Residential Water Research Articles

Estimating Urban Green Space Irrigation for 286 Cities in China: Implications for Urban Land Use and Water Management

Urban green space has increased significantly in many cities in China as a result of rapid urbanization. Despite various environmental and societal benefits of urban green space, its irrigation water use has become an important yet under-researched issue in urban water management. Using a newly developed green space evapotranspiration and soil water budgeting model coded in Python, this research estimated the irrigation water requirement of urban green space for 286 cities at the prefecture level and above in China, with daily meteorological data in 1986–2011, the distribution and areas of urban green space from the 30 m resolution “Essential Urban Land-Use Categories in China” database, and green space types from the 10 m resolution “10 m resolution global land cover” database. The estimated annual average irrigation water requirement of urban green space for these 286 cities was 8.7 billion m3, accounting for over 20% of residential water consumption in the cities where data on residential water use were available. We also investigated the spatiotemporal variation of urban green space irrigation water requirement and the factors that influence such variations. To the best of our knowledge, this study develops the first set of results of urban green space irrigation for all major cities in China, thus providing useful insights for green space irrigation and urban water man-agement in the context of rapid urbanization and sustainable water management.

Reassessing the cost of hydropower for multi-function hydropower bases: A case study from Sichuan

Hydropower is an essential resource for the future clean energy transition, in which an accurate assessment of the hydropower cost is vital for promoting its share in the energy market. The purpose of this paper is to comprehensively reassess the cost of hydropower from a new perspective, in which the total static investment cost of a hydropower base is allocated among multiple functions. An allocation coefficient is proposed based on indicators of economic value and physical volume of multi-function hydropower bases. The economic value of each function is evaluated using approaches including the shadow project, market valuation, and emergy evaluation methods. Meanwhile, the physical volume is obtained through a multi-objective optimization of cascade reservoir operation considering an ecological constraint. Four main functions consisting of hydropower generation, flood control, agricultural irrigation, and residential water supply of hydropower bases in Sichuan are investigated. The results show that the allocation coefficients under both economic and physical indicators vary significantly among hydropower bases, and change slightly over the years. The average comprehensive allocation coefficient of hydropower is 57.26% (range from 29.83% to 77.41%), and the hydropower cost can be reduced by 59% from the current level. The reassessed hydropower cost can lay a solid foundation for market pricing. Attention should be paid to the multi-functionality characteristics of hydropower bases to achieve fair sharing of cost and benefit.

Exergy-economic assessment of a hybrid power, cooling and heating generation system based on SOFC

In this research, a combined cycle using a solid oxide fuel cell system, a single-stage H2O–NH3 absorption chiller and a residential hot water HX, is developed for the electricity production, hot water and cooling all at the same time, and it is studied from an exergy, energy, and exergoeconomic standpoint. Performance of system under the design condition is analyzed and the mathematical model is simulated. After analyzing the results in the initial input mode, changing the fuel cell current density effect and fuel utilization factor on the system efficiency is evaluated. The result indicates that total energy is 4.418 kW, the total exergy efficiency is 37.8%. And the overall irreversibility is 1.650 kW. On the other hand, the air HX, fuel cell and water HX are designed as elements that must be given more attention than others from the exergoeconomic perspective, because they have nearly the most amount of price compared to other parts.

Modeling water age in a full‐scale residential plumbing system

AbstractThe residence time of water in residential building water systems is a critical factor regarding water quality at end use. Published literature has highlighted the importance of water age in these systems and its relationship with pathogenic bacteria such as Legionella pneumophila. However, tools to measure water age in such plumbing systems are typically repurposed from other applications and include limitations that make them inappropriate for some plumbing systems. This work presents a novel means of estimating water age by assuming these systems operate without mixing. Data for this study was collected from a full‐scale home equipped with an extensive array of flow meters to monitor water use. Further, 408 individual water quality samples were collected to ascertain water quality changes that take place in the plumbing. Model results show weak correlation with EPANET 2.2 (ρ = 0.666), a commonly used hydraulic modeling software. The results of the water age model were also evaluated with several variable selection tools. These analyses indicate that this method's water age results are a statistically significant (p < .05) predictor of Legionella concentrations. Model results from this approach could be used in plumbing design and/or operation to assist in managing Legionella risks.

9E analysis of a flat plate solar collector system implementation: A new approach based on digital twin model coupled with global sensitivity analysis and multi-objective optimization

Flat plate solar collectors are technology with the most solar thermal energy field applications, and different studies based on artificial intelligence have been used to model these systems. This research study presents a 9E analysis based on a digital twin model coupled with global sensitivity analysis and multi-objective optimization of a solar system integrated with an array of flat plate solar collectors to satisfy residential hot water demand that represents a case study with different applications. A model based on artificial neural networks was trained, and a global sensitivity analysis using the Sobol method and a multi-objective optimization study using a genetic algorithm were also implemented. The main outcomes revealed that the digital twin model presented a high correlation above 0.99, and the 9E analysis reported a maximum value of 25.18% for thermal efficiency and 0.266% for exergetic efficiency. Also, a value of 1798.5 kgCO2/year was obtained for the amount of CO2 mitigated, $1342.9 USD for net present value, $0.0104 USD/kWh for levelized cost of energy, and 92.62, 0.519 kgCO2/year, $3.43, $1.34, and $0.00752 USD/year for energoenvironmental, exergoenvironmental, enviroeconomic energoenviroeconomic, and exergoenviroeconomic indicators, respectively. The methodology and the 9E analysis results provide a comprehensive approach that determines the optimal choice by analyzing the system's viability with different assessments and goes beyond the conventional analyses currently presented in the literature as it shows an untapped market potential for the best decision-making.

Incentive‐Stacking to Increase Water Use Efficiency

Key TakeawaysIn 2012, the Metropolitan Water District of Southern California combined its commercial and residential water conservation rebate programs into SoCal Water$mart, still in use today.Member agencies and their retail agency customers can add funding to Metropolitan's base‐level incentives for what are referred to as “stacked incentives.”Metropolitan has processes in place to allow for co‐funding flexibility, ensure rebate accuracy, and maintain agency and consumer satisfaction.

Spatio-temporal changes in urban water consumption during 2 years of the COVID-19 pandemic in southern Brazil

Abstract This study investigated the changes that occurred during the COVID-19 pandemic in urban water consumption in residential, commercial, industrial, and public agencies in the city of São Leopoldo, southern Brazil, which has about 55,000 consumers and over 200,000 inhabitants. Overall, the city increased water consumption by 5.6% during the 2-year pandemic, with 5.9% in 2020 and 5.5% in 2021. Residential and industrial consumption increased by 6.77 and 9.92% in the first year, and by 5.47 and 14.45% in the second year, respectively. On the other hand, commercial and public sector consumption decreased by 5.48 and 46.26% in the first year and 1.83 and 40.99% in the second year, respectively. In the first months of the pandemic, there was a sharp increase in residential water consumption at the same time as a reduction in consumption in the other categories. In contrast, there was a slight return to previous water consumption patterns in the following months. Overall, we can affirm that the more central neighborhoods presented higher changes in water consumption than the peripheral neighborhoods. In addition, the water consumption during the pandemic and pre-pandemic periods was statistically different for residential, industrial, and public consumers.

Designing and calibrating an agent‐based platform to evaluate the effect of climate variables on residential water demand

AbstractMany Iranian metropolises, including Shiraz, are situated in arid and semi‐arid regions, lacking sufficient renewable water resources. In recent years, climate changes, including drought and rising temperatures, have led to changes in water supply and demand. Given the necessity and importance of urban water supply, this study investigates the impact of different climate scenarios on residential water demand. Many studies, in their models, do not consider the social interactions between household water consumers and the change in their consumption behaviour, which serves as a fundamental drawback. Thus, the present research attempts to propose an agent‐based framework by modelling social interactions via the diffusion process to investigate water consumption behaviour efficiently. The model is calibrated and applied to Shiraz City in Iran, according to the data from 2006 to 2019, and it is used to simulate each scenario for the following years until 2032. The findings show that temperature has a positive and significant effect on residential water consumption; yet, rainfall negatively affects water consumption. The simulation results of these scenarios for temperature increase or decrease and rainfall changes are estimated. In addition, the developed agent‐based platform can be easily calibrated and adjusted based on the data of any other city to simulate water demand estimation under different climatic and even economic scenarios. Urban water managers can benefit from such estimates to plan future infrastructure development and proactive management of seasonal water resources under the growing pressure of potential climate change because construing the sensitivity of seasonal water consumption to climate conditions is essential to respond to variations in demand.

Design and implementation of a data-driven intelligent water heating system for an island community: A case study

Water heating accounts for approximately 25% of household energy use in developed countries. Therefore, the optimal control of water heating through the deployment of intelligent residential Electric Water Heaters (EWH) brings significant benefits. This paper presents an innovative design and implementation of an easy-to-use device for intelligent residential water heating. The device relied upon machine learning techniques to forecast a consumer’s hot water demand and optimize the operation of an EWH using a novel data collection process that relied on non-intrusive vibration data alone. The device was deployed in a six-month pilot project on the island of São Miguel, Portugal. The major difficulties were the novel use of vibration data to forecast the volume of hot water used and the uncertain behavior of the consumers. The challenges of only using vibration data were solved by careful data collection and artificial intelligence methods. To tackle the issue of uncertain consumer behavior, an innovative ‘heat now’ function was incorporated into the device to override the novel control framework. Results show that the device could accurately forecast hot water demand and optimally operate the EWH to meet this demand. The results showed an average reduction of 1.33 kWh/day per consumer, which equates to an average decrease of 35.5% in water heating costs. Calculations show that these devices can reduce the total energy used by 2832 kWh daily or 0.21% of total electricity generated. Furthermore, a fleet of these devices could reduce thermal generation by 0.37%, reducing emissions by 693.31 tons of CO2 per year. The results from the consumer survey show that the device did not affect the consumer’s comfort, validating the benefits and efficacy of the proposed device. Hence, the paper shows that a simple-to-use, novel device using an innovative forecasting algorithm based on non-intrusive vibration data brings numerous quantifiable benefits to actual consumers and electrical utilities.

Residential Water Conservation and the Rebound Effect: A Temporal Decomposition and Investigation

AbstractWater conservation in California has been a major subject of concern for agencies in their efforts to satisfy their residential demand while coping with frequent shortfalls, especially in periods of drought. During the 2012–2016 severe drought in California, the state enacted a conservation mandate that imposed specific conservation targets of 4% up to 36% for water utilities. While the utilities met those targets in 2015, water use, on average, has slowly crept up or rebounded subsequently, although not to pre‐drought levels. Understanding the manner and degree to which water use rebounds can be critically important for water utilities in their planning and investment decisions. Using a unique panel dataset on single‐family residential water use by nearly 20,000 customers of a Northern California water agency from 2013 to 2019, this paper explores the magnitude and character of the rebound effect that occurred after the cessation of a statewide conservation mandate that was imposed on water use in response a severe drought enveloping California from 2014 through 2016. Our results suggest the presence of a significant rebound in water use—of approximately 9% on average—after the conservation mandate ended. Yet, and novel to our research, we find significant heterogeneity in the rebound effects across seasons and water users, with a greater rebound in the warm season months relative to other months and among lower water use households relative to higher water use households. Our results also suggest a significant shift in water use to earlier periods of the day once the mandate was lifted. Understanding the magnitude and variation in rebound effects both temporally and across different types of water users can be useful to water agencies in their efforts to make informed decisions surrounding investments, management, and messaging in response to drought, conservation, and water scarcity.

The high health risks of unaffordable water: An in-depth exploration of pathways from water bill burden to health-related impacts in the United States

Access to clean and safe water is essential for human health and well-being, but recent and substantial increases in the cost of water for residential customers in the United States endanger the health of those who cannot afford to pay. This study identifies pathways through which unaffordable water bills may influence the behaviors and health of vulnerable people. We interviewed a sample of low-income residential water customers who were experiencing water bill hardship in Boston and Chelsea, Massachusetts, U.S. between October 2018 and December 2019. We conducted a thematic content analysis of interview transcripts. Results showed that some participants improvised ways to pay their water bills, and some confronted obstacles that made it simply impossible to pay at times. Behavioral responses to coping with high water bills were influenced by household earning potential, self-reported health status, caretaking responsibilities, and accessibility of utility assistance programs. Consequences of unaffordable household bills included reduced access to other necessities, debt accumulation, risk of water shutoff, housing insecurity, and public humiliation. Reported health-related impacts of water bill hardship were food insecurity, underutilization of healthcare and medications, and decline in mental health. Comprehensive reforms at all levels of government are needed to make water affordable for all low-income households. Federal investments in water infrastructure, state oversight of affordability and human rights, as well as municipal tiered water pricing and comprehensive assistance policies for low-income households are needed to address the growing water affordability crisis and to mitigate harm to the well-being of vulnerable residents and communities in the United States.

Activity-Wise Residential Water Use Behaviour in Aizawl City, Mizoram, India

The aim of this paper is to understand the overall household water use behaviour and activity-wise water use patterns in Aizawl city, Mizoram (India). The study is conducted in Aizawl city among 15 Local Councils out of 83 Local Councils. The number of sample households selected from each of the sample Local Councils are 50 households, thus data was gathered via questionnaire administered to 750 respondents’ mainly female household heads. The water consumption in the study area is far lower than the norms laid down by Bureau of Indian Standards. Even, in comparison to other major cities in the country, the consumption is also far deficient. The average per capita water consumption is estimated at 46 lpcd. About 38.93 per cent of the households consume water below 40 lpcd, 19.89 per cent consume between 40 lpcd to 50 lpcd, and 41.20 per cent consume water above 50 lpcd. Some household activities, like washing clothes, bathing, use in toilets, and washing dishes and utensils are the most water consuming activities in the City under focus.

Identification of the hydrochemical features, genesis, water quality and potential health hazards of groundwater in Dawen River Basin, North China

Groundwater resources fulfill a key role in socioeconomic development and residential water use in the Dawen River Basin (DRB). This study sampled and tested three types of groundwater in the DRB, including pore groundwater (PGW), fissure groundwater (FGW), and karst groundwater (KGW). Groundwater in the DRB was assessed for hydrochemical characteristics, quality, and hazards to human health by nitrate contents. Results identified the dominant groundwater anion and cation to be HCO3− and Ca2+, respectively, whereas groundwater was generally weakly alkaline hard-fresh water. The groundwater contents of main chemical components during wet season exceeded those in the dry season, with the rank of groundwater types by chemical component contents being: PGW > KGW > FGW. A Durov diagram indicated groundwater in the DRB to be mixed HCO3-Ca and HCO3·SO4–Ca·Mg types. Rock weathering (silicate and carbonate rocks) was found to be the predominant process regulating groundwater chemistry of the DRB, whereas human activities also had a significant impact, particularly for high NO3− related to agricultural activities. Groundwater quality of the DRB was relatively good overall, falling into the good and moderate classification grades, with that of the PGW the worst. Long-term human direct consumption or exposure to groundwater of DRB poses certain health risks due to groundwater nitrate, with the risk for children highest. The spatial variations in quality of groundwater and nitrate health hazard in the DRB were relatively consistent, with better quality and lower health risk of PGW and FGW in the east than in the west, and that of KGW better in the center than in the east and west. The present study can provide some reference for groundwater safety and protection management in DRB and other similar areas in the world.

Household water savings and response to dynamic incentives under nonlinear pricing

We study the response of residential water demand to nonlinear prices by exploiting a natural experiment arising from a water pricing reform in a major Chinese city. The reform introduced an unconventional Increasing Block Tariff featuring prices set according to annual cumulative consumption and a bimonthly billing cycle. Analyzing data from a household survey and administrative water bills, we detect a small effect on low-use households but find large water savings among high-use households. Moreover, we find strong evidence that high-use households respond to future price while current price remains fixed, and that the small share of households who appear myopic do not respond to dynamic incentives.

A fine is more than a price: Evidence from drought restrictions

This study evaluates whether financial penalties have non-price effects separate from any punishment avoidance behavior. I investigate the effects of a restriction termed ‘mandatory rationing’ on residential water consumers who face differential exposure to the content of the policy. I find a significant response among households who were likely to be fined, but also among households with low likelihood of facing penalties. I provide evidence that this occurs because the policy directly affected consumption through non-price channels. My findings show that fine-based policies can have impacts beyond the targeted population as a result.

Influence of the number of residents and climatic factors on residential water consumption

Abstract Water scarcity is becoming increasingly noticeable in large urban centers. Therefore, the aim of this research is to analyze the factors that influence residential water consumption in a residential building located in the city of Goiânia, Brazil, during a pre-pandemic period of 6 months. To this end, graphical analysis, trend curves, and multiple regressions were used using the R language. The sample consisted of 43 housing units with a population of one to five people in each. Once the construction aspects of the building were fixed and the water price and the type of consumption measured, it was found that the number of residents, the monthly precipitation, and the maximum daily temperature directly influence residential water consumption.

A compilation of operability and emissions performance of residential water heaters operated on blends of natural gas and hydrogen including consideration for reporting bases

The impact of hydrogen added to natural gas on the performance of commercial domestic water heating devices has been discussed in several recent papers in the literature. Much of the work focuses on performance at specific hydrogen levels (by volume) up to 20–30% as a near term blend target. In the current work, new data on several commercial devices have been obtained to help quantify upper limits based on flashback limits. In addition, results from 39 individual devices are compiled to help generalize observations regarding performance. The emphasis of this work is on emissions performance and especially NOx emissions. It is important to consider the reporting bases of the emissions numbers to avoid any unitended bias. For water heaters, the trends associated with both mass per fuel energy input and concentration-based representation are similar For carbon free fuels, bases such as 12% CO2 should be avoided. In general, the compiled data shows that NOx, NO, UHC, and CO levels decrease with increasing hydrogen percentage. The % decrease in NOx and NO is greater for low NOx devices (meaning certified to NOx <10 ng/J using premixing with excess air) compared to conventional devices (“pancake burners”, partial premixing). Further, low NOx devices appear to be able to accept greater amounts of hydrogen, above 70% hydrogen in some cases, without modification, while conventional water heaters appear limited to 40–50% hydrogen. Reporting emissions on a mass basis per unit fuel energy input is preferred to the typical dry concentration basis as the greater amount of water produced by hydrogen results in a perceived increase in NOx when hydrogen is used. While this effort summarizes emissions performance with added hydrogen, additional work is needed on transient operation, higher levels of hydrogen, system durability/reliability, and heating efficiency.

Long-Term Exposure to Nitrate and Trihalomethanes in Drinking Water and Prostate Cancer: A Multicase-Control Study in Spain (MCC-Spain).

Nitrate and trihalomethanes (THMs) in drinking water are widespread and are potential human carcinogens. We evaluated the association between drinking-water exposure to nitrate and THMs and prostate cancer. During the period 2008-2013, 697 hospital-based incident prostate cancer cases (97 aggressive tumors) and 927 population-based controls were recruited in Spain, providing information on residential histories and type of water consumed. Average nitrate and THMs levels in drinking water were linked with lifetime water consumption to calculate waterborne ingestion. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using mixed models with recruitment area as random effect. Effect modification by tumor grade (Gleason score), age, education, lifestyle, and dietary factors was explored. Mean () adult lifetime waterborne ingested nitrate (milligrams per day), brominated (Br)-THMs (micrograms per day), and chloroform (micrograms per day) were 11.5 (), 20.7 (), and 15.1 () in controls. Waterborne ingested nitrate vs. was associated with an OR of 1.74 (95% CI: 1.19, 2.54) overall, and 2.78 (95% CI: 1.23, 6.27) for tumors with Gleason scores . Associations were higher in the youngest and those with lower intakes of fiber, fruit/vegetables, and vitamin C. Waterborne ingested THMs were not associated with prostate cancer. Residential tap water levels of Br-THMs and chloroform showed, respectively, inverse and positive associations with prostate cancer. Findings suggest long-term waterborne ingested nitrate could be a risk factor of prostate cancer, particularly for aggressive tumors. High intakes of fiber, fruit/vegetables and vitamin C may lower this risk. Association with residential levels but not ingested chloroform/Br-THM may suggest inhalation and dermal routes could be relevant for prostate cancer. https://doi.org/10.1289/EHP11391.

Response of Landscape Groundcovers to Deficit Irrigation: An Assessment Based on Normalized Difference Vegetation Index and Visual Quality Rating

Developing water conservation strategies for urban landscape groundcovers grown in hot and dry summers like inland Southern California, USA, is crucial because they are one of the largest residential water users. A 2-year (2020–21) study was conducted in Riverside, CA, to assess the effect of irrigation rates on the growth of landscape groundcovers as evaluated by visual quality ratings (VR) and normalized difference vegetation index (NDVI). Relationships between VR and NDVI were also established to obtain the minimum threshold values of NDVI for each groundcover. Lastly, the groundcover water response function was developed to estimate groundcover response to irrigation rates over time. Four reference evapotranspiration (ETo)-based irrigation treatments ranging from 24% to 99% ETo and 10 landscape groundcovers were laid in a randomized complete block design and replicated three times. Data were collected from May to October in 2020 and 2021. The irrigation controller overirrigated the plots on average by 7.7% and 4.7% in 2020 and 2021, respectively. A significant relationship (P &lt; 0.05, 0.35 ≤ R2 ≤ 0.82) between NDVI and VR for each landscape groundcovers was found. On the basis of the NDVI values and VR, it was found that three landscape groundcovers, including Rhadogia spinescens, Baccharis × ‘Starn’ Thompson, Eriogonum fasciculatum ‘Warriner Lytle’ can withstand water stress and can maintain their growth and visual quality at 24% ETo irrigation. Groundcovers Ruschia lineolate nana, Rosmarinus officinalis ‘Roman Beauty’, and Eremphila glabra showed the potential to perform well with as low as 49% ETo irrigation, whereas Lantana montevidensis, Oenothera stubbei, and Lonicera japonica required 75% ETo or more.

Setting a Baseline Residential Water Demand Management Solution in Urban Towns of Ethiopia

Due to the country’s expanding population, inadequate urban water management practices, limited community knowledge of water management, and urbanization, urban water management in Ethiopia is of great importance to the administration of the country. This study draws on a qualitative and quantitative research approach to evaluate the available water supply resources and management techniques in three Ethiopian metropolitan districts, factor in the sustainability of the urban water supply services, and then recommend a workable plan for a sustainable urban water management system. Open-ended and semi-structured questionnaires were used to interview urban water utility officials to reveal important information on water demand management and current water supply services. Documented secondary data analysis and field observations are also used to identify the existing problem in order to draw future suggestions. The findings of this study indicate that some of the common issues with urban water supply systems in towns include outdated water supply infrastructures, rapid population growth and corresponding water demand, high water losses in the distribution system, poor water management practices, and a lack of appropriate institutional framework. The assessments of the three study regions demonstrate that while the percentage of water supply coverage hasn’t changed significantly over the previous 10 years, both the number of customers and the overall population growth have increased by nearly 50%. In order to address this, the Ethiopian government would need to put up a lot of effort into developing water use policies and raising consumer understanding of water demand management techniques.