy statements on emergency water supply, emergency preparedness, resilient infrastructure, critical infrastructure definitions, and resilience research.)•What are best practices for risk communication and interaction with customers and regulators (AWWA 2019; Oerther and Watson 2020)?•How should resilience and emergency response regulations, like those in America’s Water Infrastructure Act, be revised in light of COVID-19?•How many states have allowed regulatory discretion (enforcement versus relief) on drinking water systems in response to COVID-19 mitigations? What are the consequences for public health?ConclusionThe COVID-19 pandemic, although unfortunate, presents a unique opportunity to study infrastructure. As a rare and wide-reaching disruption, the pandemic has affected drinking water and other infrastructure systems in observable ways. We can use this chance to validate models and further investigate how interdependent infrastructure has adapted and will continue to adapt, even as the recovery period is punctuated by other disasters like wildfires and hurricanes. Such research should explore a 1–3-year time frame likely to capture the effects of pandemics, which differ from other short-term hazards like earthquakes and long-term hazards like climate change. Because COVID-19 is both a prelude to coming challenges and a call to prepare for them, these studies should inspire new solutions, born of research cocreated by academia and industry, to guide how to design, build, and operate drinking water systems for the future and the complex hazards it may bring. To that end, we propose numerous research questions for students, researchers, practitioners, and funders to explore. The concepts and investigations are not limited to drinking water, and we encourage their extension to other critical infrastructure.Data Availability StatementNo data, models, or code were generated or used during the study.AcknowledgmentsEarly concepts for this paper benefited from the insights of Steve Burian (National Water Center, University of Alabama), Dave Judi (Pacific Northwest National Laboratory), Ying-Ying Macauley (Utah Division of Drinking Water), Tim McPherson (Pacific Northwest National Laboratory), Gary Miller (Western Municipal Water District), Alan Roberson (Association of State Drinking Water Officials), and three anonymous municipal water officials.References Adachi, T., and B. R. Ellingwood. 2008. “Serviceability of earthquake-damaged water systems: Effects of electrical power availability and power backup systems on system vulnerability.” Reliab. Eng. Syst. Saf. 93 (1): 78–88. https://doi.org/10.1016/j.ress.2006.10.014. 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