Potential for potable water savings by using rainwater: An analysis over 62 cities in southern Brazil

2006 ◽  
Vol 41 (2) ◽  
pp. 204-210 ◽  
Author(s):  
Enedir Ghisi ◽  
Andreza Montibeller ◽  
Richard W. Schmidt
2015 ◽  
Vol 16 (2) ◽  
pp. 533-541 ◽  
Author(s):  
André Castellani Lopes ◽  
Ricardo Forgiarini Rupp ◽  
Enedir Ghisi

The state of Santa Catarina, southern Brazil, has been suffering from water scarcity mainly over summer due to high potable water consumption and outdated water supply system. On the coast, several cities have their population doubled due to tourism during summer. In this context, this paper aims to evaluate the potential for potable water savings by using rainwater in the residential sector of 60 cities located in Santa Catarina state. Computer simulations using the Netuno computer programme were performed considering long-term daily rainfall time series for each city and typical characteristics of houses such as roof area, number of people per house, potable water demand and non-potable water demand (rainwater demand). In total, 2,700 simulations were performed. From the computer simulations, an ideal rainwater tank capacity and the corresponding potential for potable water savings for each case were obtained. Results showed average potable water savings ranging from 75 to 461 litres/day per house and rainwater tank capacities ranging from 1,000 to 16,000 litres. Despite the production of average outcomes using long-term daily rainfall data in cities with a high inter-annual variation of rainfall, results showed that the use of rainwater in houses may bring considerable potable water savings in Santa Catarina state and so could contribute to mitigating the potable water shortages.


Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 930
Author(s):  
Gustavo Rosa ◽  
Enedir Ghisi

This study aimed to evaluate the installation of a system that combines rainwater to wash clothes and greywater to flush toilets in a house located in Florianópolis, southern Brazil. The evaluation consisted of determining the potable water savings, performing a financial analysis, and verifying the possibility of using rainwater and reusing greywater according to the local legislation. The reduction in potable water consumption was determined by comparing the monthly water and sewage bill, before and after installing the system, combining rainwater and greywater. The financial analysis was performed considering the financial benefits, operational costs, costs for installing the system, and local water tariffs. After installing the system, there was a decrease of 38.0% in the monthly potable water consumption, which represents a decrease of 7.00 m3 in the monthly potable water consumption. The payback periods for the old and new water tariffs were equivalent to, respectively, ten years and seven months, and eight years and five months. Both rainwater and greywater had parameters with concentrations higher than the limits established by the legislation. Therefore, the rainwater had to go through a device for discarding the first flush and needed disinfection; and the greywater needed to go through a treatment process. The results indicated that the system combining rainwater and greywater shows significant potential for potable water savings, which can be a good alternative to the preservation of potable water resources. It is important to note that current studies on rainwater use and greywater reuse are mainly related to non-potable purposes, but it was shown herein that rainwater can be used for washing clothes.


Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2351 ◽  
Author(s):  
Cureau ◽  
Ghisi

This article aims to estimate the reduction of potable water consumption and sewage generation in the city of Joinville, southern Brazil. Four strategies were considered to promote potable water savings: replacement of conventional toilets with dual-flush ones, greywater reuse, rainwater harvesting, and the combination of these three strategies. Residential, public, and commercial sectors were assessed. The potential for potable water savings ranged from 1.7% to 50.5%, and the potential for sewage generation reduction ranged from 2.1% to 52.1%. The single-family residential sector was the most representative for water savings and sewage generation reduction. The public sector would be the least contributor to such reductions. It was found that in the city of Joinville, for low non-potable water demands, greywater reuse was the most viable strategy to save water. When non-potable demand is high and there is a large catchment area, it is recommended to install rainwater harvesting systems. It was concluded that there is a high potential for potable water savings and reduction of sewage generation if measures were adopted in Joinville, but it is necessary to evaluate which strategy is the most appropriate for each building.


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