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Research Article
Sustainability of Rainwater Harvesting System
in terms of Water Quality
Sadia Rahman,1M. T. R. Khan,2Shatirah Akib,1Nazli Bin Che Din,2
S. K. Biswas,3and S. M. Shirazi4
1Department of Civil Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia
2Department of Architecture, Faculty of Built Environment, University of Malaya, 50603 Kuala Lumpur, Malaysia
3Department of Civil Engineering, Bangladesh University of Engineering & Technology, Dhaka 1000, Bangladesh
4Institute of Environmental and Water Resources Management (IPASA), Faculty of Engineering,
Universiti Teknologi Malaysia, 81310 Johor, Malaysia
Correspondence should be addressed to Sadia Rahman; sadia rahman@yahoo.com
Received November ; Accepted January ; Published February
Academic Editors: N. Drouiche and E. P. Meulenberg
Copyright © Sadia Rahman et al. is is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Water is considered an everlasting free source that can be acquired naturally. Demand for processed supply water is growing higher
due to an increasing population. Sustainable use of water could maintain a balance between its demand and supply. Rainwater
harvesting (RWH) is the most traditional and sustainable method, which could be easily used for potable and nonpotable purposes
both in residential and commercial buildings. is could reduce the pressure on processed supply water which enhances the green
living. is paper ensures the sustainability of this system through assessing several water-quality parameters of collected rainwater
with respect to allowable limits. A number of parameters were included in the analysis: pH, fecal coliform, total coliform, total
dissolved solids, turbidity, NH3–N, lead, BOD5, and so forth. e study reveals that the overall quality of water is quite satisfactory
as per Bangladesh standards. RWH system oers sucient amount of water and energy savings through lower consumption.
Moreover, considering the cost for installation and maintenance expenses, the system is eective and economical.
1. Introduction
Dhaka is a densely populated city with an area of km2
[] which is already labelled as a mega city [–]. is sig-
nicant population craves a larger amount of water for dif-
ferent purposes. erefore, there is always a shortcoming
of supplied water due to an imbalance between demand
and supply. Dhaka Water Supply and Sewerage Authority
(DWASA) is the only authoritative organization available to
deliver consumable water to Dhaka City dwellers. DWASA []
provides % of total demand of water in which about % is
accumulated from groundwater sources, and the remaining
% is collected from dierent treatment plants. Dhaka
presently relies heavily on groundwater, with approximately
to % of demand coming from this source. Overreliance
on groundwater sources is depressing the water level. Every
year the groundwater table is dropping down around to m
due to the extreme amount of withdrawal. Figure shows the
groundwater level depletion trend for Dhaka City. Moreover,
scientic studies on the groundwater revealed that excessive
exploitation has been lowering the aquifer level, thus limiting
natural recharge [,]. Additionally, overexploitation for
longer periods may account for several natural hazards such
as unexpected landslides, sustained water logging, reduction
in soil moisture, and changes in natural vegetation [,–].
Conjunctive use of groundwater and surface water would
be one potential solution to reduce heavy reliance on ground-
water. Surface water treatment plants are treating polluted
water before delivering it to a supply pipeline. But the level
of pollution of surface water has limited the applicability of
the treatment process. DWASA supplies . million liters
of water daily against the current demand for . million
liters [], which indicates that the city is facing a huge shortage
of water daily. All the scenarios between water demand and
supply prevail the immediate need for adopting alternative
solutions to release the pressure on water sources. Moreover,
Hindawi Publishing Corporation
e Scientific World Journal
Volume 2014, Article ID 721357, 10 pages
http://dx.doi.org/10.1155/2014/721357
e Scientic World Journal
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2011
2012
2013
Ground water depth (m)
F : Groundwater depletion in Dhaka City [].
current water practices have limited attention to the climate
change impacts on water availability []. Surveys on climate
projections provide evidence on critical impacts of climate on
natural water sources that eventually aect human societies
and ecosystems [].
Rainwater harvesting (RWH) could be the most sustain-
able solution to be included in the urban water management
system. It could mitigate the water crisis problem, reduce
the burden on traditional water sources, alleviate nonpoint
source pollutant loads, control water logging problems, pre-
vent ooding, help in controlling climate change impacts,
contribute to the storm water management, and so forth [–
]. Water scarcity and the limited capacity of conventional
sources in urban areas promote RWH as an easily accessible
source []. e system could be utilized locally and com-
mercially for securing water demand in water-scarce areas all
around the world. Harvested rainwater could be idealized and
used like supply water if the water-quality parameters satisfy
the desired level. e monitoring of collected rainwater is of
great concern as it is the potential for health risk because of
the presence of chemical and microbiological contaminants
[]. erefore quality assessment of collected water is essen-
tial before use. is paper is mainly focused on scrutinizing
and assessing water-quality parameters as per allowable limit
andalsoonthenancialbenetacquiredbyusingthis
technique. Finally this paper suggests a rainwater harvesting
system as a potential source of water supply in Dhaka City.
2. Water Scenario in Dhaka City
About % of total demand of water in Dhaka is supplied by
DWASA, and the rest comes from privately owned tube wells.
At present DWASA can yield about . million liters
(ML) [] per day in which about . MLD is collected
from deep tube wells (DTW), and the remaining
. MLD is supplied by two surface water treatment plants
[]. More details are given in Figure .
Buriganga, Balu, Turag, and Tongi Khal are the main
four water bodies surrounding the city and could be an
ideal sources of water supply [,].Butthesewaterbodies
alreadylosttheirpotentialityassourcesofsupplyduetothe
huge pollutions. Untreated municipal and industrial wastes
make the river water so contaminated that most of the water
quality parameters surpassed their allowable level. However,
the water supply authority mainly relies on groundwater
2516.53
299.17
2815.7
1840.04
252.65
2092.69
0
500
1000
1500
2000
2500
3000
Ground water Surface water Total
Production (MLD)
Sources
Production capacity
Actual production
F : Water production per day in Dhaka city [].
sources and needs to install more tube wells to fulll demand
[,]. Installation of more tube wells must lower the
groundwater level. erefore it is urgent to nd a sustainable
solution that could alter the usage of groundwater. Rainwater
harvestingwouldbeoneofthemostconceivableandviable
solutions to release the pressure on the groundwater table
as the system utilizes natural rainwater without aecting
groundwater sources.
3. Water Supply and Demand Variation
In order to understand the variation between demand and
supply, the total demand needs to be known. at could be
calculated through population data and per capita demand.
According to Bro [], per capita demand for was
about liters, including % provisions for commercial
use and % due to system loss during supply. As per capita
demandwillbeassumedtobedecreasedinthefutureby
proper inspection and management, for the total per
capita demand will stand at liters per day and for
and at liters per day. According to DWASA,
[], the water supply is about . MLD (considering
service ow with % leakages), and the total demand is
MLD (assuming % service area). So the decit is about
.MLD.Asdemandismorethanjustsuppliedwater,
decit prevails, which is increasing every day. erefore the
water crisis becomes a normal issue due to this huge decit
in Dhaka City during the dry period. e trend of decit
is due to dierence in demand and supply as shown in
Figure . In the total demand was million liters
(ML), which turned into million liters in due to
the augmentation of the population. Within years demand
became times more than expected. In a similar way, the
decit also crosses predicted values. In the decit was
ML, and in it became ML, which was more than
calculated. But aer that, the shortage became something
better than in the previous year. is indicates that supply
capacity is improving, and authorities are trying to reduce the
shortages. e overall deciency of supplied water triggers
the need for augmentation and improvement of the water
supply system to meet the increased demand in future [].
Figure shows the variation of the water decit with
thepresentsupplyandvariationofthepopulationfor
e Scientic World Journal
0
500
1000
1500
2000
2500
Demand/supply (ML)
Ye a r
Demand of water
Supply of water
Water decit
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
1990
1980
1970
1963
F : Relation among water demand, supply, and decit in
Dhaka City [].
0
5
10
15
20
25
30
0
500
1000
1500
2000
2500
3000
3500
4000
2011 2015 2020 2025 2030
Population (million)
Present supply/decit (MLD)
Ye a r
Decit (with present water supply) (MLD)
Present supply (MLD)
Population (million)
F : Present water supply, shortage, and population variation
for projected years.
0
50
100
150
200
250
300
350
400
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Rainfall (mm)
Months
Rainfall
F:MonthlyaveragerainfallinmminDhakaCity.
the projected years. If the present supply prevails for the
coming years, the decit of water will be increasing to a
high amount that could not be alleviated within the allowable
limit.
Dhaka is located in a hot and humid country, and its
annual temperature (∘C) categorizes the city as monsoon
climate zone. e city is blessed by a huge amount of rainfall
during the monsoon period, which poses ample opportunity
to use this rainwater in a sustainable manner []. Figures ,
,andshow the monthly rainfall pattern, monthly average
relativehumidity,andthemaximumandtheminimum
monthly temperature trend, respectively, for Dhaka City.
0
10
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80
90
Jan
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Relative humidity (%)
Months
Relative humidity
F : Monthly average relative humidity (%) in Dhaka City.
0
5
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40
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Months
Maximum temperature
Minimum temperature
Temperature (∘C)
F : Maximum and minimum temperature (∘C) trend in
Dhaka City.
e common practices of recharging natural aquifers
are by direct rainfall, river water, and direct inltration and
percolation during oods []. Overpopulation makes these
options inappropriate by reducing the recharge area. Cover-
ing the vertical recharge inlets with pavement materials or
other construction materials can cause water logging for even
small duration heavy rainfall in most areas of Dhaka City.
Inadequate storm water management infrastructures and
improper maintenance of storm sewer systems further aggra-
vates the scale of this problem. Harvesting of this storm water
in a systematic way thus prevents water logging. Furthermore,
utilization of collected rainwater highly releases the depen-
dency on groundwater sources.
4. Rainwater Harvesting
Rainwater harvesting is a multipurpose way of supplying
usable water to consumers during a crisis period, recharging
the groundwater and nally reducing the runo and water
logging during the season of heavy rainfall. Traditional
knowledge, skills, and materials can be used for this system.
During the rainy season, an individual can collect water on
his rooop and manage it on his own. Reserved rainwater on
rooops can be used for self-purposes or domestic use. Water
from dierent rooops of a lane can also be collected through
a piped network and stored for some time. is water can
be then channeled to deep wells to recharge groundwater
e Scientic World Journal
Roof collection area
Gutter
Storage
tank
Downspout
Hose bib
First
flush
lter
Clean
out
plug Bottom
full valve
Overflow
valve
F : Schematic of a rainwater harvesting system.
directly, to ponds to replenish groundwater slowly, and to
reservoirs to dilute reclaimed water for nonpotable use.
Figure shows the schematic view of a rainwater harvesting
system.
Unless it comes into contact with a surface or collection
system, the quality of rainwater meets Environmental Pro-
tection Agency standards [], and the independent charact-
eristic of its harvesting system has made it suitable for
scattered settlement and individual operation. If needed, a
chemical treatment such as chlorination can be used to purify
the water. e acceptance of rainwater harvesting will expand
rapidly if methods are treated such as building services and if
designed into the structure instead of being retrotted [].
5. Benefits of Rainwater Harvesting
Rainwater harvesting is a simple and primary technique of
collecting water from natural rainfall. At the time of a water
crisis, it would be the most easily adaptable method of
mitigating water scarcity. e system is applicable for both
critical and normal situations. It is an environmentally fri-
endly technique that includes ecient collection and storage
that greatly helps local people. e associated advantages of
rainwater harvesting are that
(i) it can curtail the burden on the public water supply,
which is the main source of city water;
(ii) itcanbeusedincaseofanemergency(i.e.,re);
(iii) it is solely cost eective as installation cost is low, and
it can reduce expense that one has to pay for water
bills;
(iv) it extends soil moisture levels for development of
vegetation;
(v) groundwater level is highly recharged during rainfall.
6. Quality of Rainwater
e quality of harvested rainwater is an important issue, as it
could be utilized for drinking purposes. Quality of captured
water from roof top depends on both roof top quality and
surrounding environmental conditions, that is, local climate,
atmospheric pollution, and so forth []. Tests must be per-
formed to check its viability and applicability before using
as drinking water. Previous researches [–]showedthat
water quality of collected water did not always meet standard
limits due to unprotected collection. Local treatment of
harvested water could easily make water potable. Again rain-
water could be also identied as non-potable sources for the
purpose of washing, toilet ushing, gardening, and so forth,
wherequalityisnotagreatconcern.Inthisrespect,treatment
of collected water is of no such importance; rather it is used
for household purposes. In this paper an assessment has been
made on the quality of rainwater collected through a well-
maintained catchment system.
7. Methodology
Rainwater harvesting is a more eective technology that
could be easily undertaken through normal equipment dur-
ing a water crisis. Qualitative assessment is important before
introducing collected rainwater as potable water. In this
paper,acasestudyhasbeenmadetocheckrainwaterquality
to identify its acceptability and suitability as household water.
Water samples were collected from the selected residential
building where a rainwater harvesting system was introduced
successfully using laboratory prepared plastic bottles to col-
lect samples. e samples were bottled carefully, so that no air
bubble is entrained in the bottle. All parameters were mea-
sured in the environment laboratory of Bangladesh Univer-
sityofEngineeringTechnology(BUET).
e maximum amount of rainwater that could be enco-
untered from a roof top is
𝑉=𝐴×𝑅×𝐶, ()
where 𝑉is the amount of harvestable water, 𝐴is catchment
area, 𝑅is total amount of rainfall, and 𝐶is the runo
coecient.
e Scientic World Journal
5
5.5
6
6.5
7
7.5
8
pH
Time
Flush water
Tank water
EQS [32]
Oct-10
Nov-10
Dec-10
Jan-11
Feb-11
Mar-11
Apr-11
May-11
Jun-11
Jul-11
Aug-11
Sep-11
Oct-11
F : Variation of pH over time.
Equation ()wasusedtocalculatetheamountofhar-
vested water from a residential building located at Dhaka,
Bangladesh. e system was designed for meeting water
requirements of persons living in the entire building. Total
area was about sq. . (square feet). Maximum ground
coverage would be around sq. . (considering the oor
area rule of RAJUK, the city development authority), and
within this area sq. was used as catchment area where
rainwater was collected. Per capita water consumption is
about lpcd for conservative use. e total demand for this
building stands at about liter per day and , liters
per month. In a practical case, the size of the catchment area
is taken from maximum ground coverage. To get an overview
of the amount of collected rainwater, monthly average rainfall
data from January to December has been considered, includ-
ing the dry and monsoon periods. e runo coecient value
was taken as .. For analysis purpose, a one-year rainfall
data were considered. Volume of collected rainwater was
also an important aspect in introducing rainwater for domes-
tic purposes. In the selected time frame, maximum volume
of water was collected during June, , which was about
. m3and a minimum was collected during October, .
Signicant amount of water could be collected during heavy
rainfall. From this point of view, it could be said that, with
larger catchment area, amount of harvested water would be
signicant to be used in household works.
8. Results and Discussion
e main focus of this paper relies on several aspects, such
as examining the quality of water with respect to standard
values, analyzing associated nancial benets in terms of cost,
and considering water and energy conservation and lastly
suggesting the system as a potential source of water both in
normal and critical situations.
In this section, the quality of harvestable water was
checked considering several parameters such as pH, fecal col-
iform, total coliform, total dissolved solids, turbidity, NH3–
N, lead, and BOD5. e time period for analysis was from
October to October . Two dierent collecting points
were considered: water collected before entering into the
storage tank (called rst ush water) and water collected from
the storage tank (tank water). Figure shows the variation
0
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300
350
400
450
Total coliform
Time
Flush water
Tan k w ate r
EQS [32]
Oct-10
Nov-10
Dec-10
Jan-11
Feb-11
Mar-11
Apr-11
May-11
Jun-11
Jul-11
Aug-11
Sep-11
Oct-11
F : Variation of total coliform over time.
0
50
100
150
200
250
300
350
400
450
Fecal coliform
Time
Flush water
Tank water
EQS [32]
Oct-10
Nov-10
Dec-10
Jan-11
Feb-11
Mar-11
Apr-11
May-11
Jun-11
Jul-11
Aug-11
Sep-11
Oct-11
F : Variation on fecal coliform with time.
of pH over time. According to Bangladesh standards for
drinking water [], the allowable limit for pH is . to ..
Results showed that pH value for both ash and tank water
was very near to this range during the tested time period.
erefore, the pH level of collected water did not pose any
threat to water quality and conformed to the standard limit.
Figure shows the variation of total coliform over time.
e number of total coliforms present in the water was quite
low until June . Aer that a large number of total coliform
grew in both ash and tank water. Figure shows the varia-
tion of fecal coliform over time. In the case of drinking water,
it is expected that water should be free from all types of fecal
and total coliforms. In the present case, at rst in October
, few fecal coliforms were found in water. It remains zero
until March . But aer that there was an increasing trend
in the number of fecal coliform. In October , there was
huge number of fecal coliform, which is not expectable for
drinking water. In both cases (fecal and total coliform), at
rst when rainwater was harvested, growth of coliform was
lower but with time those increased to a large quantity. From
June , rainfall was not adequate and maintenance was
not proper, which is why coliform grew to a huge quantity
inthestoredunusedwater.Aspurewatershouldbefree
e Scientic World Journal
0
200
400
600
800
1000
1200
Total dissolved solids (TDS) (mg/L)
Time
Flush water
Tank water
EQS [32]
Oct-10
Nov-10
Dec-10
Jan-11
Feb-11
Mar-11
Apr-11
May-11
Jun-11
Jul-11
Aug-11
Sep-11
Oct-11
F : Variation of total dissolved solids over time.
0
2
4
6
8
10
12
Turbidity (NTU)
Time
Flush water
Tank water
EQS [32]
Oct-10
Nov-10
Dec-10
Jan-11
Feb-11
Mar-11
Apr-11
May-11
Jun-11
Jul-11
Aug-11
Sep-11
Oct-11
F : Variation of turbidity over time.
from all kinds of coliforms, proper maintenance of tank and
catchment areas could minimize coliform level and make
rainwater safe for household purposes.
Figure shows the variation of total dissolved solids over
time. e allowable limit for total dissolved solids (TDS) in
drinking water is about (mg/L) according to Bangladesh
standards for drinking water [].Foralltheselectedperiods,
the total dissolved solids in collected water were quite lower
than the standard limit. erefore total dissolved solids did
notposeanythreattowaterusedfordrinkingpurposes.Fig-
ure shows the variation of turbidity over time. e standard
limit for turbidity is NTU. e measured turbidity level in
collected water was below this standard limit. erefore rain-
water could be considered satisfactory from an aesthetic point
ofview.Inasimilarway,theNH
3–N level was quite below
the standard limit (.mg/L) during the collection period
(Figure ).
0
0.5
1
1.5
2
2.5
Time
Flush water
Tank water
EQS [32]
Oct-10
Nov-10
Dec-10
Jan-11
Feb-11
Mar-11
Apr-11
May-11
Jun-11
Jul-11
Aug-11
Sep-11
Oct-11
NH3–N (mg/L)
F : Variation of NH3–N over time.
0
0.05
0.1
0.15
0.2
0.25
Months
Flush water
Tank water
EQS [32]
BOD5(mg/L)
Oct-10
Dec-10
Feb-11
Apr-11
Jun-11
Aug-11
Oct-11
F : Variation of BOD5over time.
Figure shows the variation of BOD5in the collected
ash and tank water. In all of the selected time period,
BOD5is less than the Bangladesh standard for drinking water
[]. Another thing, BOD5became less in ash water than in
tank water. Due to the lack of proper maintenance, BOD5
increased in the tank water. Further treatment may make
water more usable for household work. In order to analyze
the water quality in terms of lead concentration in collected
water, tests were performed, which found that lead concen-
tration always remained below the allowable limit according
to the Bangladesh standards for drinking water []. Figure
shows the variations of lead concentrations with time.
9. Cost Effectiveness Analysis
enancial benet associated with a rainwater harvesting
system is solely connected with cost. e associated costs
of a rainwater harvesting system are for installation, oper-
ation, and maintenance. Of the costs for installation, the
storage tank represents the largest investment, which can vary
between%and%ofthetotalcostofthesystemdepen-
dent on system size. A pump, pressure controller, and ttings
in addition to the plumber’s labor represent other major costs
of the investment. A practical survey showed that (in Dhaka)
thetotalcostrelatedtoconstructionandyearlymaintenance
of a rainwater harvesting system for years’ economic life
e Scientic World Journal
0
0.01
0.02
0.03
0.04
0.05
0.06
Lead (mg/L)
Months
Flush water
Tank water
EQS [32]
Oct-10
Dec-10
Feb-11
Apr-11
Jun-11
Aug-11
Oct-11
F : Variation of lead over time.
0
500
1000
1500
2000
0
10
20
30
40
50
60
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Harvestable rainwater (L)
Month
Harvestable rainwater (L)
Savings per month (BDT)
Savings per months
(BDT)
F : Month-wise harvestable amount of rainwater and the
associated cost savings.
is about BDT. is cost includes construction cost of
tanks, gutters, and ushing devices and labor cost []. In the
present case study, about . thousands liter water can be
harvested f rom rain over one year. is amount of water could
becollectedwithinsq.catchmentareaandconsidering
monthly rainfall data. e yearly consumption of this selected
building stands at thousands liters. erefore utilizing
harvested rainwater for this building can save up to % of
the public water supply annually. is volume of rainwater
can serve a building with members for about . months
inayearwithoutthehelpoftraditionalwatersupply.Figure
shows the month-wise harvestable amount of rainwater and
theassociatedamountofcostsavings.Furthermore,consid-
ering DWASA current water bill, about . BDT can be
savedperyear,andabout.BDTcanbesavedin
years if rainwater is used for daily consumption. So, within
three to four years, the installation cost of a rainwater har-
vesting system can be easily returned. Moreover, the building
owner would be exempted from paying large amount of
water bill as well as additional taxes and fees charged by
the city authority with the water bill if rainwater is utilized
for daily consumption. Cost comparison and associated
benet between a rainwater harvesting system and traditional
water supply system encountered and revealed a rainwater
harvesting system as a cost-eective technology.
T : Energy consumption in conventional water resources
system [].
Activity Energy consumption (kWh/MG)
Supply and conveyance
Wat e r t r e a t m e n t
Distribution ,
Total ,
10. Water Savings Strategy
Rainwater harvesting system plays an important role in
developing sustainable urban future []. Availability of water
of serviceable quality from conservative sources is becoming
limited day by day due to huge demand. Rainwater provides
sucient quantity of water with small cost. Hence, the system
can promote signicant water saving in residential buildings
in many countries. Herrmann and Schmida []studiedthat
potential saving of roof captures water was about –% of
potable water demand in a house depending on the demand
and catchment area. Coombes et al. []analyzedhouses
in Australia with rainwater harvesting system and found that
about%ofpotablewatercouldbesaved.Ghisietal.[]
performed investigation on collected rainwater in Brazil and
found that about –% of potable water could be saved
depending on the size of roof tank. Most of the researches
on rainwater harvesting systems (RWHS) revealed that water
conservation achieved through RWHS is quite signicant
especially in places where water is not easily available to
consumers.
11. Energy and Climate
Conventional use of water imparts critical impacts on nat-
ural resources. Water collection from ground and surface
sources, treatment, and distribution are closely associated
with energy consumption, however, being related to climate
consequences. e extraction of water from the sources, the
treatment of raw water up to the drinking standards and the
delivery of water to the consumers require high energy. More-
over, there should be some energy losses during performing
extracting, treating, and delivering of water. erefore, the
water sector consumes a huge amount of electricity from
local and national grid. Approximately billion kilowatt
hours of energy could be saved if potable water demand could
be reduced by % []. Adoption of RWHS is one of the
mostpotentialsolutionsthatcouldsaveenergydirectlyby
reducing potable water demand. Table represents the esti-
mated energy required to deliver potable water to consumers.
Reduction of water demand by million gallons can result
in savings of electricity use by , kWh. In the present case
study, with an sq. . catchment area, about , gallons
(. thousands liters) could be harvested over one year.
However, this amount could reduce potable water demand
andapproximatelykWhelectricitycouldbesavedinthe
selected residential building by introducing rainwater cap-
turing system. Integrating rainwater harvesting system with
the conventional water collection and distribution approach
e Scientic World Journal
T : Carbon dioxide emission from water treatment and
distribution system [].
Fuel type
COoutput rate
pounds
(CO/kWh)
Drinking water
energy demand
(kWh/MG)
COoutput rate
per MG water
delivered
(CO/kWh)
Coal . ,
Petroleum . , ,
Natural gas . ,
in residential as well as large scale, nonresidential applications
suggest a potential method of reducing energy use. However,
limiting energy demand has critical impact on carbon dioxide
emissions, as release of carbon dioxide is closely associated
with electricity generation. ere should have sucient
reductionincarbondioxideemissionswhenfossilfuelisused
for power generation. Hence, limited contribution is to be
expected from lower carbon release in climate change con-
cept. Table showed the carbon dioxide emissions from ele-
ctric power generation.
However, water use should be critically judged from
availability, safety, and sustainability of natural resources.
Energy conservation is a critical component in sustainabil-
ity concern. Decreased use of conventional potable water
reduces energy demand that in turn reduces emission of
carbon dioxide. Integrated water management approach with
rainwater harvesting along with gray water and reclaimed
water reuse could limit contributions to climate change and
conserve limited water and energy resources.
12. Future Action Plan
Rainwater is one of the advantageous methods of using
natural water in a sustainable manner. Rain is a blessing of
nature. Densely populated cities with a water crisis and ade-
quate rainfall should adopt this technology. Cities like Dhaka,
where water is a major concern during dry periods, should
introduce this system along with its traditional water supply
system. Pressure on groundwater tables thus could be pre-
vented, and natural recharging would also be proceeded
through this system. Regular maintenance of harvested water
might make it suitable for daily consumption. Water short-
ages will become the most concerned issue all around the
world in the future. erefore city planners should rethink
of the possibilities, outcome, and benets of a rainwater har-
vesting system and should create policies to make the system
easily available to everyone. e following research could be
made in future.
(i) is study focused only on rainwater harvesting
system on a small scale basis. Further research could
be performed on large scale residential, commercial
or industrial sector.
(ii) Comparisons could be made with rainwater harvest-
ing systems to conventional ground water system on
the basis of quality, quantity, environmental impacts,
energy saving, water conservation, economy, and so
forth.
(iii) Case studies could be investigated to evaluate energy
consumption in rainwater system with ground water
systeminalargescale.Inamoreappliedsetting,
energy eciencies of large scale rainwater harvesting
systems should be analyzed to help determine the
future of rainwater harvesting as a valuable tech-
nology for providing water, a crucial resource that
is becoming more depleted with the ever increasing
population and water demand.
(iv) A comprehensive cost-benet analysis should be per-
formed on dierent climate regions to get essential
insight on the economic viability of rainwater harvest-
ing system (RWHS).
(v) More detailed and advanced research on impacts
on climate factors, human health risk, and potential
ecological aspects should be performed in a large
scale.
(vi) More comprehensive studies for better quantication
of energy and climate factors should be made for
proper development of the system.
(vii) Rainwater could be highly polluted by pesticides in
any agricultural region. Hence, biological and chemi-
cal analysis should be done before adopting harvested
rainwater as a source of daily water.
13. Conclusion
WatershortageisoneofthecriticalproblemsinDhaka
City. is problem is not new one, and it cannot be solved
overnight. As DWASA relies on groundwater abstraction
through deep tube wells to overcome the excessive demand,
the water table is lowering day by day, and the recharge of
groundwater table is facing diculties. Rainwater harvesting
is an eective option not only to recharge the groundwater
aquifer but also to provide adequate storage of water for
future use. is paper tried to focus on the sustainability
and eectiveness of a rainwater harvesting system in terms of
quality. Water was collected in a well maintained catchment
system from rain events over one year and chemical analysis
was performed regularly to observe the quality of collected
water. e overall quality of rainwater was quite satisfactory
and implies that the system could be sustained during critical
periods as well as normal periods. Additionally, the system
is cost eective as large amounts of money can be saved per
year. Energy conservation and related reduced emissions are
crucial parts of this system. Moreover, increased awareness
on water crisis has led rainwater harvesting to be proposed as
a community facility. e small and medium residential and
commercial construction can adopt this system as sustainable
option of providing water. It is almost the only way to upgrade
one’s household water supply without waiting for the devel-
opment of community system. e system could become a
good alternative source of water supply in Dhaka City to cope
up with the ever-increasing demand and should be accepted
e Scientic World Journal
andutilizedbytherespectiveauthoritiesaswellasbythecity
dwellers.
Conflict of Interests
e authors declare that there is no conict of interests
regarding the publication of this paper.
Acknowledgments
e authors gratefully acknowledge the support of
Bangladesh University of Engineering and Technology
(BUET). is research is nancially supported by University
Malaya Research Grant (UMRG) RP/ and High
Impact Research Fund, Project no. UM.C///HIR/
MOHE/ENG/.
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