Roof Rain Water Harvesting Essay Example | Topics and Well Written Essays - 2000 words

Roof Rain Water Harvesting - Essay Example They are also considered as a decentralized water supply units where ground water resource is becoming very scarce and the cost of the replacement of various components in the municipal supply systems are becoming very high. The entire system of rainwater harvesting starts with a siphonic roof drainage unit which could drain the water from the roof to an onsite storage tank. This water is filtered and is used for various applications either indoor or outdoor as discussed earlier. In addition to savings in the water costs it would also help to obtain the building permits very easily due to the importance given in the renewable energy systems. The car park area is a very limited space and hence the rational method would be sufficient to compute the runoff into the storm sewers. As the carpark could be expected to be covered the area of the drainage basin shall be taken as the roof area. And the volume of the water available shall be computed as the area of the car park roof multiplied by the depth of rainfall. This quantity is emptied into the storm drains placed on the ground using conveyer pipes whose cross section is decided based on the intensity of rainfall. The intensity values would be helpful to understand how quicker the rainfall reaches the roof. Thus the discharge from the roof is computed using rational formula by substituting appropriate values for intensity of rainfall, time of concentration and coefficient of runoff. Major components of rainwater harvesting unit. Irrespective of the type of rainwater harvesting unit the important components that are attached to a typical roof top units are as follows: Figure 1 Layout of rainwater harvesting system (CRIACC, 2008) (i) Collection systems: The collection region consists of various arrangements installed to collect water from the catchments. In the case of roof top unit, the catchment is referred to the roof top available for harvesting the rain water. The systems to convey water to the storage starts from the catchments. Thus the conveyance systems consists of series of gutters and down pipes that are necessary to direct the water from the roof top catchment to the desired location of storage. (ii) Vessels for storage: The tanks or holding vessel of estimated volume shall be provided for storing the water collected during the rains. The water in the storage units would be left unused until the time of lean season. (iii) Roof wash system: A small portion of initial part of the rains is diverted using cisterns for cleaning purpose and also to remove the debris. Thus volume of water of about 20 gallons is often used for this purpose which often improves the water quality. (iv) The water delivery system: This consists of series of network of pipes and other arrangements that are installed for proper delivery of water. If the water need to be lifted to higher elevation then separate pumps need to be installed to lift the water to higher elevation. Some time, if the water is used for irrigation purpose, then suitable arrangements need to be installed to facilitate the process. (v) Filtration: The process of removing any suspended debris or fine dust from the water referred as the filtration. For most of the situations the filtration unit