Sizing of Domestic Rainwater Harvesting Systems Using Economic Performance Indicators to Support Water Supply Systems

Abstract

This paper presents a monitoring-based investigation of rainwater collection systems using economic performance indicators in a group of households with nonconventional end-uses for rainwater that are not traditionally associated with rainwater supply. The monitored data for five household rainwater tank systems were analysed in two stages. For the first stage, the data was empirically analysed to develop a method to predict effective roof catchment areas. For the second stage, the effective roof catchment areas, together with roof area connection percentages, were analysed against different types of water demands in individual households. The individual systems were investigated for yield capacities, costs and water security using a modified Roof Runoff Harvesting Systems average annual yield model based on daily water balance procedures. The Life Cycle Costing analysis of the systems using the model was based on the Capital Recovery Method by taking into consideration the capital costs as well as ongoing costs for maintenance, replacement and operation of the systems. The analysis established the optimal sizing requirements for the studied rainwater tanks and their corresponding roof area connectivity.

Assessing the Potential for Potable Water Savings in the Residential Sector of a City: A Case Study of Joinville City

“…In Philadelphia, USA, it was observed that the most common roof areas were in the range of 50-60 m 2 [12]. In New York, most houses had roof areas between 80-90 m 2 [12]. In this study, the average roof area of 57,946 houses was 101.6 m 2 .…”

“…Regarding the rest, the relative frequency percentage was between 0-5%. In Philadelphia, USA, it was observed that the most common roof areas were in the range of 50-60 m 2 [12]. In New York, most houses had roof areas between 80-90 m 2 [12].…”

“…Climate, as well as social and economic changes, has forced society to continually adapt to water shortages [6][7][8]. Various strategies have been developed and improved in the last decades to mitigate water shortage, such as rainwater harvesting [9][10][11][12], greywater use [13], and hybrid rainwater-greywater systems [14].…”

“…The viability of rainwater harvesting systems depends completely on the roof areas [23]. Regarding the roof area, these studies have been conducted considering: typical roof areas [12]; total roof area of buildings in a chosen region [16]; a specific roof area per person [20]. However, the estimated roof areas may not properly represent reality.…”

The Quality of Stored Rainwater for Washing Purposes

“…A typical RWH system consists of the concentration, collection, and storage of rainwater for use on site and reduction of drinking water consumption from centrally supplied sources. In urban areas rainwater can be collected from impervious surfaces such as roofs, terraces or courtyards [24]. Harvested water is stored in above or underground tanks with capacities designed according to water demand [6,25].…”