Abstract While basic access to clean water is critical, another important issue is the affordability of water access for people around the globe. Prior international work has highlighted that a large proportion of consumers could not afford water if priced at full cost recovery levels. Given growing concern about affordability issues due to rising water rates, and a comparative lack of work on affordability in the developed world, as compared to the developing world, more work is needed in developed countries to understand the extent of this issue in terms of the number of households and persons impacted. To address this need, this paper assesses potential affordability issues for households in the United States using the U.S. EPA’s 4.5% affordability criteria for combined water and wastewater services. Analytical results from this paper highlight high-risk and at-risk households for water poverty or unaffordable water services. Many of these households are clustered in pockets of water poverty within counties, which is a concern for individual utility providers servicing a large proportion of customers with a financial inability to pay for water services. Results also highlight that while water rates remain comparatively affordable for many U.S. households, this trend will not continue in the future. If water rates rise at projected amounts over the next five years, conservative projections estimate that the percentage of U.S. households who will find water bills unaffordable could triple from 11.9% to 35.6%. This is a concern due to the cascading economic impacts associated with widespread affordability issues; these issues mean that utility providers could have fewer customers over which to spread the large fixed costs of water service. Unaffordable water bills also impact customers for whom water services are affordable via higher water rates to recover the costs of services that go unpaid by lower income households.

Citation: Mack EA, Wrase S (2017) A Burgeoning Crisis? A Nationwide Assessment of the Geography of Water Affordability in the United States. PLoS ONE 12(1): e0169488. https://doi.org/10.1371/journal.pone.0169488 Editor: Jaymie Meliker, Stony Brook University, Graduate Program in Public Health, UNITED STATES Received: September 17, 2016; Accepted: December 16, 2016; Published: January 11, 2017 Copyright: © 2017 Mack, Wrase. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability: Information about water costs that is critical to reproducing study results is included as a Supporting Information file. The data used in the ANOVA analysis are from a publicly available data source, the National Historic Geographic Information System (NHGIS), and may be searched using the criteria provided in Table 3. Finally, a shapefile of high-risk at at-risk tracks has been uploaded to the One Water Solutions Institute at Colorado State University repository at the following URL: https://erams.com/waterconnect_resource/view/643c4d0c-bdd0-4a18-b399-12a9122b40ed. Funding: Funding for this research was provided by National Science Foundation (NSF) Sustainability Research Network grant 1444758 and NSF Supplement 1444758. Competing interests: The authors have declared that no competing interests exist.

Introduction While basic access to clean water is critical, another important issue is the affordability of water access for people around the globe. In terms of water affordability, studies have estimated that approximately 60% of the population in low-income countries could not afford water priced at full cost recovery rates[1]. This is problematic given that consumers do not pay the full cost of water because water is subsidized by the government in many countries or priced at below cost-recovery levels. While research has highlighted issues with access to affordable water in developing countries and some developed countries 2–4], more work is needed in developed countries to better understand the extent of this issue in terms of the number of households and persons impacted. In cities across the United States, water affordability is becoming an increasingly critical issue. Mass shutoffs in Detroit, Michigan have resulted in the termination of service for 50,000 households since the start of a campaign in 2014 to shut off water for delinquent residents[4]. In Philadelphia, Pennsylvania an estimated 227,000 customers, or 4 out of 10 water accounts, are past due [5]. Atlanta, Georgia and Seattle, Washington have some of the highest water rates in the country at $325.52 and $309.72 per month for a family of four, respectively [6]. These rates are based on 100 gallons (378.54 liters) of water per person per day including, water, sewer, and storm water for 5/8 inch (15.875 mm) meters [7]. It is likely these rates will rise as the cost of providing water increases. A variety of pressures ranging from climate change, to sanitation and water quality, to infrastructure upgrades, are placing increasing strain on water prices[8]. Estimates of the cost to replace aging infrastructure in the United States alone project over $1 trillion dollars are needed in the next 25 years to replace systems built circa World War II, which could triple the cost of household water bills [9]. Other studies estimate that adaptations to water systems to deal with climate change will cost the United States more than $36 billion by 2050 [10]. For example, an increasing number and intensity of weather events call for improvements to waste-water facilities to manage storm water [10]. A hidden pressure on urban water systems is slow or even declining population growth, which reduces the customer base over which the high fixed costs of water services are distributed, and places increasing pressure on household water bills. This is the case in Detroit where a declining population has left fewer customers to pay for water. Another critical issue is the suburbanization of people, which also leaves providers in core central city areas with fewer customers to pay for water services. This means that for cities across the United States, shrinking populations in particular metropolitan areas and in downtown areas, combined with other pressures on urban water systems, present a perilous future for water utilities and their customers [11]. Over the next few decades, water prices are anticipated to increase to four times current levels [8]. Prices could go higher if cities look to private providers for water services, who have a tendency to charge higher rates than public providers [12–15]. These pressures on water systems, combined with the fact that water is a vital necessity to sustain life, place this issue at the forefront of 21st century infrastructure challenges. While studies have found that Americans are willing to pay more to maintain and ensure access to water resources [8], this willingness to pay may conflict with their fundamental ability to pay for water. To date however, work on water affordability for low income households in developed countries has received somewhat less attention than work on water in the developing world [3]. International work on affordability [3,2,16,17] and case studies in the United States have highlighted specific communities where affordability is an issue [10,18]. While valuable, the extent that water affordability is a widespread issue for U.S. households, and where these households are located, remains unclear. This is vital to unravel since there is currently no federal statute or policy that ensures water access for poor residents [19]. Given this gap in work on water issues, the goal of this paper is to assess the extent that the ability to pay for water services is a potential issue for U.S. households. This assessment will create a benchmarking tool, based on EPA affordability standards, to provide a means of assessing the potential financial capacity of households to pay for water service. It will also assess the characteristics and geographic locations where residents are potentially susceptible to rising water rates. Results of this assessment highlight a possible affordability crisis in which an estimated 11.9% of households could find current water prices unaffordable; this percentage could triple to 35.6% if rates increase according to recent projections.

Assessing and Measuring Water Affordability Affordability is not only an issue for customers in the United States but for utility customers around the globe. This is the case for low-income households who must use a disproportionate share of income to pay for water services [3,2]. An affordability study in France highlights that single parent families, particularly female-headed households, and large households receiving social assistance are most at risk for affordability issues [20]. In many countries, water is also not priced at full cost recovery levels, which means that this affordability challenge is likely to worsen in the near future. For example, in several countries in Africa where the cost of infrastructure is subsidized by the state or donors, customers do not pay the full cost of water [1]. However, it is important to note that affordability issues are highly contextual and depend on the country analyzed, as well as the spatial scale of the analysis. A recent study of Tunisia found for example, that water rates were affordable and could sustain some form of price increase [21]. Water rates are also highly variable within countries and major metropolitan areas [22]. This means that affordability studies must be interpreted with some caution since results from one study area are likely not applicable to a range of consumers in other geographic locations and water provision contexts. Measuring Water Consumption Aside from the variability of water rates at a variety of spatial scales, the extent that water rates are deemed affordable depends on the water consumption level analyzed and the affordability benchmark used. In this regard, there is a wide range of consumption levels and benchmarks to consider. A variety of studies have highlighted that water consumption varies within and between countries [23,24], and that this variation is related to several characteristics of people and places ranging from climate lifestyle, diet, and income [25]. For example, Gleick [23] highlights that water use within the state of California alone varies between 42.17 gallons (171 liters) and 140.28 gallons (531 liters) per person per day. A more recent study highlights tremendous variation in water use within developed countries. Uruguay, for example, uses 16.11 gallons per person per day (61 liters per person per day (1/c/d)) while Canada uses 203.15 gallons per person per day (769 1/c/d) [24]. A good portion of these studies have attempted to unravel the minimum level of water consumption to meet human needs, with varied results. Gleick [23] suggests that the minimal level of water consumption is about 13.21 gallons (50 liters) per person per day. This is the equivalent of 396 gallons (1499.02 liters) per person per month. A more recent study estimates however that people need on average 35.66 gallons per person per day (135 1/c/d), which is over twice the recommended amount [23]. Determining basic water needs is challenging not only because of the unique climatic and cultural characteristics of place [25], but also because it is difficult to disentangle essential uses of water from non-essential uses [16]. In fact, there are several non-essential uses of water such as swimming pools, extra showers, and outdoor watering that raise average consumption levels across countries [16]. Perceptions of “essential” uses are likely to vary dramatically based on the income, culture, religion, and diet of people. A classic example of this is water use for personal hygiene. In several countries around the world, flushing toilets are a rarity while in other countries they are quite common, if not ubiquitous. Thus, the extent that flushing toilets are considered a hygienic necessity will influence the perception of baseline or essential uses of water. Measuring and Benchmarking Affordability Aside from variations in what is considered “essential” water consumption, affordability analyses are complicated by the variety of methods for quantifying affordability, and the variety of benchmarks used to assess affordability. That said, there are two basic approaches to quantifying affordability: expenditure based measures and income based measures [3]. Within these two categories, Hutton [26] highlights four affordability metrics: 1. Expenditures as a share of household income 2. Cost of equipment needed to access water 3. All water related expenditures as a percentage of household income and 4. Full financial and economic costs as a percentage of annual income. Each of these metrics has its advantages and disadvantages that stem from the ease of obtaining the data, to the comprehensiveness of the metrics. For example, expenditure data are generally easier to obtain, but do not necessarily cover the full cost of accessing and using water [26]. A consideration of the full financial and economic costs of water is more comprehensive, but is data intensive and involves the difficulties of measuring “true” economic costs [26]. In terms of expenditure-based compared to income-based measures, some studies suggest that expenditures provide a better sense of affordability because household income data do not include all sources of household revenue, particularly in developing countries with a large informal economy [3]. One of the primary issues with expenditure-based approaches is that households with average or above average incomes, who consume large amounts of water for non-essential purposes, may be deemed water poor [16]. This is quite a distinct situation from low-income households who might be classified as water poor, but whose water consumption is dedicated to essential uses of water only. Just as there are quite a few ways of measuring water affordability, so too are there a variety of benchmarks used to assess the relative affordability of water. Income-based benchmarks are more common than are expenditure-based benchmarks, which is demonstrated by the number of income-based affordability benchmarks used by several organizations. For example, the affordability standard adopted by the United Nations Development Program and the United Kingdom’s Department of the Environment, Transport, and the Regions (DETR) is 3% of household income. This benchmark is similar to the OECD recommendation that household water bills not consume more than 3–5% of household income [27,28]. The Unitary Universalist Service Committee advocates for 2.5% of monthly household income [10,26,29] which is similar to the U.S. Environmental Protection Agency (EPA) standard that households spend no more than 2% on water and 4.5% of median household income on both water and wastewater services [30]. The U.S. EPA threshold of 4.5% is similar to the World Bank income benchmark of 5% [1]. Although less popular than income-based benchmarks, an example of an expenditure-based affordability benchmark is 5% of household expenditures for water and wastewater services [3]. Given this range of affordability benchmarks, this study adopts the U.S. EPA’s income-based standard for measuring water affordability which states that combined water and wastewater services should comprise no more than 4.5% of median household income. This combined measure is used because water and wastewater services appear together on customer bills and because of the rising costs of wastewater treatment, which comprise a growing portion of water bills [6].

Pricing Water Providing water service involves a large amount of funds to deploy and maintain infrastructure. These funds are typically divided into two categories: 1. operations and 2. maintenance and capital improvements [31]. The second of these components covers the costs of new equipment, new facilities, infrastructure maintenance and rehabilitation costs to meet new regulatory requirements, such as those outlined in the Safe Drinking Water Act (SDWA), [31]. The goal in pricing water is to set rates that are low for consumers but also sufficient to recover the large fixed costs of building and maintaining infrastructure. A key facet of pricing water rests on the ability to achieve declining average costs. This means that the cost per consumer falls the greater the number of customers over which fixed costs can be distributed. If either the number of customers falls and/or the amount of fixed costs increases, water rates rise. Aside from the cost of providing service, another driver of water rates is the characteristics of the utility provider. In this regard, two characteristics, provider size and public or private orientation are important to consider. Large providers serve populations of 100,000 or more while small providers serve populations of 10,000 or fewer [32]. The size of provider is important to consider because recent research suggests that smaller providers face a variety of challenges including diminishing customer bases, fewer financial resources, and a lack of engagement in long-range planning [32]. In addition to provider size, the public or private orientation of providers also factors into water rates. In the United States, private entities can make a profit on water services while public providers are required to price water on a cost-recovery basis [12]. This means government-owned utilities are responsible for setting rates while investor-owned utilities set rates via water rate cases [33]. In both the government and investor-owned utility situations, the public plays a role in setting rates [33]. Private providers, however, set rates differently and are not mandated to restrict rates to cost recovery alone. Thus, several studies find that the rates of private entities exceed those of public providers [12–15]. While the majority of U.S. consumers are currently serviced by public providers [12], a growing proportion of water services in the U.S. may be provided by private providers in the near future, as U.S. cities grapple with a lack of funding for infrastructure. From this perspective, privatization offers the option to earn profits on water services, which may be used to fund other initiatives and balance city budgets [13]. From an affordability perspective, all of these pressures on water resources and infrastructure forebode rising water rates for consumers. However, the implications of these rate increases on the affordability of water services for U.S. households remain unassessed on a national scale. Instead, much of the work on affordability has emphasized the perspective of water providers [8,34–36],. Although this body of work acknowledges affordability issues for low-income households [8,34] more work is needed to assess who is impacted and where impacted households are located.

Discussion As water rates rise, and household incomes remain stagnant for the foreseeable future, the results of this nationwide assessment highlight a burgeoning affordability crisis for several states, and providers serving low-income households across the nation. The highrisk and at-risk households identified in this study face compounding economic factors that impact their ability to pay for water services. These factors include higher rates of unemployment, lack of health insurance coverage, and a reliance on foods stamps and public assistance. From a geographic perspective, populations most likely to suffer from rising water prices are concentrated in low-income states across the United States. They are also spatially clustered within metropolitan areas across the country, which is likely problematic for utilities who have high numbers of customers in these high-risk and at-risk groups. Thus, while water rates are currently unaffordable for an estimated 11.9% of households, the conservative estimates of rising rates used in this study highlight that this number could grow to 35.6% in the next five years. More dramatic rate increases could place an even larger segment of the population at-risk. The privatization of water services could also mean much higher water rates for customers. The privatization of water services is one of the factors behind the high water costs in Atlanta, Georgia, which at $325.52 per month has the most expensive water services in the nation [7]. For water to be affordable at these rates, households must make at least $86,805, which is 1.6 times higher than the most recent estimates of U.S. median household income of $53,657 [47]. That said, there are some limitations to this study that are important to note. First, water rates between providers are highly variable within metropolitan areas [22]. Thus, the sample of providers used to compute the average water rate in this study is not necessarily indicative of the water rates that all consumers pay. Second, incomes within census tracts are highly variable which means that the financial ability to pay for water services within metropolitan areas is also highly variable. Third, the study makes use of data from the American Community Survey (ACS), which is subject to a large degree of sampling error. This means that the median income figures used and the number of households that fall above and below this benchmark are variable and could change the percentage of high-risk and at-risk tracts estimated in this study. To determine the sensitivity of analytical results, robustness checks for the state level analysis in Tables 7 and 8 were run with data at higher levels of aggregation (i.e. the county). This analysis revealed that the states with a large number of high-risk and at-risk census tracts were robust to this change in the unit of analysis. Given the potential impact of rising water rates on a large segment of the population, solutions are needed to resolve this burgeoning affordability issue. Unfortunately, in the United States, assistance programs to help resolve affordability problems for consumers is left to the discretion of individual water providers [10]. A common approach for dealing with delinquent accounts is to shut off water services [5,48–51], and there is little households can do to combat this because there is no federal statute or policy that ensures water access for poor residents [19]. There are also no national standards to protect vulnerable populations (children, the elderly, disabled, and pregnant women) against the termination of water services due to default on payments, nor are there any federal laws or policies governing water affordability [10]. While affordability standards have been adopted by the United Nations and also the U.S EPA, the issue is that none of these standards have any legal framework regarding the enforcement of these standards. Given this lack of protection for vulnerable populations and other low-income consumers, it has been recommended that federal laws be put into place, similar to those in the United Kingdom, that make it illegal for service providers to disconnect water service due to nonpayment or delinquent payments [10]. In addition to the establishment of laws at the federal and/or state level, mechanisms for reducing the financial burden on households need to be put in place for low-income consumers. While there are a variety of strategies for reducing the financial burden on families, there are four basic types of assistance that could be devised. The first type of assistance would help all water consumers, and that is the financing of infrastructure outlays and improvements by the state and federal government. This approach would reduce the burden on individual providers and reduce the need for increased water rates, because it reduces one of the primary stressors on water rates, rising infrastructure costs. The second type of assistance would involve the subsidization of water services for qualifying low-income households by the local, state, and/or federal government directly. To do this, formal guidelines would need to be developed to determine who qualifies for assistance. Another means of subsidizing low-income households would be the use of community assistance programs to help households pay water bills. In this scenario, non-profit organizations collect and use donations to help households pay their bills [34]. A third type of strategy would involve a restructuring of water rates to reduce the financial burden on low-income consumers. This type of solution, and the best way to structure water rates, has received a lot of attention [17,34,52]. Recent research highlights that rate restructuring is a utility strategy for ensuring cost-recovery of the rising costs of water service [6]. Unfortunately, a rise in the fixed costs or minimum monthly bill for all customers enhances disproportionately the financial burden on low-income households who already face challenges with paying for service [7]. Raising consumer awareness about water use and water costs is a fourth strategy that could be implemented by utilities to help low-income households manage water use and budget for water costs [34]. This type of approach includes a range of options such as consumer counseling, increased frequency of water bills, and the promotion of water conservation strategies to reduce water use [34].

Conclusion As a variety of pressures on urban water systems from climate change, suburbanization, shrinking populations in deindustrialized cities, and rising costs of infrastructure grow, a range of actors (governments, utilities, and consumers) will need to work together to solve a growing affordability problem. Water is a fundamental right for all humans [53]. However, a growing number of people globally face daily barriers to accessing clean, affordable water. Thus, it is in the best interest of all people to work to resolve the rising costs of increasingly scarce water resources. This includes utilties who have a vested interest in solving the affordability riddle to mitigate the costs of unaffordable water that include water shut-offs, unpaid accounts, and the time and cost associated with debt collection efforts [8]. The goal of this study was to bring a geographic perspective to this topic in a United States context, which remains a comparatively understudied country in international work on water affordability issues. The hope of this piece is that enhanced awareness of this issue in the developed world will highlight the severity of this issue, which is not isolated to people in the developing world.

Acknowledgments Thank you to Theresa Conner from Colorado State’s One Water Solutions Institute and the anonymous reviewers who took the time to provide constructive feedback for this article.

Author Contributions Conceptualization: EM. Data curation: EM SW. Formal analysis: EM. Funding acquisition: EM. Investigation: EM SW. Methodology: EM. Project administration: EM. Resources: EM SW. Supervision: EM. Validation: EM SW. Visualization: EM SW. Writing – original draft: EM SW. Writing – review & editing: EM SW.