Performance Analysis of a Communal Residential Rainwater System for Potable Supply: A Case Study in Brisbane, Australia

Cities in developed countries have increasingly adopted rainwater tanks as an alternative water source over the last 15 years. The rapid uptake of rainwater tanks has been driven by the need to reduce demand for centralised water services that are under pressure to adapt to population growth and climate change impacts. Rainwater tanks are part of integrated urban water management approach that considers the whole water cycle to provide water services on a fit for purpose basis that minimises the impact on the local environment and receiving waters. Rainwater tanks are typically applied at the household scale for non-potable water source uses such as toilet flushing and garden irrigation. However, this paper reports on a communal approach to rainwater harvesting, where the water is treated for potable use. A communal approach to rainwater harvesting can offer benefits, such as: economies of scale for capital costs, reduced land footprint, centralised disinfection and flexibility in matching supply and demand for different households. The analysis showed that the communal approach could provide a reliable potable water source to a small urban development. However, there was an energy penalty associated with this water source compared to centralised systems that could be addressed through more appropriate pump sizing. The outputs from this monitoring and modelling study demonstrated rainwater harvesting can be expanded beyond the current mainstream practices of household systems for non-potable use in certain development contexts. The analysis contained in this paper can be used for the improved planning and design of communal approaches to rainwater harvesting.     

A Desktop Analysis of Potable Water Savings from Internally Plumbed Rainwater Tanks in South-East Queensland,Australia

A methodology for the estimation of household potable water saving due to internally plumbed rainwater tanks (IPT) is presented in this paper. The methodology is based on a pairwise comparison of household water billing data between homes with IPT and without rainwater tanks (No Tank). These savings were compared with estimations using measured end use data and rainwater demand predictions using the Rainwater TANK model. The paper describes the application of this methodology to a case study in the south-east Queensland (SEQ) region of Australia. There was a significant reduction in mains water consumption for IPT properties in all regions studied in SEQ. Water reductions from mains supplies varied markedly across regions with mean values ranging from 20 to 95 kL/hh/y with an average mean of 50 kL/hh/y. Median water consumption values, ranged in mains water reductions from 28 to 52 kL/hh/y, with an average median of 40 kL/hh/y. Considering both measures an average water saving between 40 and 50 kL/hh/y can be expected from internally plumbed rainwater tanks. Water restrictions appear to have a strong influence on estimated reductions in mains water use. In regions where water restrictions were severe, water consumption was less varied between No Tank and IPT homes with a consequent reduction in estimated savings observed. Recommendations for further work include a survey to capture confounding factors that could not be fully controlled in the desktop study and a controlled pairwise experiment to monitor water consumption from raintanks.     

Potable Water for All: The Egyptian Experience with Rural Water Supply

ABSTRACT

Egypt during 1952–1960 achieved a more rapid and proportionately larger improvement in potable water supply for its rural population than any other developing country. The way in which this was done laid the groundwork for later difficulties in maintenance and extension of services. Similar problems arose in the Fayoum project in 1953–1964. A program for basic village services initiated in 1979 applied some of the lessons learned in the earlierprogram, but raised new environmental issues. The early change in water service was not followed by striking reductions in prevalence of childhood disease.     

Rainwater: A Potential Alternative Source for Scarce Safe Drinking and Arsenic Contaminated Water in Bangladesh

Although Bangladesh receives plenty of rainwater during its monsoon, both rural and urban areas suffer from shortages of safe drinking water during dry season. Arsenic contamination of ground water affects many rural areas, whilst some urban areas including the capital, Dhaka City, lack sufficient potable ground water to meet the demand. To cope with the problem, this research explore: the feasibility of harvesting rainwater during monsoon as a source of quality safe drinking water in Dhaka City. A questionnaire survey was conducted about potable water shortage in four slums of Dhaka City. Rainwater was collected using a non-toxic waterproof cloth as a catchment during monsoon and stored in a ferro-cement storage tank with an initial flushing device attached at the inlet of the tank. Different important physical, chemical and bacteriological parameters were tested throughout the storage period of 4 months. The efficiency of the rainwater harvesting system increased from 51% to 80% before and after installing the system. The test results were compared with the Bangladesh water quality standards. The tests have revealed slightly higher pH value (8.1 to 8.3) and enormity of color beyond the acceptable range. Although the presence of total coliform was detected after three months, traditional filtering of that stored rainwater showed a promising solution to mitigate potable water shortages in Bangladesh.     

Urban Water Demand for Service and Industrial Use: The Case of Zaragoza

Increased efforts to improve urban water management are focused on demand side policies, seeking to affect the behavior of users so that a “reasonable” use of water resources is reached. In this framework the accurate characterization of water demand play a major role in obtaining sufficient knowledge about this behavioral response to changes in price. In this paper we focus on the water demand of the services and industries connected to the public water network. To this end, we carry out an empirical estimation of urban water demand for service and industrial use in Zaragoza (Spain). The proposed model is a Koyck flow adjustment demand model, and a price specification, which is constructed as a function of the lagged average price, current marginal price and a price perception parameter. We use a dynamic panel data methodology to estimate the water demand function. As far as we are aware, this approach to service and industrial urban water demand is new in the literature. The analysis suggests that although price has a negative relationship with consumption, such an effect is reduced given that the price elasticity is lower than one in absolute value. Another relevant finding is that service and industrial urban users think that they pay a lower price than the actual price they pay.     

The Effects of Groundwater and Surface Water Use on Total Water Availability and Implications for Water Management: The Case of Lake Naivasha, Kenya

This study discusses the effects of water abstractions from two alternative sources on the available water volume around Lake Naivasha, Kenya: the lake itself and a connected aquifer. An estimation of the water abstraction pattern for the period 1999–2010 is made and its effect on the available water volume in Lake Naivasha and its connected aquifer is evaluated using a simple water balance modeling approach. This study shows that accurate estimates of annual volume changes of Lake Naivasha can be made using a simple monthly water balance approach that takes into account the exchange of water between the lake and its connected aquifer. The amount of water that is used for irrigation in the area around Lake Naivasha has a substantial adverse effect on the availability of water. Simulation results of our simple water balance model suggests that abstractions from groundwater affect the lake volume less than direct abstractions from the lake. Groundwater volumes, in contrast, are much more affected by groundwater abstractions and therefore lead to much lower groundwater levels. Moreover, when groundwater is used instead of surface water, evaporation losses from the lake are potentially higher due to a larger lake surface area. If that would be the case then the overall water availability in the area is more strongly affected by the abstraction of groundwater than by the abstraction of surface water. Therefore water managers should be cautious when using lake levels as the only indicator of water availability for restricting water abstractions.     

The Economics of Urban Water Demand: The Case of Industrial and Commercial Water Use in Hawaii

The industrial and commercial establishments of the City and County of Honolulu (CCH) have increased their water consumption dramatically in recent years. This study examined water use in the food-processing industry, non-food processing industries, and the commercial sector in relation to price of water and output/sales of the industrial or commercial unit. The generalized least-squares (GLS) procedure was used to estimate the regression equations, although the results of ordinary least-squares(OLS) estimation are also presented. The study results showed sensitivity of water use in relation to price level in the case of the food-processingindustry and insensitivity in the non-food processing and commercial establishments. Analogous results were found with respect to water use and number of employees.     

Assessment of Rainwater Availability by Building Type and Water Use Through GIS-based Scenario Analysis

Scenario analysis of rainwater harvesting and utilization (RWHU) was performed considering various non-potable water uses in different building types over a year. Six building types were identified in the study area using GIS data: residential houses, offices, commercial buildings, restaurants, public buildings, and “others”. Rainwater storage capacity was considered as 30 mm rainwater depth. Water demand for each building type was calculated as the sum of the individual water uses for toilet flushing, air conditioning, garden irrigation, and cleaning defined in this study as “miscellaneous usages”. To incorporate water quality considerations, rainwater with suspended solids level of less than 2 mg l⁻¹ was used as the quality criterion. The RWHU scenario was compared with other storage and water use scenarios. This study quantified the rainwater availability throughout a year and its seasonal variation and consumption in each building type. The analysis clarified the effectiveness of rainwater utilization for supplementing existing water resources.     

Conjunctive Water Use Optimization for Watershed-Lake Water Distribution System under Uncertainty: a Case Study

Water Resources Management - In this research, a large-scale inexact optimization method was developed for the conjunctive use management of a watershed-lake water distribution system. The modeling...     

Modeling the Effect of Cistern Size,Soil Type,and Irrigation Scheduling on Rainwater Harvesting as a Stormwater Control Measure

Urban stormwater runoff could have negative impacts on water resources and the environment. Rainwater Harvesting (RWH) can serve both as a stormwater control and water conservation measure. Cistern size and irrigation scheduling are two of the factors that directly impact the total runoff from a residential unit with a RWH system and the amount of potable water used for irrigation. The effectiveness of RWH was evaluated for four soil types; Sand, Sandy Loam, Loamy Sand, and Silty Clay, with a root zone of 15.2 cm using three irrigation scheduling methods (Evapotranspiration (ET)-based, soil moisture-based, and time-based), and five cistern sizes. Total runoff volumes and total supplemental potable water used were compared among the three irrigation scheduling systems and a control treatment without RWH. A model was developed to simulate the daily water balance for the treatments. Irrigation and runoff volumes were compared for the various scenarios. Silty clay soil resulted with 83 % more runoff than Sandy soil, while Sandy soil required on average 58 % more supplemental water than Silty Clay soil. On average, the 833 L cistern resulted with 41 % savings in water supply and 45 % reduction in total runoff. Results showed that the greatest volumes of runoff predicted were for the silty clay soil Control Treatment using a time-based irrigation scheduling method, while the least volumes calculated were for the sandy loam soil time-based irrigation scheduling treatment with 833 L cistern size. The greatest volumes of total supplemental water predicted were for sandy loam soil Control Treatment, while the least volumes were for silty clay soil ET-based irrigation scheduling treatment with 833 L cistern size. Regression equations were developed to allow for users to select a RWH cistern size based on the amount of water they want to save or runoff to reduce.     

Public Sector Alternatives to Water Supply and Sewerage Privatization: Case Studies

The paper presents a consideration of public sector operations as an alternative to the privatization of water and sewerage services. Cross-country case studies of publicly owned enterprises which have succeeded in reconciling efficiency and social purposes and carrying out structural and managerial changes are compared with some experiences of privatized concessions. Overall, public enterprises appear no less efficient that private companies, while being capable of development-oriented consideration of public interests.     

Inadequacy of Land Use and Impervious Area Fraction for Determining Urban Stormwater Quality

Urban stormwater quality is multifaceted and the use of a limited number of factors to represent catchment characteristics may not be adequate to explain the complexity of water quality response to a rainfall event or site-to-site differences in stormwater quality modelling. This paper presents the outcomes of a research study which investigated the adequacy of using land use and impervious area fraction only, to represent catchment characteristics in urban stormwater quality modelling. The research outcomes confirmed the inadequacy of the use of these two parameters alone to represent urban catchment characteristics in stormwater quality prediction. Urban form also needs to be taken into consideration as it was found have an important impact on stormwater quality by influencing pollutant generation, build-up and wash-off. Urban form refers to characteristics related to an urban development such as road layout, spatial distribution of urban areas and urban design features.     

Understanding Municipal Water Use and Data Availability: a Case Study across North Dakota,USA

Water Resources Management - Tremendous variation exists in how cities, states, countries, and other jurisdictional areas classify water use and consumption. Additionally, water conservation...     

Of Dreamliners and Drinking Water: Developing Risk Regulation and a Safety Culture for Direct Potable Reuse

Direct potable water reuse (DPR), the injection of highly purified wastewater into drinking water systems, is among the newest, and most controversial, methods for augmenting water supplies. DPR is garnering increasing interest, but does not come without risks. This paper examines the notion that emerging regulation of DPR may lack sufficient attention to a particular class of risks: catastrophic risks with low probabilities of occurrence, but high consequences. It may be instructive for proponents of DPR that such consequences have materialized in other industries, with damage to human welfare and to the industries themselves. We develop brief histories of risk regulation from the aviation, offshore oil, and nuclear industries, drawing out relevant lessons for the emerging DPR field. We argue that proponents of DPR could benefit from proactively developing a safety culture in DPR utilities and establishing an effective industry-wide auditing organization that investigates unanticipated system failures. Developing independent oversight for DPR operation could ensure that stringent quality and management requirements are set and enforced, and that any system failures or “near misses” are investigated and adequately responded to.     

The Economics of Household Demand for Water: The Case of Kandy Municipality,Sri Lanka

This study estimates the demand for domestic water in a fast-growing city of a developing country. Monthly data for 40 randomly selected households for a six-year period were used for the estimation. There were three price hikes during the study period, which provided adequate variation in the prices for an econometric estimation. A log-log model was selected as a proper specification for the demand function. Marginal price, difference price, income, and household size were used as the independent variables. After correcting the data for auto-correlation and heteroscedasticity, the final model was estimated. Results show all the expected signs with statistical significance. Price elasticity (marginal) and income elasticity for water in the study area are estimated to be - 0.34 and 0.08, respectively. Thus, our findings confirm the previous findings that water is neither price- nor income-elastic. Given these responses, a price hike may not help conserve water in the study area. However, very low price responsiveness can be used to increase water revenues of the municipality.     

Water Balance Approach for Rainwater Harvesting using Remote Sensing and GIS Techniques, Jammu Himalaya, India

Judicious use of the limited fresh water resources is the need of the hour. If sufficient measures are not taken up immediately, we will face a crisis which will be detrimental to the very survival of mankind. The Kandi region of Jammu district in Jammu Himalaya is facing a similar problem of acute shortage of drinking water. One of the most logical steps towards this goal would be acknowledging the importance of rainwater harvesting. The Central Ground Water Board (CGWB), North Western Himalayan Region, Jammu, has already initiated few schemes to recharge and conserve the water resources. The water resources in this study area have been estimated by water balance assessment approach. The water balance study using the Thornthwaite and Mather (TM) models with the help of remote sensing and GIS is very helpful in finding out the moisture deficit and moisture surplus for an entire watershed. The water balance calculation shows that the maximum annual runoff results from the built-up areas/water body followed by agricultural land, dense forest and minimum for the barren land and open forest. The annual deficit in the Devak–Rui watershed is 0.38 mm and the annual surplus is 1,251.34 mm. GIS software’s have been used for spatial analysis for generation of various thematic layers and integration to produce the final runoff map. The total runoff of Devak–Rui watershed was calculated as 1,160.48 mm from the total precipitation of 1,429.26 mm. It was found that suitable sites for rainwater harvesting structures in the Devak–Rui watershed covers an area of nearly 11% of the watershed area whereas the rest of the watershed area was assumed as unsuitable site for rainwater harvesting.     

小型雨水积蓄工程“水窖”的施工

本文介绍了一种集雨水窖的结构型式 ,施工方法 ,注意的问题 ,及资金和劳力的来源     

创新思维 推进雨水集蓄利用 兴水调产 夯实现代农业根基

<正>寿阳县位于太行山西麓,晋中市东部,国土总面积2110km2,现辖14个乡镇,206个行政村,22万人。境内山峦起伏,沟壑纵横,气候干燥,十年九旱,是一个典型的丘陵山区县份,全县多年平均降雨量为500mm,且主要集中在7—9月,春季降雨仅占全年总     

Complementary Water Systems in Dar es Salaam,Tanzania: The Case of Water Vending

In many cities in developing countries, a piped water supply is the norm for richer households, while poorer households struggle with a number of alternative means for accessing water. In Dar es Salaam, as the public water supply is highly deficient, households of all income classes draw upon a variety of water sources. Distribution by container using pushcarts is common in large areas, in particular where piped water is rationed, low pressure or non-existent. Tankers complement the public supply in wealthier areas. This paper focuses on how public and private systems complement one another with regards to pushcart water distribution.     

金沙县农村饮用水安全与地下水开发的分析与探讨

由于金沙县特殊的自然环境和地形地质条件,当地的水资源的开发与利用十分困难。根据调查饮水不安全资料表明,全县饮水不安全人口总数达22.21万人,占全县总人口的37%。在分析金沙县农村饮水安全现状、存在的问题等基础上,以贵州省金沙县长坝乡硐口地下河开发利用示范为例,强调地下水开发利用在解决农村饮水安全工作中地位。