Small Water Supply Research Articles

Comparison of passive and manual chlorination in small piped water networks in rural Ghana: Technical performance, ease-of-use, and cost

Chlorination is the most common water treatment method globally and leads to proven health benefits. Yet, many rural water supplies in low-income settings are unchlorinated, exposing consumers to waterborne diseases. Insufficient technical and financial capacity of water suppliers in low-resource settings are common barriers to more widespread chlorination. We conducted a case study of two approaches to chlorinate small piped water supplies− passive (inline) chlorination and manual chlorination− and compared their technical performance, ease-of-use, and costs in rural Ghana. Based on 685 water quality measurements across two piped networks over three months, both methods provided adequate free chlorine residuals (i.e., 0.2–2.0 mg/L) most of the time (71% for manual chlorination and 86% for passive chlorination). Follow-up measurements five months later revealed a decline in chlorine levels with the manual approach (47% in the target range) and an increase with the passive (inline) approach (100% in the target range). We observed large fluctuations in chlorine levels over time, particularly with inline chlorination, that pH, temperature, conductivity, and turbidity variations did not fully explain. Temporal changes in chlorine demand and/or inconsistently implemented protocols possibly contributed to these fluctuations. Inline chlorination scored higher for ease-of-use (85%) than manual chlorination (70%) but was less financially viable: it represented an 11% increase in operational expenses, compared to 4% for manual chlorination. Initial equipment and installation cost approximately 6,000 USD for inline chlorination and about 260 USD for manual chlorination. Our results highlight the tradeoffs between passive (inline) and manual chlorination. Although less favorable for ease-of-use, manual chlorination is more viable financially and can achieve comparable performance with strict dosing protocol adherence, suggesting this approach deserves similar consideration as passive chlorination when evaluating options for low-resource settings. Both methods are susceptible to changes in operator behaviors and require external oversight plus support for troubleshooting and recalibration.

Analysis of water losses in seven small and medium-sized water distribution networks in the south region of Cameroon (Central Africa)

ABSTRACT This paper analyzes and evaluates water losses in seven small and medium-sized water supply networks (WSNs) in the south region of Cameroon in order to contribute to improving the most effective approaches to reducing water losses in Sub-Saharan Africa's WSNs. Data were obtained from the regional delegation of the Camwater in the south region of Cameroon and analyzed using a variety of indices, including the failure intensity index, the unit coefficient of water loss per kilometer, the real leakage balance index, the non-revenue water basic, and the infrastructure leakage index. Results indicate that all the WSNs analyzed achieved mixed results compared with national data and very weak results compared with international standards. This is partly due to outdated infrastructure, rapid urbanization and urban population expansion, poor operation and maintenance policies, inadequate technical skills and technology, a lack of financial discipline, and political, cultural, and social influences. The results place the cumulative volume of water losses in the seven networks studied during the 5 years at 7.3 million cubic meters, which costs the water utility about 2.4 billion FCFA (or 4.4 million USD).

Two-year Monitoring of Microbiological Water Quality in Small Water Supply Systems: Implications for Microbial Risk Management.

Small water supply systems (SWSSs) are often more vulnerable to waterborne disease outbreaks. In Japan, many SWSSs operate without regulation under the Waterworks Law, yet there is limited investigation into microbial contamination and the associated health risks. In this study, the microbiological water quality of four SWSSs that utilize mountain streams as water sources and do not install water treatment facilities were monitored for over 2 years. In investigated SWSSs, the mean heterotrophic plate counts were below 350 CFU/mL, and the total bacterial loads (16S rDNA concentration) ranged from 4.71 to 5.35 log10 copies/mL. The results also showed the consistent presence of fecal indicator bacteria (FIB), i.e., Escherichia coli and Clostridium perfringens, suggesting the potential of fecal pollution. E. coli was then utilized as an indicator to assess the health risk posed by E. coli O157:H7 and Campylobacter jejuni. The results indicated that the estimated mean annual risk of infection and disability-adjusted life years (DALYs) exceeded acceptable levels in all SWSSs for the two reference pathogens. To ensure microbial water safety, implementing appropriate water treatment facilities with an estimated mean required reduction of 5-6 log10 was necessary. This study highlighted the potential microbial contamination and health risk level in SWSSs that utilize mountain streams as water sources, even though the water sources were almost not affected by human activities. Furthermore, this study would also be helpful in supporting risk-based water management to ensure a safe water supply in SWSSs.

Climate resilience of small-town water utilities in Eastern Ethiopia

Climate change threatens the safety of water supplies globally, but small water supplies in rapidly growing and urbanizing towns in low- and middle-income countries are especially at risk. Despite the efforts of the Government of Ethiopia, research shows that that small-town water utilities in Ethiopia are poorly equipped to prioritize developing and maintaining climate-resilient water services. We applied the How tough is WASH framework for climate resilient water supplies to ten town water utilities in Eastern Ethiopia to identify their strengths and weaknesses in preparing for climate change. We found reports of weak institutional support from service authorities and exclusion of climate risk management from trainings, which cascades down to service providers in the form of lack of emergency response, inadequate staffing and financial mismanagement. This is consistent with previous studies on sustainability of town water utilities, and highlights the applicability of this tool into existing monitoring frameworks that have been proposed for town water utilities in Ethiopia. We also modified the How tough is WASH framework to capture these findings and better reflect the complexity of a utility-managed piped water supply.

Technical and economic impact of water reuse as an integrated water resource management measure in rural water supply systems

ABSTRACT Water reuse becomes an alternative to reduce the demand in the conventional water supply systems, especially in regions, where non-potable use of drinking water, as for garden and grass irrigation, is predominant. This study evaluates the footprint of reuse on small water supply systems in rural areas, where raw water quality does not meet the drinking water standards and complicated treatment is needed. Individual facilities for reuse of potential rainwater, light gray, gray and domestic wastewater in the households could lead to a decrease in non-potable tap water use up to 60% and a decrease of households' annual expenses for water supply up to 93 €/household. The installation of individual facilities for common reuse of rainwater and gray wastewater requires the highest investment costs, but the option`s operational costs are between 15% and 20% lower than all other options considered. The Drinking Water Treatment Plant capacity reduction due to Integrated Water Resource Management measures implementation enables from 48% up to 58% saving in the total operational costs for drinking water supply in the settlement. The shortest payback period and best economic impact of reuse for small scale water supply systems is observed if rainwater and gray wastewater are reused together.

Future projection of water resources based on digitalisation and open data in a water-rich region: a case study of the city of Klagenfurt

ABSTRACT Implementation of different strategies on the demand and supply side to deal with potential water scarcity is based on a comparison of future water demand and availability of water resources based on different scenarios of climate change and population growth. Especially, the Alpine region is characterised by many small and medium water supply systems (WSSs) having neither human resources nor time for advanced planning, requiring simple methods for estimating future development. Therefore, the aim of this work is to provide future projections of water demand, resource availability, and drinking water quality for an Alpine area based on simple approaches with minimal data requirements. As the results of the case study show, linear and polynomial regression with precipitation and temperature data can illustrate the temporal variation of system input and drinking water temperature with sufficient accuracy and is suitable for an estimation of future development. The groundwater modelling, however, requires the consideration of a non-linear term depending on the depth to obtain reasonable results. Due to the usage of open-access data and the easy approaches developed and applied, a good transferability to other case studies is expected which can provide stakeholders a first assessment of the future need for action.

Small water supply system with plasma-modified poly(tetrafluoroethylene) membrane for drinking water production

The small water supply systems aim at supplying safe drinking water to small communities in remote areas. This study applies an automatic small water supply system comprising 20 plasma-grafted poly(tetrafluoroethylene) (PTFE) membranes with a 1.42 m2 filtration area to generate permeate at a capacity of 3 m3/day from raw water collected from a local river. The system was tested by 34 days in phase I with bubble scraping and by 120 days in phase II without bubbling, with water quality, cross-membrane pressure drops, and dissolved organic carbons’ and foulants’ characteristics being recorded. Even with typhoon water turbidity up to 1714 nephelometric turbidity units (NTU), the system yields drinking water, meeting Taiwan’s standards. The system is fully automatic with no coagulant or disinfectant doses; an operational cost of 0.21 USD/m3 is proposed, much lower than the tariffs applied in most countries. The foulant characteristics and washing efficiencies noted are discussed.

Ceramic nanoparticle based flexible hydrovoltaic devices for tactile and respiratory signal detection

Devices that utilize water evaporation or moisture to generate electricity have received significant research attention in the field of energy conversion and harvesting. Herein, a device capable of generating electricity through the process of water evaporation has been created, utilizing medical nonwoven fabric as a porous substrate with simple dip-coating and spray-coating techniques. The device constructs a multitude of nanopores on the substrate by employing a blend of Al2O3 nanoparticles of varying dimensions. The electrical output of the device was stable at 0.55 V and 6 μA from a small water supply, as confirmed by the test. The device can easily recognize the click of a finger through the release of minuscule amounts of water during the contact. Furthermore, the device has the ability to recognize various breathing patterns, such as normal breathing, rapid breathing, and wheezing that may induced by diseases. This work developed a flexible device for power generation by water evaporation process and provides a referable idea for human related humidity sensing.

Implementing risk-based approaches to improve drinking water quality in small water supplies in the Nordic region - barriers and solutions.

Small water supplies face similar problems worldwide, regardless of ownership or management type. Non-compliance with water quality regulations is more frequent in small supplies than in large ones, as are waterborne disease outbreaks. The new European Union Drinking Water Directive requires risk-based approach (RBA) to secure water safety as is recommended in the World Health Organization's Guidelines for drinking water quality through 'water safety plans'. This is already in regulation in the Nordic countries, although less used in small supplies. In this research, we explore the challenges, barriers and possible solutions to implementing RBA and improving compliance in small supplies. This was achieved by conducting and analysing interviews with 53 stakeholders from all eight Nordic countries to produce recommendations for action by the different implicated actors. Our findings suggest the centrality of governmental policy, including support for continuous training, provision of simple RBA guidelines and increasing cooperation in the water sector. The Nordic experience reflects global challenges with small water supplies and the trend towards systematic preventive management epitomized in the framework for drinking water safety advocated by the World Health Organization since 2004.

Motivation, robustness and benefits of water commons: Insights from small drinking water supply systems

The article addresses the governance of water commons with an emphasis on drinking water. The study applied two conceptual frameworks: Ostrom's Design Principles and the Social-Ecological Systems framework. The empirical part refers to two water commons in Slovenia and is based on qualitative data from semi-structured interviews with locals and professionals. The article follows three objectives: 1) to identify the drivers and motivations for successful local water governance; 2) to assess the robustness of water commons in terms of current and future challenges; 3) to identify the benefits of water commons. The key elements for the functioning of the two local communities under examination are shared interests, as well as a strong commitment to effective management. In addition to the material benefits (i.e. drinking water supply), non-material ones are also important. Community building and identity are particularly noteworthy. The importance of small drinking water supply systems that are well organised and responsibly governed as commons is beneficial not only to a municipality but also to a country.

The relationship between water pressure variations and drinking-water quality in small water supplies: A case of Mukono District, Uganda

The supply of a safe and adequate quantity of water is essential for human health and socioeconomic development. Physiochemical and microbiological quality of water supplied in piped distribution systems can be affected by long water residence times and travel distances. This may be due to low pressure, reservoir storage and insufficient disinfection in the system among other causes. As such, large schemes usually have mechanisms of improving the quality of water along supply and/or distribution networks at reservoir and other points. In contrast, small, piped water supply schemes rarely have the infrastructure and resources to monitor and provide treatment to the water in distribution. The objective of this study was to assess the variation of water quality and water pressure along the supply network in small, piped water systems. The study used mixed methods of quantitative water quality and pressure assessments, alongside stakeholder interviews, to investigate the variability of water pressure and specific water quality parameters across the distribution network, and reliability of supply in two different small water supply schemes in the study area of Mukono, Uganda. Results showed water pressure in small, piped water supply networks have minimal influence on variation of selected water quality parameters in smaller (< 4000 m travel distances) and well operated and maintained systems. A pressure drop from 82.2 m to 22.5 m changed Turbidity by < 1, Apparent Color by < x10 and Total Dissolved Solids by < x102. Proper management of supply systems to ensure optimal residual and continuous pressure can safeguard the quality of water in the distribution systems of small piped water networks against intrusion of contaminants. Good management practice that utilizes historical operational data with continuous capacity development and training support on water quality and pressure fluctuations can significantly improve system performance to meet acceptable standards.

Analysis of Intermittent Water Distribution Networks Using a Dummy Emitter Device at Each Demand Node

The pipe component of a water distribution network (WDN) is sized based on the fixed design demand considering a peak factor and design period. Simulation of the designed network by a hydraulic solver provides nodal pressure head, head loss, velocity, and flow in each pipe as the prime outputs for the design demand, and it can also be used for extended-period simulation for a particular demand pattern over the supply hours. But, in reality, the behavior of the network does not match with such a result in an intermittent water supply (IWS) system due to the fact that all house service connections behave as an uncontrolled orifice. This has made it a challenging task in understanding and in predicting the behavior of the networks by the municipal engineer once the water starts flowing through the house service connections (HSCs). Though the municipal engineer provides the same pipe size for HSCs to all residences, the flow received by each house could vary based on the available pressure head at the ferrule point of the main water supply pipeline. In reality, maintaining constant pressure at each HSC is not feasible due to frictional head loss. Hence, variation in flow at the HSC is inevitable even with a small water supply system. This paper illustrates how to simulate the behavior of an IWS system based on the number of HSCs provided to each pipeline using a hydraulic solver. Hydraulic simulation of the water distribution network that provides IWS to consumers can be implemented easily by adding a fictitious node by assigning an appropriate emitter coefficient to each demand node through a fictitious link having a check valve in it. The method for finding the appropriate value of the emitter coefficient that helps in simulating HSCs is illustrated in the present work.

Situation analysis of drinking water quality and sanitary conditions in small scale water supply systems in rural areas in Serbia

Situation analysis of drinking water quality and sanitary conditions in small scale water supply systems in rural areas in Serbia

The drainage of glacier and ice sheet surface lakes

Supraglacial lakes play a central role in storing melt water, enhancing surface melt and ultimately in driving ice flow and ice shelf melt through injecting water into the subglacial environment and through facilitating fracturing. Here, we develop a model for the drainage of supraglacial lakes through the dissipation-driven incision of a surface channel. The model consists of the St Venant equations for flow in the channel, fed by an upstream lake reservoir, coupled with an equation for the evolution of channel elevation due to advection, uplift and downward melting. After reduction to a ‘stream power’-type hyperbolic model, we show that lake drainage occurs above a critical rate of water supply to the lake due to the backward migration of a shock that incises the lake seal. The critical water supply rate depends on advection velocity and uplift (or more precisely, drawdown downstream of the lake) as well as model parameters such as channel wall roughness and the parameters defining the relationship between channel cross-section and wetted perimeter. Once lake drainage does occur, it can either continue until the lake is empty, or terminate early, leading to oscillatory cycles of lake filling and draining, with the latter favoured by large lake volumes and relatively small water supply rates.

Ground water resources of Azerbaijan and their efficient use

The paper is dedicated to the surface water resources of Azerbaijan and their efficient use. Azerbaijan is in the list of the countries with small water supply. Compared to the other countries of the South Caucasus, the water resources of Azerbaijan are limited and comprise only 15 % of water resources of the whole region. The water percent per head of the population in Azerbaijan is on the lowest level compared to the other Republics. The main reason for this is various locations of water sources. The estimated reserves of water in our country are equal to 30.9 bln. m3, of which 33 % is local, and 66 % - the water formed due to the transborder rivers. The contamination of Araz and Kur rivers, the major water sources, by the neighboring states worsens the situation. To meet the demand of the crop plants in irrigation water, the amount of the agricultural water should be increased. Therefore, the supply of farm lands with water is directed to the implementation of the different water-related activities, as well as to the engineering-melioration and other organizational issues with the purpose of rational use of the water.

Determination of Seasonal Indices for the Regionalization of Low Flows in the Upper Vistula River Basin

Low flow is a parameter that is used for many purposes in water management. It is particularly important in terms of the needs of small water supply systems, which usually are located in ungauged catchment areas. The aim of this study is to determine the values of seasonality indices for the regionalization of low flow characteristics in the Upper Vistula river basin. This study analyzed three seasonality indicators (seasonality index—SI; seasonality histograms—SHs; and seasonality ratio—SR) in 32 selected catchments differentiated in terms of selected physiographic and meteorological characteristics. Daily flows, from the years 1951–2016, were used in the study. On the basis of the analysis, regions characterized by similar values of seasonality indicators were delineated. The non-hierarchical method of cluster analysis, i.e., the K-means method, was used for this purpose. For each region, obtained by this method, regression models were determined using stepwise regression analysis. Three groups of low flow occurrences were determined: winter, summer and mixed. The delineation of an additional mixed group for the Upper Vistula river basin resulted in a much better fit of calculated flows to observed values than in the case when only two groups of low flow seasonality were determined (winter and summer).

Remote Monitoring of a Small Water Supply Facility via Simple Radio Modules Based on Low-Power Wide-Area (LPWA) Network Technologies

Remote Monitoring of a Small Water Supply Facility via Simple Radio Modules Based on Low-Power Wide-Area (LPWA) Network Technologies

Drinking water quality as a risk factor for pupils’ health in rural schools in Serbia

Abstract Background Access to safe drinking water in schools is essential for a good health, wellbeing, learning and dignity of pupils. The rural schools are most frequently connected to the rural water supply system or own water supply source, where the monitoring of drinking water quality is scarced. The study was conducted in the rural regions in Serbia in 2016, aiming at assessing drinking water quality and sanitary conditions of school water supply facilities. Methods In total 238 school facilities, including 108 in Šumadija and 130 in Pomoravlje District were investigated using laboratory testing of drinking water and sanitary inspection. Results Study revealed that 32% of analysed samples showed microbiological faecal contamination with bacteria E. coli, while 52% of samples showed physico-chemical non-compliance with the national standards, where higher nitrates were the most common cause. Overall non-compliance of drinking water from school rural water supply systems amounted to 66% of tested water samples. This study also showed the main technical shortcomings of school water supply facilities and distribution networks such as the lack of fencing of the water source, damaged or absence of drainage channels from the well concrete floor and poor construction characteristics of wells. Conclusions The results of this study, particularly presence of E. coli in drinking water may affect pupils’ health and is a consequence of poor sanitary conditions and maintenance of small rural drinking water supply systems and individual wells. It is necessary to provide continuous disinfection of water available in schools and to undertake measures for technical improvements in order to provide better sanitary protection of water sources and other water supply facilities in rural schools. Key messages • Drinking water quality in schools is vital for children public health. • Raise awareness of local community on drinking water safety and enforce continuous monitoring of drinking water quality in small rural water supply systems in schools.

Identification of Suitable Locations in a Small Water Supply Network for the Placement of Water Quality Sensors Based on Different Criteria under Demand-Driven Conditions

Drinking water quality monitoring in real time is of utmost importance to ensure public health. Although water utilities, following the related legislative framework, monitor drinking water quality through samplings, the likelihood of detecting contaminants in consumers’ taps is low, depending on the scale of the monitoring programme. Additionally, even if the monitoring frequency is high, there is a time delay since sampling and analysis processes take some time. The selection of suitable locations for the installation of online water quality sensors is a hard task for a water utility due to the complexity of the water distribution system, the limitations of certain network junctions which are not easily accessible, and the computational burden involved. This topic has been extensively studied in recent years and sophisticated methods have been developed using optimization techniques. However, small water utilities do not have the means to implement such tools. This paper applies a methodology to identify the suitable junctions for the installation of online water quality sensors based on different objectives and under demand-driven conditions. This paper utilizes the hydraulic simulation model of a standard network to set up the water quality simulation model. A thorough analysis of various contamination scenarios takes place with different injection nodes and at different starting injection times for 24 h. The latter relates to the contaminant’s spread due to varying water demand. After a thorough analysis of 816 scenarios, a prioritized list of the most suitable nodes for the installation of the sensors is available for each optimization objective. Comparing the prioritized list of nodes achieved from each single or multi-objective function, the detection probability is almost the same. The analysis revealed that, due to varying water demand conditions, the ranking of the proposed nodes suitable for the installation of water quality monitoring sensors differs. Thus, varying hourly water demand should be part of analyses seeking to get reliable results.

Adapting sanitary inspections for the monitoring of small drinking water supplies in Iceland

Sanitary inspections (SIs) are checklists of questions used to identify actual and potential sources and pathways of drinking water contamination. Though the importance of SI adaptation to local contexts is widely acknowledged, there is currently limited guidance on how this should be undertaken in practice. During this research, World Health Organization (WHO) draft template SI forms for spring and borehole supplies were adapted for use in Iceland based on a series of desk reviews and field tests, an approach which may guide other future SI adaptation processes. SI results were collected from 25 spring supplies and nine borehole supplies in three regions of Iceland using adapted SI forms. These results were combined with 10-year historical water quality data from the same supplies to explore potential relationships between both data sets. Binary logistic regression test results indicated a statistically significant association (P = 0.025; odds ratio (OR) 1.864, 95% CI 1.080-3.220) between SI Question 3 (Does ponding from surface water occur around the spring/borehole?) receiving a 'High' risk level assignment and at least one historical incidence of water quality noncompliance for the parameters heterotrophic plate count 22 °C, total coliforms, Escherichia coli, and turbidity at the same supply. The significant modifications applied to the starting template during the testing and development of the Icelandic SI form emphasises the importance of a robust adaptation process to ensure SI forms are appropriate for the local context. Results from the analysis of SI and water quality test results demonstrated the potential for these data sets to identify the primary risks at a supply. This information may then be used to direct remedial actions, especially when the amount of relevant data increases over time.