Conselho Nacional de Desenvolvimento Científico e Tecnológico / This work shows a study about the system efficiency of rainwater s usage in the central region of Rio Grande do Sul and it aims to evaluate the utilization of not potable waters´ potential that come from impermeable surfaces. The hydrological potential was classified very good, considering pluvial sources (rainwater) from 30 regions' station, with historical series higher than 15 years. The activities to exploitation and its respectively demands were chosen, determining the efficiency of the system usage, with the use of different areas of captation and commercial volumes of rainwater tanks. The volumetric reliability was calculated in single-family house with the use of daily and monthly precipitation from the historic series of Santa Maria (code 02953034), volumes of 10, 12 and 20 m³ and areas of 70, 100, 150, 200 and 300 m². It was verified that the use of daily or monthly sources (datas) of precipitation conducted to nearest results. There are coincidences to minimum values, including in the dimension of the area s captation and the volume of storage. However, it was observed that to maximum reliability, the volume s results and the areas are bigger when monthly sources (datas) were used. In order to compare the sources, it was analyzed the efficiency applying volumes of water tanks determined by Kobiyama and Hansen Method (2002) to Cacequi´station (code 02954001). In this case, it was also determinated the captation s area that resulted in better volumetric reliability. The comparative analysis between the studied stations showed that there is a significant efficiency s development in function to the increase of the area of captation to the same volume of storage in comparison to a small variation of efficiency to the enlargement to the volume of a constant area. The methodology in this study offers an interconnected vision of the influence of the different constituents of the system usage, simulating the behavior of the system as a whole. The demands of single-family house with area of 70 m2 and water tanks of 500 L the minimum of efficiency found was 20% and the maximum was 28.33%. To multi-store building with area of 300 m² and 15000 L of reservoir s volume, the minimum was 10% and the maximum was 17.33%. In Gas Stations with 1000 m² of area and volume of 20000 L, the minimum volume was 40% and the maximum 58%. In beer s industry with area of 7000 m² and reservoir volume of 20000 L, the results showed minimum of 25% and maximum of 38.65¨%. The method presented makes possible the graphic visualization of the efficiency to be obtained in the usage systems to determine captation area, rainwater tanks volume and the implemented demands. It also allowed to verify the dimension to be projected in relation to captation s area and the volume of storage, since the demands has been determinated to reach and determine the intended efficiency. The equation s adjustment to the reservoir s sizing was obtained from a R2 coefficient adjustment of 0.9925 and from Nash coefficient of 0.9914. The criteria showed and discussed revealed adequate, resulting in efficiencies quite satisfactory to partial demands to not potable waters in the analyzed cities. / Este trabalho apresenta um estudo da eficiência do sistema de aproveitamento das águas pluviais na região central do Rio Grande do Sul e tem como objetivo geral avaliar o potencial de aproveitamento para fins não potáveis de águas provenientes de superfícies impermeáveis. O potencial hidrológico foi classificado considerando os dados pluviométricos de 30 estações da região, com séries históricas superiores a 15 anos e resultou Muito Bom . As atividades para aproveitamento e suas respectivas demandas foram escolhidas, determinando-se a eficiência do sistema de aproveitamento, com a utilização de diferentes áreas de captação e volumes comerciais de reservatórios. A confiabilidade volumétrica foi calculada em residência unifamiliar com a utilização de precipitações diárias e mensais da série histórica de Santa Maria (código 02953034), volumes de 10, 12 e 20 m³ e áreas de 70, 100, 150, 200 e 300 m². Foi verificado que o uso de dados diários ou mensais de precipitação conduziu a resultados próximos. Para valores mínimos há uma coincidência, inclusive, nas dimensões da área de captação e volume de armazenamento. Entretanto, para confiabilidade máxima observa-se que os resultados de volumes e áreas são maiores quando do uso de dados mensais. Por critérios comparativos procedeu-se, também, a análise da eficiência com o emprego de volumes de reservatório determinados pelo método de Kobiyama e Hansen (2002) para a estação de Cacequi (código 02954001). Neste caso, determinou-se também, as áreas de captação que resultavam em melhor confiabilidade volumétrica. A análise comparativa entre as estações estudadas demonstrou que existe um crescimento mais significativo da eficiência em função do aumento da área de captação para um mesmo volume de armazenamento em comparação a uma menor variação da eficiência para um aumento do volume a uma dada área constante. A metodologia proposta oferece uma visão interligada da influência dos diferentes constituintes do sistema de aproveitamento, simulando o comportamento deste como um todo. Para a demanda em residências unifamiliares com área de 70 m² e volume do reservatório de 500 L a eficiência mínima encontrada foi 20% e a máxima de 28,33%. Já para residências multifamiliares com área de 300 m² e volume de 15000 L a mínima foi de 10% e a máxima de 17,33%.. Nos postos de combustíveis com área de 1000 m² e volume de 20000 L o valor mínimo foi de 40% e o máximo de 58%. Em indústria de cerveja com área de 7000 m² e volume do reservatório de 200000 L os resultados demonstraram um mínimo de 25% e máximo de 38,65%. O método apresentado possibilita a visualização gráfica da eficiência a ser obtida nos sistemas de aproveitamento para determinada área de captação, volume de reservatório e demanda já implantada. Permite ainda, verificar as dimensões a serem projetadas em termos de área de captação e volume de armazenamento, conhecida a demanda, para que se consiga atingir uma determinada eficiência pretendida. O ajuste da equação para dimensionamento do reservatório foi obtido para um coeficiente de ajuste R2 de 0,9925 e Coeficiente de Nash de 0,9914. Os critérios apresentados e discutidos mostraram-se adequados resultando em eficiências consideravelmente satisfatórias ao atendimento parcial das demandas para fins não potáveis nos municípios analisados.

Vattenbesparing och alternativa lösningar för att tillgodose vattenbehovet har blivit mer aktuellt de senaste åren med torka. Regnvatteninsamling för hushållsanvändning används redan på många platser runtom i världen men är begränsad i Sverige idag. Syftet är att dels undersöka en lämplig dimensionering av ett system för regnvatteninsamling för hushåll i Jälåsa och att identifiera olika drivkrafter och hinder. Metoden i denna studie har varit dels massbalans- och effektivitetsberäkningar för att se hur mycket regnvatten som kan samlas in och dels intervjuer med två teknikleverantörer och fem kommuner för att utvärdera den juridiska, sociala och ekonomiska potentialen. Resultatet visade att tankstorlek på mellan 1000 och 4000 liter är rimligt för hushållsanvändning till toalett eller toalett och tvättmaskin och ger en effektivitet (procent av vattenbehovet som täcks av regnvatten) på mellan 83,6 % och 96,0 %. Vilken storlek som är mest lämplig beror på faktorer såsom vad regnvattnet används till, takyta, antal personer i hushållet och om first-flushbortledning används. Beräkningar visar att ungefär 19-29 % av den totala dricksvattenförbrukningen skulle kunna sparas i Järlåsa, vilket motsvarar ungefär 4 400 till 6 700 kubikmeter dricksvatten per år. Resultatet visar även att torrperioder då tanken är tom blir kortare med en större tankstorlek och det finns tydliga skillnader i volym vatten i tanken mellan olika nederbördsrika år. Enligt kommuner ansågs potentialen för regnvatteninsamling vara störst för bevattning i dagsläget men att de även var positivt inställda till annan användning såsom toalettspolning och tvättmaskin. Identifierade hinder var oro kring kontamination av dricksvatten, brist på ekonomisk lönsamhet till följd av låga dricksvattenpriser i Sverige och behov av förtydligande av krav och vilka risker som finns med regnvatteninsamling. Idag är potentialen och motivationen som störst för de som har dålig tillgång på vatten och en ökad miljömässig medvetenhet skulle kunna öka implementeringen av regnvatteninsamling i Sverige. Slutsatsen är att det finns potential för regnvatteninsamling men att det fortfarande krävs viss utveckling och mer kunskap om regnvatteninsamling under svenska förhållanden. / Water saving and alternative solutions to supply drinking water have become more important due to several consecutive droughts in recent years in Sweden. Rainwater harvesting for households is already being used in many places around the world but still has limited application in Sweden. The purpose with this study is to investigate a suitable sizing of a rainwater harvesting system in Järlåsa and to identify drivers and obstacles for implementation. The methods used in this study were firstly calculations based on mass balance and efficiency estimates and secondly interviews with two technology providers and five municipalities. The results showed that a tank size between 1000 and 4000 liters would be suitable for the purpose of supplying water for flushing toilets and for washing machines and the efficiency (percentage of water demand being met by rainwater) would be between 83,6% and 96,0%. What size tank is recommended depends on factors such as what rainwater is used for, roof area, number of people in household and whether first-flush is diverted. Results show that around 19-29%, around 4 400 to 6 700 cubic meters per year, of the total potable water consumption could be saved in Järlåsa every year using rainwater harvesting. The results also show that the dry periods, when the tank was empty, become shorter with a larger tank size and that there are distinct differences in the volume rainwater in the tank between years with varying precipitation. According to municipalities the potential was highest for irrigation purposes today but there was also potential for use in household for flushing toilets and supplying washing machines. The identified obstacles were concern regarding contamination of the drinking water supply, lack of economic profitability as a consequence of low water prices and the need for clarification of requirements and risks with rainwater harvesting. Today the potential and motivation is highest for those with an insufficient water supply and an increase in the environmental awareness could possibly enhance implementation further. The conclusion is that there is potential for rainwater harvesting but that there still is a need for some development and more knowledge regarding rainwater harvesting under Swedish conditions.