Conventional Rainwater Systems gather run-off rainwater for ecological running, domestic, and agricultural use. Rainwater systems can be drawn back to ancient civilizations who would collect water falling on their roofs in a process called rainwater harvesting. Of late, rainwater harvesting has improved in popularity as people begin searching for more workable buildings. However, a bulk of water systems today are still not worried about harvesting rainwater; instead, most water systems transport the rainwater to bodies of water through gutters, inlets, and storm sewers. Conventional rainwater systems divert rainwater into bodies of water in order to prevent flooding. Gutters, ditches, and other small scale water relocation devices are often called minor rainwater systems. The main resolution of these minor systems is to collect rainwater from the roofs of buildings and transport it to larger systems that can handle larger volumes of water. Gutters and downspouts are one example of minor rainwater systems larger rainwater systems are typically called major rainwater systems. Rainwater systems typically are used to both transport and filter large amounts of rainwater. Examples of major rainwater systems include storm sewers, water retention ponds, and water treatment plants. Occasionally, rainwater is treated before it is discharged. One of the simplest ways to treat rainwater is by using a water retention pond. The primary objective of a water retention pond is to reduce the peak rate of surface runoff like a water detention pond. The second aim of a water retention pond is to remove some of the pollution in the water. In addition to using retention ponds, rainwater could also be treated by diverting the water to a wastewater treatment plant where the rainwater would be combined with sanitary waste. Treating rainwater is a good way to promote sustainability because untreated water can contain hazardous chemicals like motor oil and pesticides that may harm the environment. Ancient civilizations have been using rainwater harvesting systems for thousands of years. There is evidence of rainwater harvesting in 2600 B.C in the ancient Harappa civilization. The Harappa’s used tanks to store rainwater; this water was then used for agricultural purposes.
Rainwater harvesting continues to be an important part of ancient society until wells and pipes allowed for water to be transported more effectively. Recently, rainwater harvesting has become more popular due to greater demand for clean water especially in India and other parts of Southeast Asia were clean water is not easily accessible.
Simple RWH system includes a catchment (1), delivery system (2), and storage reservoir Harvested rainwater that will be used for potable use must include some sort of a filtration system. The main source of rainwater contamination is the organic matter, inter solids, faecal decomposition from birds, and trace amounts of metals. Rainwater harvesting has many benefits both environmentally and economically. One of the biggest advantages of rainwater harvesting is that it is an easy way to save money on water bills. Simple rainwater harvesting systems without filtration or pumps have virtually no upkeep expenses and can be easily used for watering lawns or agriculture. Non potable harvested water can also be used for toilet flushing in large buildings, which accounts for 30% indoor water use. Using harvested rainwater improves sustainability because it reduces people’s dependence on water that is removed from aquatic ecosystems like lakes and rivers. Rainwater harvesting systems eliminate the electricity required to pump water from the water treatment.
Rainwater harvesting also reduces the amount of water runoff. Reducing the amount of runoff that enters storm sewers can reduce the chances of flooding and erosion after a big storm. In conventional roof drainage systems, the above ground pipework generally consists of vertical downpipes, connecting the gutter outlets to some form of underground drainage network, and offset pipes, used where the gutter overhang is significant. It should be noted that an offset pipe is defined as a pipe with an angle less than 10 degrees to the horizontal. The capacity of the system as a whole is usually dependent upon the capacity of the gutter outlets rather than the capacity of the vertical downpipes. The flow within vertical downpipes will normally be free surface, with BS EN 12056- 3:2000 specifying that downpipes run no more than 33% full; this effectively installs redundant capacity within the system. If the downpipes are sufficiently long (normally greater than 5 meters), annular flow conditions may occur. Similarly, the flow conditions within offset pipes will also normally be free surface, with BS EN 12056-3:2000 specifying that offsets run no more than 70% full; indicating the need to install all offsets at a gradient. The design of the pipework can either be undertaken utilising the design tables in BS EN 12056-3:2000, or by applying the Wyly-Eaton equation for vertical downpipes and the Colebrook-White equation for offset pipes.