Rainwater tank capacity and potential for potable water savings by using rainwater in the residential sector of southeastern Brazil

Rainwater has been used in many countries as a way of minimising water availability problems. In Brazil, it has been reported that the potential for potable water savings by using rainwater may range from 48% to 100% depending on the geographic region. In southeastern Brazil, water availability is about 4500 m³ per capita per year, but it is predicted to be lower than 1000 m³ per capita per year from about 2100 onwards. The main objective of this article is to evaluate the potential for potable water savings by using rainwater in 195 cities located in southeastern Brazil. Rainwater tank sizes are also assessed for some cities in order to evaluate the ideal tank capacity as a function of potable water demand and rainwater demand. Results indicate that average potential for potable water savings range from 12% to 79% per year for the cities analysed. Ideal rainwater tank capacities for dwellings with low potable water demand range from about 2000 to 20,000 litres depending on rainwater demand. For dwellings with high potable water demand, ideal rainwater tank capacities range from about 3000 to 7000 litres. The main conclusion drawn from the research is that the average potential for potable water savings in southeastern Brazil is 41%. It was also concluded that rainwater tank capacity has to be determined for each location and dwelling as it depends strongly on potable water demand and rainwater demand.     

Potential for potable water savings by combining the use of rainwater and greywater in houses in southern Brazil

Research on rainwater and greywater have been performed all over the world as a way of promoting potable water savings. The main objective of this article is to evaluate the potential for potable water savings by using rainwater and greywater in two houses in southern Brazil. An economic analysis is performed to evaluate the benefits of using rainwater and greywater either separately or together. Results indicate that the potential for potable water savings in both houses range from 33.8% (house B) to 36.6% (house A), considering that water for toilet flushing and washing machine does not need to be potable. By using rainwater, the potable water savings in house A would be 35.5% and in house B, 33.6%. When greywater is considered alone, potable water savings are lower, i.e., 30.4% in house A and 25.6% in house B. As for the use of rainwater and greywater combined, the potable water savings are 36.4% in house A and 33.8% in house B. The three systems that were investigated seem not to be cost effective as the payback periods were very high (above 17 years), but the greywater system was the most attractive one. The main conclusion that can be made from the research is that there needs to be government incentives in order to promote the use of rainwater or greywater in houses in southern Brazil.     

Potential for potable water savings by using rainwater and greywater in a multi-storey residential building in southern Brazil

Studies on the use of rainwater and greywater to promote potable water savings have been performed in different countries. The main objective of this article is to evaluate the potential for potable water savings by using rainwater and greywater in a multi-storey residential building composed of three blocks, located in Florianópolis, southern Brazil. Water end-uses were estimated by applying questionnaires and measuring water flow rates. An economic analysis was performed to evaluate the cost effectiveness of using rainwater and greywater either separately or together. Results show that the average potential for potable water savings range from 39.2% to 42.7% amongst the three blocks, considering that water for toilet flushing, clothes washing and cleaning does not need to be potable. By using rainwater, the potable water savings would actually range from 14.7% to 17.7%. When greywater is considered alone, potable water savings are higher, i.e., ranging from 28.7% to 34.8%. As for the use of rainwater and greywater combined, the potable water savings range from 36.7% to 42.0%. The main conclusion that can be made from the research is that the three systems that were investigated are cost effective as the payback periods were lower than 8 years, but the greywater system was the most cost effective one, followed closely by the rainwater one.     

Spatial and numerical analysis of the parameters influencing potential for potable water savings made using rainwater harvesting: case of the Paris agglomeration

The quantity of Potential for Potable Water Savings (PPWS) made using rainwater harvesting differs between municipalities within the same region. Three main parameters contribute to this difference: roof area, the number of inhabitants and rainwater use scenarios. This article proposes a spatial and numerical analysis of how these parameters influence PPWS across municipalities in the Paris agglomeration. A comparison between the location of the municipalities, the PPWS value and the values for the previous parameters was used to understand the observed difference. The spatial analysis shows that municipalities (districts) in the Paris have the highest PPWS values, on the contrary, the peripheral municipalities in the outer suburbs have the lowest PPWS values and the results for the intermediary municipalities—in the inner suburbs—are contrasting. The numerical analysis demonstrates a strong correlation between the main parameters influencing the PPWS value; where a high value for the “roof area” means a high value for the “number of inhabitants” and a good mix of rainwater “use scenarios,” and vice‐versa. In conclusion, the planning and design of the municipality—building density, types of buildings, number of inhabitants, the city's vocation—are key factors in defining the level of PPWS made using rainwater harvesting.     

Part I. Identifying anthropogenic markers in surface waters influenced by treated effluents: a tool in potable water reuse

In potable water reuse, treated wastewater becomes part of the drinking water supply. An important question associated with this practice is whether or not the organic quality of the treated wastewater is chemically different from that of non-human impacted water. This question was addressed in a case study of indirect potable water reuse where the organic matrix of the South Platte River was analyzed upstream and downstream of the discharge of treated wastewater effluent using conventional water quality parameters combined with pyrolysis-GC/MS. Effluent-derived organic material (EfOM) was found to be more aliphatic and had higher organic nitrogen and halogen content compared to organic material derived from "natural" (non-anthropogenic) sources (NOM). Seasonal changes that resulted from the change in the contributions of aquatic and terrestrial sources were not observed in EfOM; but they were strongly observed in NOM under the control of natural processes. Using principal component and factor analyses, the pyrolysis fragments of phenol, alkyl-phenols, and acetic acid were identified as the seasonal indicators for the NOM set of samples. In contrast, benzaldehyde, benzonitrile, chlorobutanoic acid, furancarboxaldehyde, and methylfurancarboxaldehyde were identified as the indicators for wastewater inputs for the EfOM set of samples. Overall, the results from conventional water quality parameters and pyrolysis-GC/MS revealed that: (1) EfOM bears a chemical signature distinct from NOM and (2) under the conditions of this study, EfOM discharged to the South Platte River persisted and controlled organic quality at downstream points.     

Managing water demand by contract: a survey of conservation outsourcing in China

The research was to gain insight into the characteristics, driving forces and barriers, specifications, and other issues of water conservation outsourcing contracts (OSCs) in China. Our analysis is based on information obtained from a pre-coded questionnaire, an assessment of OSC documents, and project on-site visits and interviews. The result shows that both parties of the OSCs lack knowledge and experience in preparing contracts. All eight contract documents are underspecified, which is the key reason for the existing disputes found in all OSCs studied. Recommendations are provided by this research to improve China's OSCs in the future.     

End‐use analysis of household water by metering: the case study in Korea

The purpose of this study is to estimate the real water use for a person per day by analysing water use trend of respective metered data. To investigate the unit amount used and component ratio of residential water usage in households, 146 households nationwide were selected as ‘representative samples’, and each end‐use usage was monitored by actual metering from 2002 to 2006. From the results of analysing the acquired data, it was found that the unit amount used in a household was 165.8 litres per capita day (lpcd). Additionally, the unit amount used consisted of six end‐uses; toilet water was the greatest, at 25% (38.5 lpcd), laundry water represented 20% (30.8 lpcd), kitchen water was 19% (28.4 lpcd), bathtub water was 16% (24.7 lpcd), washbowl water was 10% (15.4 lpcd) and miscellaneous use of water represented 9% (13.5%). Comparing the unit amount used according to housing type, 141 lpcd was shown in the case of single houses, and 155 and 159 lpcd were derived in the cases of multi‐unit houses and apartments, respectively. Moreover, the proportions of the aged (50 and over) among the total number of members in single, multihouse and apartment houses were 68.2, 38.1 and 32.4%, respectively. In addition, comparing the amount used and the component ratio among United Kingdom, United States and Korea, the end‐use amount and component ratio in Korea are similar to those in the United States. The total amount of water use in the United Kingdom was less than that in both Korea and the United States.     

Nitrogen, land and water inputs in changing cattle farming systems.: A historical comparison for France, 19th-21st centuries

This paper provides an original account of the long-term regional metabolism in relation to the cattle rearing in western France starting by the precise formulation of animal diets at three key dates of the 19th, 20th and 21st centuries. We established links between the demand in fodder of the meat and dairy sectors and the necessary inputs of nitrogen, water and land as well as the land cover changes occurring on the affected local and remote cattle acreage. The average agricultural productivity for fodder supply is estimated at about 50 kg N/ha in the mid-19th, 54 kg N/ha in the early 20th and 150 kg N/ha at the turning of the 21st century. Jointly for the dairy and meat productions, the potential efficiency in the conversion of the vegetal into animal protein more than doubled over the studied period, passing from less than 9% in the 19th to 20% in the 21st century. The current cattle sector is sustained for about 25% by land situated beyond the regional frontiers and uses water at intensities that approach or exceed the availability of renewable water. The nitrogen pollution is expressed in terms of the Net Anthropogenic Nitrogen Inputs (NANI) and, by comparison to the N recovered in products, is used to define the N-Environmental Efficiency of the farming. We discuss the historical succession of the factors that contributed to the growth of the meat and milk production and make a comparison of the impacts and policy between the local and distant resources.