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Sustainability of Rain Water Harvesting System in Terms of Water Quality: A Case Study

Wiley
The Scientific World Journal
Authors:
  • Heriot-Watt University, Malaysia

Abstract and Figures

Water is considered an everlasting free source that can acquire 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 non-potable, purposes both in residential and commercial buildings. This could reduce the pressure on processed supply water which enhances the green living. This paper ensures the sustainability of this system through assessing several water-quality parameters of collected rain-water 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 etc. The study reveals that the overall quality of water is quite satisfactory as per Bangladesh standards. RWH system offers sufficient amount of water and energy savings through lower consumption. Moreover, considering the cost for installation and maintenance expenses, the system is effective and economical. Keywords cost; deficit; demand; energy; rainwater harvesting; saving; supply; water quality
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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 oers sucient amount of water and energy savings through lower consumption.
Moreover, considering the cost for installation and maintenance expenses, the system is eective 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-
nicant 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 dierent 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,
scientic 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 Scientic World Journal
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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 aect 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
andalsoonthenancialbenetacquiredbyusingthis
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
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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 fulll 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 aecting
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 decit is about
.MLD.Asdemandismorethanjustsuppliedwater,
decit prevails, which is increasing every day. erefore the
water crisis becomes a normal issue due to this huge decit
in Dhaka City during the dry period. e trend of decit
is due to dierence 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
decit also crosses predicted values. In  the decit was
 ML, and in  it became  ML, which was more than
calculated. But aer 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 deciency 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 decit with
thepresentsupplyandvariationofthepopulationfor
e Scientic World Journal
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Demand/supply (ML)
Ye a r
Demand of water
Supply of water
Water decit
1996
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1990
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F : Relation among water demand, supply, and decit in
Dhaka City [].
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2011 2015 2020 2025 2030
Population (million)
Present supply/decit (MLD)
Ye a r
Decit (with present water supply) (MLD)
Present supply (MLD)
Population (million)
F : Present water supply, shortage, and population variation
for projected years.
0
50
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150
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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 decit 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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90
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Relative humidity (%)
Months
Relative humidity
F : Monthly average relative humidity (%) in Dhaka City.
0
5
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25
30
35
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 inltration 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 rooop and manage it on his own. Reserved rainwater on
rooops can be used for self-purposes or domestic use. Water
from dierent rooops 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 Scientic 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 retrotted [].
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 ecient 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 eective 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 identied 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 eective 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
coecient.
e Scientic 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 coecient 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, .
Signicant 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
signicant 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 benets 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 dierent 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
50
100
150
200
250
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 . Aer 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 aer 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 Scientic 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
enancial benet 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 Scientic 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
becollectedwithinsq.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
benet between a rainwater harvesting system and traditional
water supply system encountered and revealed a rainwater
harvesting system as a cost-eective 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
sucient quantity of water with small cost. Hence, the system
can promote signicant 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. []analyzedhouses
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 signicant
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
andapproximatelykWhelectricitycouldbesavedinthe
selected residential building by introducing rainwater cap-
turing system. Integrating rainwater harvesting system with
the conventional water collection and distribution approach
e Scientic 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 sucient
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 benets 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 eciencies 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-benet analysis should be per-
formed on dierent 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 quantication
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 diculties. Rainwater harvesting
is an eective 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 eectiveness 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 eective 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 Scientic World Journal
andutilizedbytherespectiveauthoritiesaswellasbythecity
dwellers.
Conflict of Interests
e authors declare that there is no conict 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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... The motivation behind urban pond reclamation and upgrading, addressing urbanization challenges like stormwater runoff, flooding, and water scarcity, aligns with sustainable urban water management goals (UNEP, 2009). This process yields multiple benefits, encompassing enhanced water quality, biodiversity conservation, flood control, and rainwater harvesting (Rahman, 2014). Reclaimed ponds act as natural filters, fostering healthier water systems and providing habitats for local flora and fauna. ...
... Rainwater Harvesting and Conservation: Promoting rainwater harvesting techniques and water conservation practices is crucial, especially in regions where rainfall is a primary water source (Rahman et al. 2014). Capturing and storing rainwater for agricultural and domestic use help supplement water supply during dry periods and reduce reliance on unsustainable groundwater extraction. ...
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Ghana’s cultural diversity is a mosaic of traditions, languages, and expressions that contribute to the country’s vibrant identity. Efforts to preserve and celebrate this diversity are crucial for the continued flourishing of Ghana’s cultural heritage and water resources. Sustainable management of water resources entails meeting current water demands while ensuring that the needs of future generations can also be met without depletion. This chapter reviews the value of cultural diversity in Ghana to water resource management. It discusses water sustainability as well as water resource management systems and practices in Ghana and their implications for sustainable development. The Ghana Water Resource Commission regulates the water resources of the country but suffers from a gross lack of funding, insufficient staffing, and necessary technical capacity to create and implement effective water management plans. Some key water sustainability challenges in Ghana include water scarcity and stress, inadequate access to clean water, poor infrastructure, excess groundwater withdrawal, climate change, capacity building, and water quality monitoring and management. Since the pre-colonial period, traditional leaders effectively managed water resources, employing various cultural methods and practices to ensure their preservation and responsible usage. Some of the practices include designation as sacred sites; community-led water governance and monitoring; use of proverbs, taboos, totemism, and folklore to convey messages about the importance of water conservation and wise water use; water festivals; awareness of healing properties of water; and traditional water technologies like wells and dugouts. Therefore, the traditional water management system reinforces the connection between people and their environment as water management activities influence culture and the management practice is influenced and shaped by culture onto sustainability. In conclusion, the integration of traditional practices, community involvement, and modern technologies contributes to a comprehensive and sustainable water management system.
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Water is a crucial and indispensable resource, essential for a myriad of daily activities. In Dhaka, Bangladesh, the issue of water scarcity has reached alarming levels, underscoring the urgent need to explore new water sources. Despite the critical situation, there is still a significant gap in comprehensive research and identification of alternative water sources. In this context, a holistic approach including geographic information system was adopted, integrating multi-criteria decision analysis with the analytic hierarchy process, to meticulously assess the most viable zones and rooftops for effective rainwater harvesting. To evaluate the potential water yield through rainwater harvesting, the Soil Conservation Service Curve Number method was used to approximate the rainfall-runoff dynamics in the study area. The findings indicated that about 23% of the total area is highly conducive for implementing rainwater harvesting, whereas 62% and 15% of the areas were deemed moderately and poorly suitable, respectively. Results showed that among the 6291 existing roofs in the study area, approximately 10% fell into the good condition category for rainwater harvesting. Additionally, the rainfall-runoff estimation analysis revealed that during the wet seasons, harvested rainwater could potentially meet up to 40–59% of the total water demand of Dhaka's extensive population. Recognizing the potential of rainwater harvesting and its capacity to contribute to water demand empowers policymakers to devise strategies and policies promoting sustainable water usage. This effort is pivotal in conserving and efficiently using water resources, ensuring their long-term availability and resilience amidst escalating water demand and challenges.
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A major portion of Bangladesh is currently experiencing a scarcity of safe drinking water because of arsenic contamination, high salinity and human-induced pollution. The objectives of this study were to identify locations with a high scarcity of drinking water and suitability of harvesting rainwater. Kriging interpolation algorithms of Geographical Information System (GIS) was employed to identify the probable water scarce zones as well as suitable zones of harvesting rain water from the available data of secondary sources. Statistical methods were employed to cluster, correlate, and regress variables such as rainfall, salinity, and As. The results showed that groundwater quality in the southwestern parts of Bangladesh is saline with high concentration (>10000 μS/cm). On the other hand, the northeastern and southwestern parts of Bangladesh are also vulnerable to arsenic contamination (60 %-97 % of tubewells), compared to other regions. The rainfall zonation map, covering the years 1951-2022, indicated that the Sylhet division had the highest potential for rainfall (ranging from 2600 to 3900 mm). From this study it was demonstrated that Sylhet, Noakhali, Bhola, Barishall, Patuakhali, Bagerhat, and Khulna were identified as suitable places for sustainable rainwater harvesting (RWH). The findings of this study may play significant role towards achieving sustainable potable water supply in vulnerable zones, if they receive attention from policymakers.
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Kebutuhan akan air pada era adaptasi kebiasaan baru setelah pandemic covid 19 semakin bertambah. Hal ini meningkatkan permasalahan kelangkaan air yang menjadi tantangan khususnya bagi masyarakat di daerah karst. Penelitian ini bertujuan untuk mendapatkan desain pemanenan air hujan yang paling optimal untuk memenuhi kebutuhan air bersih masyarakat. Pemanenan air hujan adalah strategi dalam rangka memberikan solusi alternatif pada daerah yang menghadapi tantangan terkait pemenuhan air bersih. Kebutuhan air per orang per hari adalah 7L mengacu pada ketentuan dari World Health Organization (WHO). Data yang digunakan adalah data harian curah hujan satelit Tropical Rainfall Measuring Mission (TRMM) periode Januari 2003 hingga Desember 2019. Pemilihan data satelit didasarkan pada pertimbangan kontinuitas data dan telah dikorelasikan dengan nilai curah hujan pengamatan dari pos hujan Stasiun Geofisika Bandung. Metode yang digunakan untuk analisis volume tampungan air hujan optimal merupakan modifikasi dari sistem operasi waduk. Hasil analisis menunjukkan bahwa sistem pemanenan air hujan pada daerah penelitian dapat digunakan sebagai alternatif sumber air bersih dengan indeks keandalan 80%. Desain tampungan yang paling optimal untuk diusulkan yaitu model 2 buah tampungan dengan kapasitas masing-masing sebesar 20 m3.
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Purpose At present, many urban areas in Mediterranean climates are coping with water scarcity, facing a growing water demand and a limited conventional water supply. Urban design and planning has so far largely neglected the benefits of rainwater harvesting (RWH) in the context of a sustainable management of this resource. Therefore, the purpose of this study was to identify the most environmentally friendly strategy for rainwater utilization in Mediterranean urban environments of different densities. Materials and methods The RWH systems modeled integrate the necessary infrastructures for harvesting and using rainwater in newly constructed residential areas. Eight scenarios were defined in terms of diffuse (D) and compact (C) urban models and the tank locations ((1) underground tank, (2) below-roof tank, (3) distributed-over-roof tank, and (4) block tank). The structural and hydraulic sizing of the catchment, storage, and distribution subsystems was taken into account using an average Mediterranean rainfall, the area of the harvesting surfaces, and a constant water demand for laundry. The quantification of environmental impacts was performed through a life cycle assessment, using CML 2001 Baseline method. The necessary materials and processes were considered in each scenario according to the lifecycle stages (i.e., materials, construction, transportation, use, and deconstruction) and subsystems. Results and discussion The environmental characterization indicated that the best scenario in both urban models is the distributed-over-roof tank (D3, C3), which provided a reduction in impacts compared to the worst scenario of up to 73% in diffuse models and even higher in compact ones, 92% in the most dramatic case. The lower impacts are related to the better distribution of tank weight on the building, reducing the reinforcement requirements, and enabling energy savings. The storage subsystem and the materials stage contributed most significantly to the impacts in both urban models. In the compact density model, the underground-tank scenario (C1) presented the largest impacts in most categories due to its higher energy consumption. Additionally, more favorable environmental results were observed in compact densities than in diffuse ones for the Global Warming Potential category along with higher water efficiencies. Conclusions The implementation of one particular RWH scenario over another is not irrelevant in drought-stress environments. Selecting the most favorable scenario in the development of newly constructed residential areas provides significant savings in CO2 emissions in comparison with retrofit strategies. Therefore, urban planning should consider the design of RWH infrastructures using environmental criteria in addition to economic, social, and technological factors, adjusting the design to the potential uses for which the rainwater is intended. Recommendations and perspectives Additional research is needed to quantify the energy savings associated with the insulation caused by using the tank distributed over the roof. The integration of the economic and social aspects of these infrastructures in the analysis, from a life cycle approach, is necessary for targeting the planning and design of more sustainable cities in an integrated way.
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This study was conducted to determine the present status of groundwater level in Dhaka city. During 2005, about 1.6 Mm3 day-1 of groundwater was withdrawn by Dhaka Water Supply and Sewerage Authority (DWASA) against the city's total demand of 2.1 Mm3 day-1. Compared to the exploitation of groundwater, the recharge to aquifer is very negligible as the geological settings and urbanization has retarded both the vertical and horizontal recharges. Consequently, groundwater table is continuously declining at an average rate of 2 m year-1 since, 1986. Continuous groundwater mining has caused the dry season water table to move downward from -54 to -45 m depth from the sea level. The severe decline of groundwater level was observed in the central part of the city, compare to the river periphery, creating a cone of depression. If this falling trend of the groundwater level continues that might create an increased pressure on water storage and may invite land subsidence or other environmental hazards. So, the aquifer requires sustainable management to protect future water quality and to ensure that the resource can continue to meet the quantitative demands being placed upon it.
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Despite continuous monitoring of public water supplies by governmental agencies, little is done for monitoring the water qualit ns and tanks receiving rainwater. For this reason, it is very important to evaluate the quality of rainwater collect ored in these cisterns and storage tanks. In the present work, a comprehensive survey was carried out to cover four Ninet analy biolo for do catch drink y of cister ed and st governorates in northern region of Jordan, where rainwater collection for domestic use is practiced on regular basis. y samples of harvested rain water from various storage tanks within these four governorates were collected and zed for different quality parameters (pH, alkalinity, Hardness, Turbidity, TDS, COD, NO 3 , NH 4 , PO 4 , Pb, Fe, Cr and gical contaminations). The results of the analysis were compared with valid quality guidelines to evaluate its suitability mestic uses. The resulted data indicate that water quality in these tanks and cisterns varies depending on location, on ment area, and on the availability of public sanitary systems. It was concluded that collected rainwater is unsuitable for ing purpose while it could be used for irrigation within in houses.
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In this study, the development and performance of rainwater utilisation systems in Germany are described. Initially the operational characteristics of the different types of rainwater utilisation systems are explained. The objective of the modelling-based investigations is to quantify the effects of rainwater usage systems on the urban drainage system. On the basis of a long-term simulation of 10 years rain data, the following parameters were calculated: tank volumes, covering efficiency, drinking water savings, overflow occurrence, overflow volumes, overflow reduction, recurrence time of overflows. The water balance of a one-family house and a multi-storey building in Bochum was calculated in a case study.
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Rainwater samples were collected from rainwater harvesting (RWH) systems at seven sites located in a 30 km radius around the City of Guelph in Ontario, Canada. From October 2006 to October 2007, a total of 360 samples were collected from two sampling locations-the rainwater cistern and at the point of use-and analysed for pH, turbidity, colour, total and fecal coliforms, total organic carbon, total nitrogen and UV absorbance (254 nm). Additional parameters, including polycyclic aromatic hydrocarbons, total metals, Campylobacter and Legionella were examined in selected samples. Following data collection, statistical analysis was performed to investigate the factors that influenced rainwater quality. The results of the quality assessment programme were largely consistent with those reported by several other researchers, with the exception of improved microbiological quality during periods of cold weather. Total and fecal coliforms were detected in 31% and 13% of the rainwater samples, respectively, while neither Campylobacter nor Legionella were detected above 1 CFU/100 ml detection limits. The results indicate that, while quality can be expected to vary with environmental conditions, the rainwater from a RWH system can be of consistently high quality through the selection of appropriate catchment and storage materials and the application of post-cistern treatment.
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Rainwater tanks have become popular in large Australian cities due to water shortage and greater public awareness towards sustainable urban development. Rainwater harvesting in multi-unit buildings in Australia is less common. This paper investigates the water savings potential of rainwater tanks fitted in multi-unit residential buildings in three cities of Australia: Sydney, Newcastle and Wollongong. It is found that for multi-unit buildings, a larger tank size is more appropriate to maximise water savings. It is also found that rainwater tank of appropriate size in a multi-unit building can provide significant mains water savings even in dry years. A prediction equation is developed which can be used to estimate average annual water savings from having a rainwater tank in a multi-unit building in these three Australian cities.
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This paper studies the effect of drought and pumping discharge on groundwater supplies and marine intrusion. The investigation concerns the Mamora coastal aquifer, northwest of Morocco. A large-scale groundwater model was established to model (a) the amount of freshwater discharge towards the ocean and the sea water volumes flowing inland as a consequence of the inverse hydraulic gradient, (b) the impact of drought and pumping discharge on the water table level and, as a consequence, on marine water intrusion. In fact, the simulated submarine groundwater discharge (SGWD) would decrease from 864 m3/d/km in 1987 to 425 m3/d/km in 2000. The simulated volumes of sea water intruding the aquifer as a result of inverse hydraulic gradient would increase from 0·25 Mm3/y in 1987 to 0·3 Mm3/y in 2000. As a consequence of a negative rainfall gradient of −5 mm/y, the simulated SGWD would decline to 9 m3/d/km and the sea water intrusion (SWI) would increase to 0·35 Mm3/y since the year 2010. Due to insufficient data on the trend of pumping discharge, a hypothetical increase of this latter from 38·3 Mm3/y to 53·2 Mm3/y is simulated to induce an increase of marine water intrusion from 0·25 Mm3/y to 0·9 Mm3/y. Consequently, to optimally exploit this seemingly fragile coastal aquifer, a plan of future actions to implement is proposed. Copyright © 2005 John Wiley & Sons, Ltd.