Roof rainwater harvesting systems for household water supply in Jordan

The largest environmental challenge that Jordan faces today is the scarcity of water. Current water use already exceeds renewable supply. Many methods have been suggested to increase the sources of water supply; one alternative source is rainwater harvesting. Rainfall harvesting from rural/urban catchments has not received large attention in Jordan. In the absence of run-off sewer systems in most Jordanian rural and urban areas, rainfall harvesting from roads, parking lots and rooftops can increase water supply for various domestic uses and help combat the chronic water shortages in the country. The objectives of this paper are to (1) evaluate the potential for potable water savings by using rainwater in residential sectors of the 12 Jordanian governorates; and (2) provide some suggestions and recommendations regarding the improvement of both quality and quantity of harvested rainwater. Results show that a maximum of 15.5 Mm(3)/y of rainwater can be collected from roofs of residential buildings provided that all surfaces are used and all rain falling on the surfaces is collected. This is equivalent to 5.6% of the total domestic water supply of the year 2005. The potential for water harvesting varies among the governorates, ranging from 0.023 x 10(6)m(3) for the Aqaba governorate to 6.45x10(6)m(3) for the Amman governorate. The potential for potable water savings was estimated for the 12 governorates, and it ranged from 0.27% to 0.7%. Analysis of samples of harvested rainwater from residential roofs indicated that the measured inorganic compounds generally matched the WHO standards for drinking water. On the other hand, fecal coliform, which is an important bacteriological parameter, exceeded the limits for drinking water.