Grey Water and Rain Water as Alternative Sources of Flush Water and Irrigational Water in and around Households: A Case Study from Istanbul Atakoy District

Grey water and rain water are two options as alternative sources to alleviate water stress/scarcity across the world. This paper aims to investigate possible use of reclaimed grey water and harvested rain water from on-site premises as sources of flush water and irrigational water in and around households in the popular settlement district Atakoy of the water-stressed Turkish megacity Istanbul. Calculations using demographic and meteorological data along with an analysis of current municipal plans reveal that the rain water potential is 544 434 and grey water potential 2 070 662 (total)/880 032 (light grey water) m3/year in Atakoy. This indicates that 78% of 3 347 669 m3/year demand for flushes and irrigation of the entire green areas of privately-owned housing complexes may be covered by rain water and grey water in the area. While the entire flush water demand may be covered by light grey water only, 79% of flush water may be supplied if rain water is used. 98% of irrigational demand may be provided using both light grey water and rain water. The results show that considerable water savings may be achieved through the use of grey water/rain water which will aid sustainability.