Modelling of a roof runoff harvesting system: the use of rainwater for toilet flushing

Abstract

The water balance of a four-people family rainwater harvesting system was calculated in a case study. The experimental water saving efficiency (WSE) was calculated as 87%. A simple computer model was implemented to simulate the behaviour of the rainwater harvesting system. In general, the rainwater collector volumes predicted by the daily model had shown a good correlation with the experimental values. The difference between the experimental and the predicted values for the stored volume can be explained by the lack of maintenance of the system that can affect its performance. On the basis of a long-term simulation of 20-year rainfall data, the following parameters were calculated: rainfall, water demand, mains water, rainwater used, over-flow and WSE. The collection of rainwater from roofs, its storage and subsequent use for toilet flushing can save 42 m 3 of potable water per year for the studied system. The model was also used to find the optimal size of the tank for the single-family household: a storage capacity of approximately 5 m 3 was found to be appropriate. The storage capacity and tank size were distinguished. The importance to take into account the dead volume of the tank for the sizing was indeed highlighted. C. Vialle

Environmental analysis of a domestic rainwater harvesting system: A case study in France

“…Water physicochemical and microbiological quality was studied over one year (Vialle, 2011;Vialle et al, 2011aVialle et al, , 2013. The rainwater volumes collected, overflowed or used for flushing toilets were also available from a one-year monitoring campaign (Vialle, 2011;Vialle et al, 2011b). This period corresponds to a rainfall of about 766 mm distributed among 174 days and 40% of these rainy days presented precipitations inferior to 2 mm.…”

Decision support system for community managed rainwater harvesting: A case study in the salinity-prone coastal region of Bangladesh

“…Daily time series provide similar results to hourly time series, while monthly time series generate inaccurate results [ [63] , [64] , [65] ]. Different hydrological parameters like volumetric reliability or water-saving efficiency [ 51 , [66] , [67] , [68] , [69] ]; time-based reliability [ 41 , 52 , [70] , [71] , [72] , [73] ]; overflow ratio [ 18 ]; detention time [ 18 , 62 ]; water saving efficiency [ 74 , 75 ] are calculated to assess the performance and reliability of RWH system.…”

Investigation of application of storm runoff harvesting system using geographic information systems (GIS): a case study of the Arak watershed, Markazi (Iran)

“…The largest environmental challenge that Iran and humankind in the world face today is the scarcity of water (Vialle et al 2011(Vialle et al , 2012Zhang et al 2014). This phenomenon, especially in Iran, seems to be due to climatic conditions, such as aridity and abundance of high solar radiation and by population pressure.…”