Download as DOCX, PDF, TXT or read online from Scribd
Download as docx, pdf, or txt
You are on page 1of 13
Rainwater Harvesting
Rainwater harvesting is collecting the run-off from a structure or other
impervious surface in order to store it for later use. Traditionally, this involves harvesting the rain from a roof. The rain will collect in gutters that channel the water into downspouts and then into some sort of storage vessel. Rainwater collection systems can be as simple as collecting rain in a rain barrel or as elaborate as harvesting rainwater into large cisterns to supply your entire household demand. The idea of rainwater harvesting usually conjures up images of an old farm cistern or thoughts of developing countries. The reality is that rainwater harvesting is becoming a viable alternative for supplying our households and businesses with water. It’s not just for the farm anymore! There are many countries such as Germany and Australia where rainwater harvesting is a norm. Due to the green building movement, you will be seeing rainwater harvesting systems become more popular here in America. The collection of rainwater is known by many names throughout the world. It ranges from rainwater collection to rainwater harvesting to rainwater catchment. In addition, terms such as roofwater collection or rooftop water collection is also used in other countries. We believe that rainwater harvesting is a viable technology in an urban setting. All that is necessary to take advantage of this resource is to capture the free water falling on your roof and direct it to a rainwater storage tank. By doing this, you can take control of your water supply and replace all or at least a substantial portion of your water needs. Rainwater harvesting systems can be configured to supply your whole house and/or your landscape needs. Need for Rainwater Harvesting Water is the reason why life exists on planet Earth, without it life is unimaginable. However, freshwater sources are becoming scarce with the passage of time. Reports of several global agencies including United Nations indicate that if the current situation of water does not change and preventive measures are not taken, then the world will start to run out of fresh water by 2050. Rainwater Harvesting is a sustainable process that helps in preserving rainwater for different purposes and for future needs as well. Rainwater Harvesting is a method of collecting and storing rainwater to be used for various purposes while it can be used in future as well. A large quantity of water is used for irrigation and there is an urgent need for proper water management in the irrigation sector. Over-irrigation through canals has led to water-logging in western Uttar Pradesh, Punjab, Haryana and Hirakud command area. Seepage along the canals can be checked by lining them. The overdraft by tube-wells has resulted in lowering of the water table in a number of villages in Haryana, Punjab and western Uttar Pradesh. In arid areas, wherever water has been brought for irrigation, saline and alkaline tracts have emerged, rendering the soil infertile. Wasteful use of water should be checked. Sprinkler irrigation and drip irrigation can play a crucial role in conserving scarce water resources in dry areas. Drip irrigation and sprinkles can save anywhere between 30 to 60 per cent of water. Only 0.5 per cent—nearly half of this in Maharashtra—is under drip irrigation and 0.7 per cent under sprinklers. There is large-scale pollution of water as a result of industrialization and urbanization. This trend has got to be checked. Although one-eighth of India is declared as flood-prone, there are several thousand villages in India which do not have potable drinking water. The basins should be treated as one unit for planning water utilization. Dry farming should be practised in dry areas. The experimentation under the National Watershed Development Program for Rainfed Agriculture is being carried on since 1986-87. There is a great demand of water in industries and the industrial sector offers great opportunities to conserve water. The economy in water- use in this sector will have two benefits. Firstly, the saved water may be used to meet the demand in other sectors. Secondly, the affluent thrown in the water bodies will be less. Rainwater harvesting is the most effective method of water conservation. It is used to collect and store rainwater for use by humans, animals, agriculture and industries. The rainwater in this process is collected at the surface before it is lost as surface runoff. The groundwater is then recharged artificially through the process. This is the most useful method for a developing country like India, where there is a huge gap in demand and supply of fresh water while also reducing the cost of transportation and treatment of water for use.
Rainwater Harvesting System
Rainwater harvesting systems can range in complexity, from systems that can be installed with minimal skills, to automated systems that require advanced setup and installation. The basic rainwater harvesting system is more of a plumbing job than a technical job, as all the outlets from the building's terrace are connected through a pipe to an underground tank that stores water. There are common components that are installed in such systems, such as pre-filters (see e.g. vortex filter), drains/gutters, storage containers, and depending on whether the system is pressurized, also pumps, and treatment devices such as UV lights, chlorination devices and post-filtration equipment. Systems are ideally sized to meet the water demand throughout the dry season since it must be big enough to support daily water consumption. Specifically, the rainfall capturing area such as a building roof must be large enough to maintain an adequate flow of water. The water storage tank size should be large enough to contain the captured water. For low- tech systems, many low-tech methods are used to capture rainwater: rooftop systems, surface water capture, and pumping the rainwater that has already soaked into the ground or captured in reservoirs and storing it in tanks (cisterns). Applications Of Rainwater Harvesting Domestic use Rooftop rainwater harvesting is used to provide drinking water, domestic water, water for livestock, water for small irrigation, and a way to replenish groundwater levels. Agriculture In regards to urban agriculture, rainwater harvesting in urban areas reduces the impact of runoff and flooding. The combination of urban ‘green’ rooftops with rainwater catchments have been found to reduce building temperatures by more than 1.3 degrees Celsius. Rainwater harvesting in conjunction with urban agriculture would be a viable way to help meet the United Nations Sustainable Development Goals for cleaner and sustainable cities, health and wellbeing, and food and water security (Sustainable Development Goal 6). The technology is available, however, it needs to be remodeled in order to use water more efficiently, especially in an urban setting. Kenya has already been successfully harvesting rainwater for toilets, laundry, and irrigation. Since the establishment of the country's 2016 Water Act, Kenya has prioritized the regulation of their agriculture industry. Additionally, areas in Australia use harvested rainwater for cooking and drinking. Studies done by Stout et al researching the feasibility in India found RWH was most beneficial used for small-scale irrigation, which provides income with the sales of produce, and overflow used for groundwater recharge. Industry Frankfurt Airport has the biggest rainwater harvesting system in Germany. The system helps save approximately 1 million cubic meters of water per year. The cost of the system was 1.5 million dm (US$63,000) in 1993. This system collects water from the roofs of the new terminal which has an area of 26,800 square meters. The water is collected in the basement of the airport in six tanks with a storage capacity of 100 cubic meters. The water is mainly used for toilet flushing, watering plants and cleaning the air conditioning system. Rainwater harvesting was adopted at The Velodrome – The London Olympic Park – in order to increase the sustainability of the facility. A 73% decrease in potable water demand by the park was estimated. Despite this, it was deemed that rainwater harvesting was a less efficient use of financial resources to increase sustainability than the park's blackwater recycling program. Advantages Reduced Water Bills Rainwater harvesting systems are cost-effective, provide high-quality water, lessens dependence on wells and are considerably easy to maintain since they are not utilized for drinking, cooking or other sensitive uses. The all-around expenditures used in setting up harvesting methods are much cheaper compared to other purifying or pumping means. The cost of recharge to the subsurface reservoir is also lower than the surface reservoirs. Ecological benefit Storing water underground is environment-friendly. The ecological benefits of rainwater harvesting are immense. It minimizes the impacts of flooding by funneling the off water into large tanks for recycling and helps reduce the load placed upon drainage systems. No land is wasted for storage purpose and no population displacement is implicated therefore, groundwater is not directly exposed to evaporation and pollution. Additionally, it helps minimize the possibility of rivers drying up. Reduces erosion and flooding around buildings It reduces soil erosion and flood hazards by collecting rainwater and reducing the flow of stormwater to prevent urban flooding. Most buildings that utilize rainwater harvesting systems have a built-in catchment area on top of the roof, which has a capacity of collecting large volumes of water in case of rainstorms. An adequate means for Irrigation purpose Harvesting rainwater allows the collection of large amounts of water and mitigates the effects of drought. Most rooftops provide the necessary platform for collecting water. Rainwater is mostly free from harmful chemicals, which makes it suitable for irrigation purposes. Reduces demand on Ground Water Another vital benefit is that it increases the productivity of aquifer resulting in the rise of groundwater levels and reduces the need for potable water. It is extremely essential, particularly in areas with low water levels. Disadvantages 1. Unpredictable Rainfall Rainfall is hard to predict, and sometimes little, or no rainfall can limit the supply of rainwater. It is not advisable to depend on rainwater alone for all your water needs in areas where there is limited rainfall. Rainwater harvesting is suitable in those areas that receive plenty of rainfall. If rain is unpredictable, the use of a rainwater harvesting system can be critical to capturing the rain when it does fall. 2. Initial High Cost Depending on the system’s size and technology level, a rainwater harvesting system may cost anywhere between $200 to $2000 and benefit from it cannot be derived until it is ready for use. Like solar panels, the cost can be recovered in 10-15 years, which again depends on the amount of rainfall and sophistication of the system. 3. Regular Maintenance Rainwater harvesting systems require regular maintenance as they may get prone to rodents, mosquitoes, algae growth, insects and lizards. They can become breeding grounds for many animals if they are not properly maintained. 4. Certain Roof Types may Seep Chemicals or Animal Droppings Certain types of roofs may seep chemicals, insects, dirt or animals droppings that can harm plants if it is used for watering the plants. 5. Storage Limits The collection and storage facilities may also impose some kind of restrictions as to how much rainwater you can use. During the heavy downpour, the collection systems may not be able to hold all rainwater, which ends in going to drains and rivers. Rainwater collected during the first rainy season is generally not needed by plants until the dry season though it can be used for other household purposes. However, once the catchment is full, it cannot take advantage of future rains. Methods 1. Surface runoff harvesting In this method, rainwater flows away as surface runoff and can be stored for future use. Surface water can be stored by diverting the flow of small creeks and streams into reservoirs on the surface or underground. It can provide water for farming, for cattle and also for general domestic use. Surface runoff harvesting is most suitable in urban areas. Rooftop rainwater/storm runoff can be harvested in urban areas through: • Recharge Pit • Recharge Trench • Tubewell • Recharge Well 2. Groundwater recharge Groundwater recharge is a hydrologic process where water moves downward from surface water to groundwater. Recharge is the primary method through which water enters an aquifer. The aquifer also serves as a distribution system. The surplus rainwater can then be used to recharge groundwater aquifer through artificial recharge techniques. Rainwater in rural areas can be harvested through: • Gully Plug • Contour Bund • Dugwell Recharge • Percolation Tank • Check Dam/Cement Plug/Nala Bund • Recharge Shaft Although rainwater harvesting measure is deemed to be a desirable concept since the last few years, it is rarely being implemented in rural India. Different regions of the country practiced a variety of rainwater harvesting and artificial recharge methods. Some ancient rainwater harvesting methods followed in India which includes Madakas, Ahar Pynes, Surangas, Taankas, etc. Importance 1. Rainwater harvesting or the collection of rainwater in a proper way, can be a permanent solution to the problem of water crisis in different parts of the world. This simple method can put forward a solution which will be workable in areas where there is sufficient rain but the groundwater supply is not sufficient on the one hand and on the other surface water resource is insufficient. This is particularly applicable in hilly areas where it can be utilized for human consumption, by animals and also for farming. In remote areas, where surface pollution is comparatively low, rainwater harvesting is ideal. 2. Although the earth is three-fourths water; very little of it is suitable for human consumption or agriculture. Rainfall is unpredictable and there is a constant shortage of water in countries which are agriculture dependent or generally drought prone. 3. A bad monsoon means low crop yield and shortage of food. Even animals suffer from scarcity of water. Africa and the Indian subcontinent face acute water crisis during the summer months. The farmers are the most affected because they do not get sufficient water for their fields. Rainwater harvesting therefore is an ideal solution for farmers who depend on monsoon for consistent water supply. 4. Unavailability of clean water compels the consumption of polluted water, giving rise to water-borne diseases and high rate of infant mortality. In recent studies it has been observed that in Lima (Peru) nearly 2 million people do not have access to any water supply and those who do have access get water supply which has a high possibility of being contaminated. It has been reported that the water crisis in some parts of Honduras is so severe that the municipal corporation of those areas cannot supply enough water even to those residents who have municipal water supply connection. This has been reported by Anna Kajumuto Tibaijuka, Under- secretary General, UNED UN-Habitat. 5. If rain water, which comes for free, can be collected and stored, instead of letting it run off, it could be an alternative to back up the main water supply especially during dry spells. Its importance will not be limited to an individual family but can be used by a community as well. Systematic rainwater harvesting can help in irrigation with minimum use of technology and is therefore cost effective. This simple method can help farmers to prevent their crops from drying due to lack of water. It also creates a sense of social responsibility and awareness about the environment. 6. The importance of rainwater harvesting lies in the fact that it can be stored for future use. Just as it can be used directly so also the stored water can be utilized to revitalize the ground level water and improve its quality. This also helps to raise the level of ground water which then can be easily accessible. When fed into the ground level wells and tube well are prevented from drying up. This increases soil fertility. Harvesting rainwater checks surface run off of water and reduces soil erosion. 7. In areas having sparse and irregular rainfall, scarcity of water is a persistent problem. It cannot be completely resolved but can be mitigated through rain water harvesting. Rainwater harvesting is an ideal solution to water problems in regions which receive inconsistent rainfall throughout the year. Conclusion Harvesting and collection of rainwater is an adequate strategy that can be used to address the problem of water crisis globally. The use of a rainwater harvesting system provides excellent merits for every community. This simple water conservation method can be a boost to an incredible solution in areas where there is enough rainfall but not enough supply of groundwater. It will not only provide the most sustainable and efficient means of water management but also unlock the vista of several other economic activities leading to the Empowerment of people at the grass- root level. For this, the Government should come out with an appropriate incentive structure and logistic assistance to make it a real success. Rainwater harvesting is something that thousands of families across the world should participate in rather than pinning hopes on the administration to fight water crisis. This water conservation method is a simple and effective process with numerous benefits that can be easily practiced in individual homes, apartments, parks and across the world. As we all know that charity begins at home, likewise, a contribution to society’s welfare has to be initiated from one’s home.
Rainwater Harvesting: Understanding the Basics of Rainwater Harvesting (Transform Your Home and Farm With Rainwater to Uncover Self-sufficiency Secrets)