Location: House in Dullu Awas, Nepal
Scale: Individual scale
Implementing organisation: Private owner
Average annual rainfall: 1343 mm
Total volume of rainwater harvested: Approx 2,315 kilo liters
Area: 112 sqaure meter (roof top)
Last Visited: November, 2014
The Rain water is collected from the rooftop and the rain water is then conveyed to the vertical conduits (70 mm dia) to the filtration and storage system. The rain water enters into the filter system through 3 pipes which are provided to the nearest location of vertical conduit system, respectively. The manual first flush mechanism is provided to avoid contaminated water of first spell of rainfall. After this basic filtration, water enters into the underground storage tank of 15000 liters of capacity.
The rain water directly fills up the underground tank, further the overflow of the water goes into the filtration system which was initially planned to filter out the water going into the recharge structure.
The filtration system consists of 60 cm thickness of sand filled by 20 cm thickness of gravel with free board of further 20 cm. The surface dimensions of the filtration tank are 60 cm by 90 cm. The rain water after passing through the filtration enters into the well.
The initial intension for the construction of well was to use it as a recharge structure for ground water recharge, but due to the presence of non-permeable soil (black cotton) up to 22’-25’ level below the earth, the well could not be used for recharge but only for storage. The service well thus naturally formed is 22 feet deep with 42 inches diameter.
The potable water demand of the house and the school is 700 liters per day (drinking, cooking, bathing and washing) for which water is extracted from the underground storage tank in rainy days and in non-rainy days water is extracted from the service well. The system works on the water balance principal to fulfill the present water demand.
All the raw water is pumped to the roof holding tank of 2000 liters. The water from overhead tank goes to the bio sand filter for further treatment of household purposes.
Bio sand filter is the filtration device which cleans the water with the help of bio layer. The filtration rate of the filter is 1 liter/min which fills up the next tank of 1000 liters from where the water is used for drinking and cooking purposes.