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Assignment 2


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Assignment 2

  1. 1. HES 3112 –Water Resource Engineering 2011The Use of Rainwater Tanks to Supplement Water Supplies: Urban Water Issue Assignment Sharifah Nur Azureen Binti Wan Osmani (4224698) Tang Sieu Wei (4239547) tanks to supplement water supplies is an innovative technology where it can directlybenefits our state by reducing demand on water supply, save money, save energy and so onThere are a lot of advantages and as well as disadvantages in implement this method. The userainwater tanks to supplement water supplies are suitable to implement a sustainable water usagepractice in Malaysia.KEYWORDRainwater Tanks; Sustainable; Water Supplies; Rainfall; Sarawak; Rainwater HarvestingSystemINTRODUCTIONMalaysia has one of the highest rainfalls in the world at an annual average close to 3,000mm forwest Malaysia and 4,500mm for Sabah and Sarawak. However, this does not mean that thecountry has unlimited access to supplies clean water. The challenge now is for the water industryin Malaysia to overcome the paradox which more flooding occurs and irregular supply of waterfor consumer. A rainwater tank is a water tank which is used to collect and store rain waterrunoff, typically from rooftops goes through the rain gutters. Rainwater tanks are devices forcollecting and maintaining harvested rain. Rainwater harvesting has thus regained its importanceas a valuable alternative or supplementary water resource, along with more conventional watersupply technologies. Rainwater tanks are installed to make use of rain water for later use, reducemains water use for economics or environmental reasons, and aid self-sufficiency. The capacityof a harvesting system depends on the amount of rainfall, size of collection area, storagecapacity, and the household level of demand for water.Sharifah Nur AzureenTang Sieu Wei 1
  2. 2. HES 3112 –Water Resource Engineering 2011METHODS AND DISCUSSION(1.0)Review of the selected topicsThere are many ways to implement a sustainable water usage practice in Malaysia and one ofthem are the use of rainwater tanks to supplement water supplies. The reason we choose thistopic as urban water issue assignment is because Malaysia is one of the country that receivedhighest rainfalls amount of rainwater in the world that is annual average close to 3000mm forwest Malaysia and 4500mm for Sabah and Sarawak. This fact shows that Malaysia is suitable forthe rainfall harvesting technology to achieve a sustainable water usage practice.Besides, among all the other topics available, we think that this topic is the best to implement asustainable water usage practice in Malaysia because this is a simple practical method tosupplement water supplies whereas every house will be able to do this by themselves andpractice this method in saving water and one step ahead to achieve the awareness of Malaysian tobe sustainable in usage of water.(2.0)BenefitsRainwater acts as sustainable water supply option where rainwater can be utilized alone ortogether with other supply sources in residential, commercial and industrial projects where purewater is desired. Rainwater collected by rainwater tanks is suitable to use when there is auniform rainfall pattern in the area and even though a few days without rain, we still have areliable alternative water source nearby. Stored water can be used when the dry seasonhappening, when the groundwater is limited and contaminated, electricity and water prices arerising, when storms and disaster strike and for bushfire prevention purposes.Rainwater can be used throughout the year for all domestic purposes. For example, rainwater isused for gardening, drinking, washing car, and other. The available water should be wellmanaged and make sure that have enough storage capacity to bridge the dry period or wheregood quality water supplies are limited.Besides that, rainwater storage can be provided for bushfire prevention purposes. One of thebenefits is to access the mains water to encourage the conservation of water. Installing arainwater tank will reduce the average household bill significantly. Rainwater tanks are the bestsolution to the water restrictions during the current times of drought. In addition, in rural areas,rainwater is usually unpolluted before reaching the ground. It means that the rainwater fromwell-maintained roof catchments is most commonly safe for drinking. The rainwater are alsoideal for consumers that must restrict salt or chlorine intake because most of the tap water arealready mix the chlorine inside the water and this might not be good for the consumer.2 The Use of Rainwater Tanks to Supplement Water Supplies: Urban Water Issue Assignment
  3. 3. HES 3112 –Water Resource Engineering 2011(3.0) AdvantagesRainwater harvesting is a popular household option as the water source is close by, convenientand requires a minimum of energy to collect it. The users can maintain and control the householdsystems without the need to rely on the other members of the community. Operation andmaintenance of a household catchment system are solely by the tank owner’s family at anytimes. As such, this is a good alternative to poor maintenance and monitoring of a centralizedpiped water supply, this is the advantages that use of rainwater tanks to supplement watersupplies. Rainwater harvesting systems have been implemented successfully since almost allroofing materials is suitable for collecting rainwater.Rainwater harvesting is a simple low-cost technique that requires minimum specific expertiseand offers many benefits. The rainwater tanks built is no demands on public funds and can savethe cost. It can provide an important source in some places that relatively high rainfall spreadthroughout the year. Water supplies from rainwater tank are more convenient than water whichneeds to be carried. Collected rainwater can supplement other water sources when they becomescarce or are of low quality. It also provides a good alternative and replacement in times ofdrought or when the water table drops and wells go dry.Besides that, rainwater tanks can be found in all the great civilizations nowadays. Theconstruction of rainwater tanks can be very simple and local people can easily be trained to buildby themselves. It can reduce costs and encourages more participation, ownership andsustainability at community levels. One 20-litre container of clean rainwater collected from theroof can save a walk of many kilometers to the nearest clean water resources. Besides smallcontainers, large sub-surface and surface tanks also can be used for collecting larger amounts ofrainwater.The use of rainwater from water tanks is a useful alternative when many piped water supplysystems fail to increased need for water results in lower groundwater tables and depletedreservoirs. The availability of water from sources such as lakes, rivers and shallow groundwatercan fluctuate strongly. Collecting and storing rainwater can provide water for domestic use inperiods of water storage. Rainwater can be used for multiple purposes such as watering gardens,washing cars, flushing toilets, agriculture, and in washing machines. It also can be used fordrinking especially when other water supplies are unavailable, expensive or poor quality, andthat safety measurement is taken that the water is not contaminated or the water is periodicallyfiltered. Rainwater may also provide a solution when the water quantity is low during the dryseason in rivers or other surface water resources.One of the advantages of collecting and storing rainwater it is to improves the accessibility andconvenience of water supplies and has a positive impact on health. So, rainwater is generally ofgood quality and better than other available or traditional sources. Other advantages of userainwater tanks to supplement water supplies are low environment impact. Rainwater is arenewable resources and no damage to the environment. Rainwater is also not affected by localgeology or topography. Rainwater collection always provides an alternative wherever rain falls.Sharifah Nur AzureenTang Sieu Wei 3
  4. 4. HES 3112 –Water Resource Engineering 2011(4.0) DisadvantagesSome of the disadvantages of using rainwater tanks to supplement water supplies are high initialinvestment cost, regular maintenance, storage capacity limits the supply, insecure water quality,uncertain climate, and some other factors.The high initial investment cost is one of the disadvantages of using rainwater tanks as anadditional water supply because the cost of constructing the rainfall harvesting system is highand no profit is obtained until the system is complete and can be used or the cost of the tank andassociated accessories can be high compared to the cost of mains water actually saved. Thepayback period is the length of time required to recover the cost of an investment and this isdepend on the size of tank, the volume it can cater, the total rainfall collected, the costing, theassumption of usage daily and so on. After all the assumption and calculation had beendetermined, then the payback period is known. If the payback period of the investment is in longtime, then the adjustment need to be made and we can say that the system is more expensive thanusing the main water stream.Next, the water used for harvesting is full of pollutants which can lead to health issues and thispolluted environment will result in increasing amount of nitrates and fluorides in the water andbacteriological contamination levels will rise in water. The contaminations of bacteriologicallevels rise such that the water inside the tank is exposed to the sunlight which can stimulate algaegrowth. Plastic tank for example may allow light to penetrate in and to avoid this, the plasticshould be kept out of the sun or painted with dark color. Besides the contamination ofbacteriological, the need to prevent insect vectors from breeding inside the tank is crucial. Byproviding water tanks without any care for prevention from insect breeding can cause problemsthan it can be settle, for example, an area where the malaria might present is very dangerous,safety and care should be taken to prevent this situation from happen. The precautions that canbe take is all the tanks should be sealed to prevent the insect from entering and breeding insidethe water tank. For more safety, the mosquito proof screen can be fitted to the opening of thetanks.Rainwater can also be used for drinking and cooking but there are some highest possiblestandards are met. However, rainwater does not meet the World Health Organization (WHO)water quality guidelines but this does not mean that water is not safe to be drink. Gould andNissen-Peterson (1999), in their book, point out that the Australian government have given theall clear for the consumption of rainwater ‘provided the rainwater is clear, has little taste orsmell, and is from a well-maintained system.’ But as we know, the microbial quality of watercollected in tanks is not as good as the urban supplies and for a limited area that has a heavytraffic and the industrial area, the chemical released may affect the chemical quality of rainwaterand this is not good for health especially the young one. However, there are somerecommendation and aspect that we need to consider when one person want to make rainwater asdrinking water supplies, we should boil the water to 100 degree Celsius to make sure the harmfulbacteria do not present anymore. Next, adding chlorine to the rainwater in a right quantity willdisinfect the water.4 The Use of Rainwater Tanks to Supplement Water Supplies: Urban Water Issue Assignment
  5. 5. HES 3112 –Water Resource Engineering 2011Moreover, the limited space is one of the disadvantages for using rainwater tank to supplementwater supplies in daily life. Adoption of this technology requires a high cost and space areawhich making it less attractive to some governmental agencies to use this technology andbecome sustainable. This are also the reason many people just used the tap water instead ofrainwater because they do not have to provide a space for the rainwater tank. However this willnot be a problem to a individual or a residents area to use this technology because each houseonly require small amount of water compare to the governmental agencies and this does notinclude for drinking but only for washing, car wash, gardening, and so on. Generally, the biggerthe catchment area, the bigger space required and the larger amount of rainwater can becollected.Next, the regular maintenance is required when installing the rainwater harvesting system for thegood flow of the water from the catchment area then through the pipe until it reached the tank.Some of the debris may block the flow of rainwater to the tank and this may affect the amount ofwater collected and the hygiene if no maintenance is done. The water from water tap is readilyavailable in any hour and we as a consumer do not have to do a regular maintenance for thewater and this can save many times and save budget. The maintenance is not only cleaning thedebris periodically but it is also required the maintenance in the material used where some of thematerials may worn out in time and this also need a cost to maintain it in a good condition.Even though the regular maintenance is often and causing a lot in cash, the payback period canbe achieved in a short period of time, hence, this method is not actually a bad idea at all formaking the rainwater tank as the supplement for the water supply.The other disadvantages of using rainwater as the supplement water supply is the inconsistencyin climate, even though Malaysia received a huge number of rainfall amounts, it does not meanthat the rainfalls amount is the same everyday and there will be rain daily. From the observationobtained from Malaysia Metrological Department, the records for the monthly rainfall amountare different for all the states and division, for example for December 2010 and January 2011,the rainfall amount received in Kuching is 350mm (December) and 700mm (January); figure 1and 2. As we all know, the La Nina phenomenon that Is still active in January had causing mostarea in Peninsular, Sabah and Sarawak were still experiencing wet weather and received totalrainfall from average to very much above the monthly average. Whereas for December, theNortheast monsoon were still in active phase of this season lasts from November toJanuary and during this season period, the east coast of peninsula, the coast of Sarawak andeastern coast of Sabah would experiencing a few comprehensive heavy rain that go continuouslyas long as three days as results from the surge monsoon. However, for Sarawak specifically forKuching the rainfall amount are in normal distribution. From this fact, obviously, we can see thatthe inconsistency of rainfall for every month which can result an insufficient amount of waterwhen the rainfall amount per month is small.Lastly, there are also other disadvantage such as the rainwater tank may be dangerous to childrenwho play around it and the rainwater harvesting system are often not part of the building codeand lack clear guidelines for users or developers to follows and others.CONCLUSIONSharifah Nur AzureenTang Sieu Wei 5
  6. 6. HES 3112 –Water Resource Engineering 2011In conclusion, the usage of rainwater tanks to supplement water supplies is the best choice toimplement a sustainable water usage in practice in Malaysia. The rainwater acts as the alternativewater supply for the daily usage such as domestic purposes, emergency purpose and even for thecommercial purposes. This method is convenient, cost-efficient for small area covered andrequires a minimum of energy to collect the rainwater. This method is also suitable for the ruralarea where the access of clean water may be insufficient and it is an easy installed system. Ontop of all, rainwater tank to supplement water supplies is a suitable method to implement asustainable water usage practice for Malaysian.REFERENCES6 The Use of Rainwater Tanks to Supplement Water Supplies: Urban Water Issue Assignment
  7. 7. HES 3112 –Water Resource Engineering 2011Agua (2010), Agua solution : Fundamentals of rainwater harvesting,, viewed on 1 May 2011Anonymous (2009), Level of services: water sanitation,, viewed on 3May 2011.Anonymous, (2009), Rainwater Harvesting in Delhi, Rainwater Harvesting in Delhi,, viewed on 30 April 2011DVdesign, (2005),Aussie (2009), The Benefits of Getting a Rainwater Tank Installed,, viewed on 30 April 2011Australian government department of health and ageing (2004), Guidance on Use of Rainwater Tanks, ISBN 0 64282443 6, Australian government, publications production unit (Corporate support branch), PDF files, page 2 Http:// , visited on 2May 2011Bacha (2008), Rainwater harvesting for domestic use,, viewed on 2 May 2011,Dupont. P, (2010), Technical Manual: Rainwater, Australias guide to environmentally sustainable homes website, visited on 30 April 2011Harvesting (2005), Rainwater Tanks: Which rainwater tank is ideal for rainwater harvesting, Rainwater harvestingguide website, visited on 1 May 2011Jay R.Smith (2009), division of smith industries, A green idea: advantages of rainwater harvesting, viewed on 2 May2011Lili (2009), Low-impact living initiative: Rainwater Harvesting,, visited on 3 May 2011Meteorological Department Malaysia (2010), Monthly Weather Bulletin,, viewed on 1 May 2011Rainwater, website,, viewed on 29 April 2011APPENDICESSharifah Nur AzureenTang Sieu Wei 7
  8. 8. HES 3112 –Water Resource Engineering 2011Figure 1: Rainfall Amount (January 2011)Figure 2: Rainfall Amount (December 2011)8 The Use of Rainwater Tanks to Supplement Water Supplies: Urban Water Issue Assignment