Rainwater Collection and Usage - Essay Example

? Rainwater Collection Rainwater Collection Over 10billion of sewage is produced every day in England and Wales (including rainwater waste). This wastage should be prevented. Rainwater Harvesting This wastage can be prevented through a range of rainwater collection systems which ensure rainwater is recycled for reuse in homes and in institutions. To begin with, rainwater harvesting is a suitable system used to collect rainwater waste. Rainwater harvesting refers to the collection and storage of rainwater before it reaches the land surface. In this system, rainwater is collected on roofs of houses and institutions by simple construction, which uses inexpensive and readily available materials such as gutters and pipes. Moreover, the running costs are quite minimal. Areas best suited for this rainwater collection system are areas with no access to water resources, and areas that receive at least 200mm of rainfall per annum as this system’s effectiveness is pegged on the intensity of rainfall received. Rainwater harvesting systems channel rainwater from the roofs into storage tanks, either placed on the land or underground, through a variety of pipes and gutters. These pipes and gutters should be strong enough to accommodate large amounts of rainwater experienced during the rainy seasons and withstand the windy conditions peculiar to heavy storms (Gould and Nissen 2000, p. 35). The storage tanks, on the other hand, must always be covered to avoid mosquito infestation and contamination from dust, bird droppings and other contaminants. A property owner may choose to use a backup valve like an aqua saver, which automatically switches from rainwater tanks to mains supply whenever available, hence saving the property owner from the hustle of having to manually switch these valves. Rainwater collected through this system can be used in irrigation and washing clothes. However, we note that rainwater harvested from roofs may require treatment as it may be polluted by dust and dirt build on the roof. Moreover, areas accustomed to coal burning and large bird populations may produce roof rainwater contaminated by pollutants such as mercury. Residents in these areas may choose to use the water to flush toilets. It is advisable to allow the first flush of rainwater runoff as it clears the roof of any contaminants present. However, once treated, the water may become suitable for human and livestock drinking. Storm Water Harvesting Another system used in the collection of rainwater waste is storm water harvesting. This refers to the collection, treatment and storage of rainwater that has run off on the earth surface, or on surfaces specifically designed for this purpose. This system not only harvests run off rain water from drains, roads, parks or playing fields but may also collect snow that melts into storm water systems. The surface run off may be channeled into surface waterways or into water filtration systems tasked with filtering and treating the rainwater before it is stored ready for use. Moreover, surface run off may be filtered by using rain gardens. These are planted depressions that allow water infiltration by accumulating rainwater on the surface, filtering off any pollutants before the water is absorbed into the ground. Once absorbed, the water is channeled into storage tanks via pipes. Swales may, however, be used in place of rain gardens (Gould and Nissen 2000, p. 97). These are low tracts of land, usually marshy, that filter off pollutants from surface run off and improve infiltration. This system of collecting rain water is essential in the collection of water used for irrigation, flushing toilets and even drinking once the water is treated. It is also useful as it collects excessive runoff during heavy storms, which would otherwise lead to expulsion of raw sewage from outfalls when treatment plant capacities cannot handle the combined flow. The main challenge in this system is the removal of pollutants by use of retention ponds this problem is adequately solved. Steeper slopes may be constructed on the rainwater pathways in order to increase the flow of surface runoff, but these slopes have to be monitored to deter occurrence of soil erosion. However, these measures do not always guarantee that rainwater will not be absorbed into the ground, hence the need to construct water wells. Water Wells Water wells are structures created in the ground by either digging or drilling to access the water beds also referred to as aquifers. Water wells are useful in the collection of rainwater that has already infiltrated into the ground and has reached the aquifer. Water from these wells is drawn using submersible pumps that can be operated both manually and electrically. Through the process of infiltration, solid pollutants are filtered out, but well water may be contaminated by minerals found in soil, resulting in the formation of hard water (Gould and Nissen 2000, p. 115). This hard water may be used in irrigation, flushing toilets or washing cars. Treatment is, however, necessary to make this water fit for drinking and cooking. Water wells are connected to pumps that periodically pump water into the homes for the various uses. This design ensures a sustainable water supply and has minimal running costs. Various municipal councils have different policies on well location in home grounds to prevent the occurrence of accidents by people falling into them. Such regulations include: water wells should be built in pump houses and must always be covered to prevent contamination. However, this does not always guarantee high quality water standards as sewage systems sometimes percolate down from the ground surface through the top layers into the aquifers. This contamination may be prevented by ensuring wells is accessible for routine maintenance, monitoring and cleaning. Water wells should be constructed from high quality materials, both bricks and steel, to avoid collapsing and causing damage. Rain Directors In addition to these systems, rainwater can also be collected through rain directors. These are rainwater collection and management design which directs the flow of rainwater to toilets, washing machines, gardens and other avenues as needed. This system uses a header tank, placed on the roof top of a house, a pump and a programmable control valve. This valve controls the amount of water that goes into the various household utilities such as toilets. The system has a number of advantages, which make it suitable for household usage. For instance, the header tank is controlled by electronic sensors that operate the valves through the programmable control panel. This results in a constant pressure of water as needed in either the toilet or tap. In addition, this system collects rain water before it gets into contact with any contaminated surface; thus, the water does not require any treatment as it is already fit for consumption. Moreover, this system is placed on the roof, so there is no possibility of creating excessive noise in the house while it is running. The design assures one of a reliable water supply even in the event of power cuts as it is gravity oriented thus always functioning. Another significant advantage is that the header tank only refills once empty, thus minimizing electricity consumption and wear and tear on the pipes and pumps while pumping. In addition, this design is highly reliable as it automates the flush option when the owner is not around. This means that the header tank automatically empties to avoid water from going stale which could lead to serious health complications when consumed. Moreover, the header tank is always in cycling motion, which improves the quality of water released, and lastly, this design abides by the UK building regulations stating that rain water and mains water should never mix (Gould and Nissen 2000, p. 132). This is because the system’s header tank has an air gap that prevents the two water sources from getting mixed up. However, we note that this system is not easily available in the market as only a few manufacturers make the units. Soil Compaction Soil compaction is yet another design used in the collection of rainwater. This is the process of smoothening soil by applying pressure on it to dislodge any air present in the soil. This process can be done through either physical or chemical means. Physical means require the use of rollers and graders to clear, shape and compact the soil in catchment areas. Catchment areas are defined as land areas specifically apportioned to drain rainwater into other water bodies. Bench terraces are created along an inclination to reduce soil erosion and improve surface runoff; this could also be achieved through planting of grass along the edges. The terraces are separated by sloping collectors while uniform distribution of flow is managed through field strips as sheet flow. Excessive flow, however, is channeled into collectors on a lower level and stored for future use. Soil compaction results in soil impermeability being enhanced thereby leading to accumulation of rainwater on the surface. Chemical process of soil compaction, on the other hand, involves the use of chemical products such as sodium which when applied to the soil significantly reduces soil permeability. Aqueous solutions, which are silicone-water repellent based, could also be used in chemical compaction. Although this system is widely used, it can result to a reduction in soil permeability through the use of chemical applications thereby leading to soil erosion. This system is also quite expensive as it is both labour and financially intensive. In addition to this, use of sodium based chemicals results in an increased concentration of salt in the water collected, thus making it unsuitable for drinking and irrigation (Gould and Nissen. 2000, p. 85). Soil compaction forms the basis for construction of other water collection designs and systems such as dams, ponds and pans. Dam Construction Rainwater collection may also be done through the construction of dams. These are water reservoirs built across streams or in areas that experience high surface runoffs. Simple earth dams can be constructed in areas that have impervious foundations such as clay subsoil. A gentle slope is also necessary to increase the flow of rainwater into the reservoir. It is recommended to use narrow valleys to form dams as they act as natural walls and increase the height of the dam and reduces its width resulting in more rainwater collection and water evaporation is minimized. For effective, uniform construction, one should enhance the walls by using soils containing high concentrations of clay, also ensure that the correct quantities are used to avoid development of cracks on the walls of the dam. The topsoil should always be removed as it may contain organic matter that prevents proper compaction and may, therefore, provide water seepage channels. A stone mattress should be laid on the slope and tied down using wires anchored to posts (Gould and Nissen. 2000, p. 23). This will filter out any solid contaminants present in the runoff rainwater. Moreover, strong grass should be planted along the banks of the dam to avoid soil erosion. Dam construction should only be done during the dry season in order to provide the materials ample time to compact. On the other hand, one must also make a provision for settlement because the weight of the dam increases through increased water levels hence; forcing out air and water from different voids. Once water has been collected in the reservoir, gravity outlets can be used in retrieving water needed for different uses. These gravity outlets are constructed using screened inlets on the bed of the reservoir, and pipes found in trenches below the dam. Rainwater collected in dams is useful in the generation of hydroelectric power, by running the water through gravity propelled turbines once the water is released from the reservoir (Gould and Nissen. 2000, p. 15). Moreover, this water can be used in irrigation, and once treated, can be used as drinking water for both human beings and livestock. Dams are also useful in fish breeding and husbandry, also produce beautiful scenery that is a key source of tourist attraction. However, we note a few shortcomings in the use of dams in rainwater collection. For instance, even when the highest standard construction materials are used and the soil is well compacted, water seepage is a common occurrence in dams. This may result in the weakening of the dam and ultimately loss of the collected rainwater. Moreover, this system of collecting rainwater is highly technical and may not be suitable for regular home use as it requires both large areas of land, and technical expertise. In addition, municipalities often choose to evict residents living on lands allocated to the construction of dams, creating a squatter problem. The UK regulations for dam construction require that one consult a relevant technical engineer to design and supervise the construction of dams. In addition, regular maintenance is required to check the dam and spillway condition and provide for necessary repair work. Pan Construction Pans are depressions on the earth surface, created for the purpose of collecting and storing rainwater. They are essentially ponds, however, can be bigger. They are usually between two to four meters in depth and are dug either by hands or use of machinery. Their length varies depending on the area allocation and the purpose of construction. A pan is constructed on an impermeable surface and may be lined by the use of clay-based soils. They are constructed by digging into the earth’s surface to form a depression, preferably on a flat area to create an even surface for rainwater collection and storage (Gould and Nissen 2000, p. 36). Clay-based soils may be used to enhance the walls, which should slope at an angle to allow for rainwater drainage. In addition, the pan banks should be lined with sandy soil and gravel held in place by use of wires. This sand and gravel is essential in sieving out any large contaminants before the rainwater runoff flows into the pan. Strong glass should also be planted on the banks to prevent soil erosion. It is recommended to construct pans on rainwater pathways or close to streams so as to collect any rainwater surface runoff. It is also key to construct pans in areas that receive heavy rains during one season, and none during another as pans provide a suitable system of collecting, and storing water for use during dry seasons (Gould and Nissen 2000, p. 25). Rain water collected in pans is best suited for use in irrigation and as drinking water for livestock. However, livestock may contaminate this water through their droppings; thus, it may become unsuitable for their consumption. Further contamination is possible through dust and pollen accumulation on the water surface as pans are not covered. Moreover, the rate of loss of rainwater through evaporation is high in this system of rainwater collection. However, in some municipalities, underground pipes are used to channel water collected on the pans into underground tanks or those placed on the ground. Water Tower Construction A water tower is an artificial water collection and storage facility constructed to high heights that encourage pressurization for efficient water distribution. These systems’ exteriors are constructed from steel and reinforced concrete, while the interiors are made from wood and bricks. However, to avoid contamination of the water in these systems through contact with the materials used, the interior is lined with fiberglass. Water towers may be used in the collection of rainwater that has already infiltrated the earth surface, when or before it reaches the aquifer level. This water is pumped through pipes that are erected in the ground, and channel the rainwater into filtration and treatment plants where all contaminants and pollutants are removed and the water is disinfected before being pumped into the water tower. These pipes should be sizeable and strong enough to contain the large amounts of water passing through them at extremely high pressure. The pressure released when the rainwater is pumped into the water tower is enough to make it rise to the reservoir located at the top of the water tower (Gould and Nissen 2000, p. 78). This pressure is referred to as hydraulic pressure and it is responsible for pumping water into the supply systems for homes, institutions and organizations. For instance, 20 centimeters of water elevation results in the release of 1 kilopascal of pressure. The reservoirs are usually cylindrically or spherically shaped according to the water tower design. Water towers are necessary in pumping up water supplies in hilly areas as the gravity flow in these areas results in lowered water pressure when using other systems. Water towers are a significant source of drinking water for both human and livestock. The rainwater is treated before being pumped into the system, so no further treatment is needed before consumption. The water can also be used in irrigation and other household utilities such as flushing toilets and use in washing clothes. Moreover, we note that most of the water towers were constructed during the Industrial Revolution and are considered monuments and architectural landmarks in some areas, for instance, the water tower of Lake Wales (Gould and Nissen 2000, p. 65). The water towers constructed during this period are outdated and may be ineffective in the distribution of consistent water supplies. Moreover, if the system is not sufficiently pressurized, it may result in water supply not reaching upper floors of buildings or insufficient flow or spray in taps. This negative pressure may also result in shallow underground and surface water being pulled into the water tower, thereby contaminating any water present in the system. In addition, the construction of these systems is expensive and requires intense labour, so may only be appropriate in government-funded projects. The operational costs are also high; from the use of pumps and heavy duty underground pipes that are subject to constant wear and tear. In addition, wireless sensor networks used in monitoring water levels, in these systems, are quite expensive. In conclusion, we note that collected rainwater may be used to boost city’s mains supplies. The rainwater collection systems are suitable as water is collected at the point of consumption; therefore, no transportation required. However, rainwater collection is determined by the prevailing weather conditions, therefore, no assurance of a constant supply. Reference Gould, J. and Nissen, E.P. 2000, Rainwater Catchment Systems. Intermediate Technology Publications, London. Read More