1. Water Quality in Mumbai: Chlorinated Compounds in
Potable Water
Dr.Prashant Bhave1
, Sourabh Kulkarni2
ABSTRACT:
Present study attempts to focus on the determination of chlorinated compounds like free
chlorine, total chlorine, mono-chloramines and chlorine dioxide (Cl-
, NH2Cl, ClO2) in
drinking water with the help of spectrophotometer using N,N diethyl-p-phenylenediamine
(DPD) method as per the “Standard methods for examination of Water & Wastewater”. The
reagent, stock solutions, standard solution and calibration curve was developed as per the
standard method (DPD method). The developed reagents accuracy was checked with the
commercially available kit/reagents (HACH spectrophotometer reagents). Sample was
collected randomly from different areas/ locations of Mumbai City. The results were
compared against the standards given by Govt. of India, WHO, and USEPA.
Keywords: Disinfection, Chlorination, DPD method, Spectrophotometer, Disinfection by-
products (DBPs)
INTRODUCTION
Drinking water is essential for life, yet it
can be a source of exposure to pathogens
and chemical, physical and
radiologicalcontaminants [1].
For
waterborne pathogens, including bacteria,
viruses, and protozoa, drinking water is a
major contributor to human exposures[1].
A
California think tank reported that as many
as 76 million children could die worldwide
from water-borne diseases by 2020 if
adequate safeguards are not taken [2].
It is
reported that of the 1.42 million villages in
India, 1, 96,813 villages are affected by
chemical contamination of water [Deccan
Helard, 2005]. Delhi’s water supply is
among the worst in many big cities of the
developing world [2]
. The Central Pollution
Control Board has found that the tap water
in Delhi contains carcinogenic substances
and the toxic quotient is five times higher
than the standards [2]
.So, it is accepted
globally that the quality of water is the
most important from health point of view
and to control the spread of diseases. There
is various disinfection techniques used
globally such as by ozone, UV rays etc[4,6].
But they are expensive for treating high
volumes of water. The most popular
disinfectant used all over the world from
five decades has been chlorine, but in
recent years the chlorine has become a less
popular due to the formation of
disinfection by- products(DBPs) including
Trihalomethane (THMs) and Chloramines
which results in health problem[4].
It is
well-known that chlorination of drinking
water leads to the formation of disinfection
by-products (DBPs) including chloramines
(referred as combined chlorine) or
trihalomethanes (THMs) (florentin et al,
2011).The formation of DBPs occurs with
natural or imported (xenobiotic) organic
and inorganic materials present in the
water (florentin et al, 2011).Chlorine is
produced in large amounts and widely
used both industrially and domestically as
an important disinfectant. It is most
commonly used disinfectant and oxidant in
drinking-water treatment [WHO, 2000].
Chlorine is widely used as a disinfectant
due to its effectiveness as a oxidising
compound, cost effective than UV or
ozone disinfectant, disinfection is reliable,
provides residual concentration, removes
odour, taste [WHO, 2000]. It is a less
popular due to its formation of by-

2. products; less effective in high pH,
residual is unstable in water [WHO, 2000].
Chlorine in water combines with natural
organic compounds NOM to yield a large
range of Chlorine disinfection by-products
(DBPs) such as trihalomethanes(THMs),
haloacetic acids (HAAs), chlorophenols,
phenolic acids, chlorinated quinines
exhibits potentially carcinogenic,
teratogenic and mutagenic activities to
human health [Rosalam, 2007]. Killing
effect of chlorine dioxide on bacteria is
similar to or better than that of liquid
chlorine at wider range pH [Junali et al,
1996].
Disinfection
Water treatment processes such as,
coagulation, flocculation, sedimentation,
filtration, aeration and water softening are
designed to produce water that are
aesthetically acceptable and economical
[CPHEEO, 1999]. The chlorination
process in the drinking water distribution
system (DWDS) has been practicedin
many countries to encounter the water
borne diseases [Rosalam, 2007].The
mechanism of killing pathogens depends
largely on the nature of the disinfectant
and on the type of microorganism and
destruction can be done by damage to cell
wall, alternation of cell permeability,
Changing the colloidal nature of the cell
protoplasm, Inactivation of critical enzyme
systems responsible for metabolic
activities [CPHEEO, 1999]. Type,
condition, concentration & distribution of
organism to be destroyed, type &
concentration of disinfectant, chemical &
physical characteristics of water to be
treated, contact time available for
disinfection, Temperature of water also
affect the efficiency of disinfection
[CPHEEO, 1999].
Chlorination
Chlorine reacts with water to form
hypochlorous acid (HOCl) and
hydrochloric acid (HCl) according to
equation [Bhole, 2001].
Cl2 + H2O HOCl + H+
+ Cl-
This hydrolysis reaction is reversible. The
hypochlorous acid dissociates into
hydrogen ions (H+
) and hypochlorite ions
(OCl-
) according to equation
HOCl H+
+ OCl-
HOCland OCl-
depend on the pH and
temperature. more than 99% of the free
chlorine is HOCl at pH 5 and similarly
more than 99% is OCl–
at pH 10
[Rosalam, 2007]. The HOCl is 80 to 100
times stronger than OCl-
in-term of
disinfecting the pathogens [CPHEEO,
1999].
The organic and inorganic compounds can
be ammonia, nitrite, nitrate, amino acid,
and suspended solids. When hypochlorous
acid reacts with organic compounds, the
disinfections capability of the HOCl
becomes weak and form combine chlorine.
[Rosalam,2007, CPHEEO, 1999].
Cl2 + H2O HOCl +HCl
NH3 + HOCl NH2Cl+H2O
NH2Cl + HOCl NHCl2+ H20
NHCl2 +HOCl NCl3+H20.[Bhole,
2001]
The combine available chlorine possesses
some disinfecting properties though to a
lower degree than the free available
chlorine.
Other reactions are [Kumar et al, 2012]
a) Carbon
C + 2Cl2 +2H2O 4HCl + CO2
b) Hydrogen Sulfide
H2S + 4Cl2 + 4H2O H2SO4+ 8HCl
H2S + Cl2 S + H2O

3. c) Methane
CH4 + 4Cl2 CCl4 + 4HCl
d) Manganese
MnSO4 + Cl2 + 4NaOH MnO2 +
2NaCl + Na2SO4+ 2H2O
MATERIALS AND METHODS
The DPD method was used for the
determination of chlorinated compounds
such as free chlorine, total chlorine,
monochloramine, chlorine dioxide in
potable water. The DPD method is
applicable to natural and treated waters at
concentrations from 0.2- 4 mg/L [Standard
methods, 1995].
Apparatus:
1) (HACH) DR 2400 spectrophotometer
and distilled water throughout the
experimental work.
2) All glassware used werechlorine
demand free glassware.
3) Pipettes for 0.1ml, 1ml and 10 ml
capacity and conical flasks.
4) Reagent bottles brown amber glassware
for 350ml, 500ml & 1000ml capacity.
5) Analytical balance GF series GF 300,
wensar make pH meter.
Reagents preparation:
Separate glassware was used for the
preparation of reagents, so to avoid
interferencesand the reagents were stored
in the brown amber bottle to maintain the
strength. All chemicals were of reagent
grade and deionised water was used
throughout.Phosphate buffer solution was
prepared by dissolving 24 g anhydrous
disodium hydrogen phosphate, Na2HPO4,
and 46 g anhydrous potassium dihydrogen
phosphate KH2PO4, in distilled water and
adding 800 mg disodium
ethylenediaminetetraacetate
dehydrate(EDTA)in 100 mL distilled
water. These two solutions combined and
diluted to 1 litre with distilled water. The
pH of phosphate buffer was maintained to
6.2-6.5.[Standard methods, 1995].
Mercuric chloride (HgCl2) was omitted
due to environmental considerations even
though it has been shown that its presence
can suppress interfering reactions
(Carlsson et al, 1998).
The DPD reagent was prepared by
dissolving 1.1 g DPD Sulphate in 1000 ml
H2O with 200 mg EDTA and (1+3)
H2SO4to maintain the pHof two. Sulphuric
acid solution (1 + 3) was prepared by
slowly adding 10 ml of H2SO4 (sp. gr.
1.84) to 30 ml of distilled water [Standard
methods, 1995].Like the (1+5) H2SO4 was
also prepared. The Ferrous ammonium
sulphate (FAS) of normality 0.00282 was
prepared by dissolving 1.106 gm. Fe
(NH4)2. (SO4)2.6H2O to 1 ml (1+3 H2SO4)
and make to 1 lit and standardise by as per
standard method. It is required as a check
on any absorption of potassium
permanganate by distilled water while
preparing the standards for calibration of
spectrophotometer. The Sodium arsenite
solution was prepared by dissolving 5.0 g
NaAsO2 in distilled water and diluted to
1L it is required to find the interference of
Manganese in water [Standard methods,
1995]. The 10% glycine solution which is
necessary for determination of chlorine
dioxide is prepared. Barium di -
phymylamine indicator (10%) was
prepared as it is required for the checking
of normality of ferrous ammonium
sulphate and 85% conc. phosphoric acid
was also used to check normality of FAS.
Stock Potassium Permanganate Solution
was prepared by placing 0.891 g KMnO4
in a volumetric flask and diluted to 1 L.
This stock potassium permanganate
solution was used for the calibration of
spectrophotometer. The HACH 2400
spectrophotometer was used for
detection.as it has advantages as
Wavelength range 400- 680 nm, automatic
wavelength selection, photometric
resolution as 0.001 absorbance, 0.1%
transmission and touch screen display with

4. read out modes transmission, absorbance,
and concentration. The wavelength was
used for this methods is 515 nm [Standard
method, 1995].
Calibration of Spectrophotometer:
Figure 1: Calibration graph for DPD
method.
The calibration of spectrophotometer is
done by the use of potassium
permanganate solution.
Potassium permanganate solution (0.891
g/l) - This solution was made by adding
0.891 g of potassium permanganate to a
1000 ml volumetric flask. 1 ml of this
solution is equivalent to 1 milligram of
chlorine, i.e. 1000 mg/l as chlorine
[Standard method, 1995].
Potassium permanganate solution (0.0891
g/l) - This solution was made by adding 10
ml from above made stock solution to 100
ml distilled water. This solution is equal to
100 mg/l as chlorine.
The standards for chlorine are prepared as
per the following details as they are made
from the ranges of 0 to 2 mg/l
concentration-
Adding the 1 ml from (0.0891g/l) solution
to 100 ml distilled water. This is equal to 1
mg/l as chlorine equivalent. Then the
colour was developed by first placing 5 ml
phosphate buffer and DPD indicator to the
flask and adding the above prepared 100
ml sample in the flask [Standard methods,
1995]. Like this the chlorine standards are
prepared for equivalent range from 0.05
mg/l to 2 mg/l. Then the calibration curve
is prepared by using the standards. The
standards made are added to 10 ml sample
for appropriate to spectrophotometer cell
holder. Then the calibration graph is set to
the spectrophotometer for the detection of
parameters.
Sample collection:
The samples were collected randomly
from the various areas of Mumbai city
from greater Mumbai Municipal
Corporation area. Sampling was done as
per the standard sampling procedure
[CPHEEO, 1999]. The brown amber 350
ml glass sampling bottles were used.The
samples were collected from the
residential area, commercial areas and
public places as railwaystation platforms
as from drinking water fountain. The
sample no.1 was collected form residential
areas, sample no.2 was collected from
commercial areas and sample no 3 was
drawn from the public places (railway
stations).
Sample analysis:
The analysis procedure was followed as
per the standard DPD method. The volume
of sample was taken as 10 ml which is
appropriate to the spectrophotometer cell
holder. The free chlorine was determined
by the first placing the 0.5ml phosphate
buffer, DPD indicator and 10 ml potable
water sample to the cell. The concentration
was determined against blank as no
addition of reagents. The total chlorine as
it includes the free and combine chlorine
was determined by the adding 0.5 ml
phosphate buffer, DPD indicator, 1mg
potassium iodide crystals and 10 ml
potable water sample. The free chlorine
will not react in presence of the potassium
iodide. Therefore immediately the colour
was measured for the free chlorine. The

5. two minutes time period was given for the
development of the colour for total
chlorine analysis. The phosphate buffer pH
was maintained to the 6.2-6.5 as the
chlorine is more effective within this range
of pH.In this DPD method after addition of
potassium iodide to the sample the
chlorine and chloramines are liberate
iodine from the potassium iodide. The
colour of the solution was changed and the
difference in colour or intensity of colour
was determined by spectrophotometer.
The most common interference for the
determination of free and total chlorine
was manganese. The determination of
manganese as an interfering agent was
carried out by using sodium arsenite
[Standard method, 1995]. The one mg of
potassium iodide KI was added to the 100
ml free chlorine concentration to
determine the concentration of
monochloramine in potable water sample.
Chlorine dioxide was measure by adding
the glycine reagent to the 10 ml potable
water sample. The aminoacetic acid
removes the interference of chlorine from
the determination of chlorine dioxide and
after adding the 0.5 ml buffer and DPD
indicator. The intensity of colour was
measured by spectrometer.it is carried out
at 515nm wavelength.
RESULTS AND DISCUSSION:
The free chlorine concentration for the
potable water samples for different
locations of Mumbai are as follow
Table 1: Free chlorine concentration
Sampling location 1 2 3
CST 0.05 0.05 0.05
Masjid Bunder 0.09 0.10 0.07
Sandhrust Road 0.11 0.11 0.11
Byculla 0.11 0.11 0.12
Curry road 0.10 0.10 0.10
Matunga 0.13 0.13 0.13
Sion 0.15 0.15 0.16
Vidyavihar 0.15 0.16 0.16
Ghatkopar 0.16 0.17 0.17
Kanjurmarg 0.18 0.18 0.20
Bhandup 0.20 0.21 0.21
Nahur 0.19 0.19 0.21
Mulund 0.20 0.19 0.19
Charchgate 0.07 0.08 0.07
Marine lines 0.08 0.08 0.08
Charni road 0.08 0.10 0.08
Grant road 0.09 0.10 0.10
The Total chlorine concentration for the
potable water samples for different
locations of Mumbai are as follow:
Table 2: Total chlorine concentration
for different areas of Mumbai
Sampling location 1 2 3
CST 0.48 0.50 0.53
Masjid Bunder 0.45 0.45 0.44
Sandhrust road 0.51 0.51 0.53
Byculla 0.45 0.47 0.48
Curry road 0.67 0.68 0.68
Matunga 0.44 0.44 0.43
Sion 0.48 0.47 0.47
Vidyavihar 0.48 0.53 0.56
Ghatkopar 0.55 0.42 0.44
Kanjurmarg 0.45 0.51 0.45
Bhandup 0.40 0.42 0.42
Nahur 0.44 0.45 0.44
Mulund 0.42 0.43 0.51
Charchgate 0.33 0.32 0.36
Marine lines 0.35 0.35 0.36
Charni road 0.38 0.39 0.43
Grant road 0.44 0.50 0.43
The Monochloramine concentration for the
potable water samples for different
locations of Mumbai are as follow
Table 3: Monochloramine concentration
for different areas of Mumbai
Sampling location 1 2 3
CST 0.10 0.11 0.11
Masjid Bunder 0.08 0.08 0.09
Sandhrust road 0.09 0.09 0.10
Byculla 0.07 0.09 0.08
Curry road 0.12 0.12 0.13
Matunga 0.07 0.06 0.08
Sion 0.07 0.09 0.10
Vidyavihar 0.11 0.10 0.11

6. Ghatkopar 0.07 0.09 0.08
Kanjurmarg 0.03 0.06 0.04
Bhandup 0.02 0.02 0.03
Nahur 0.03 0.03 0.03
Mulund 0.02 0.03 0.08
Charchgate 0.04 0.03 0.04
Marine lines 0.04 0.04 0.04
Charni road 0.02 0.03 0.05
Grant road 0.07 0.08 0.07
The water is supplied to the Mumbai is
from the Bhandup water treatment plant.
The capacity of Bhandup water treatment
plant is about 1950 MLD. As from the
above free chlorine concentration results it
is observed that the free chlorine
concentration is go on continuously
decreasing as the water passes through
water treatment plant to the distribution
system. The chlorine concentration is
higher in the Bhandup, Mulund,
Kanjurmarg area and after it is go on
decreasing up to CST Mumbai.
Water supply to Mumbai comes from
Bhandup water treatment plant(WTP). The
Bhandup water treatment plant(WTP) is
using chlorine for disinfection, but the
water is conveyed from the Bhandup
treatment plant to the whole Mumbai
areavia drinking water distribution
network, the water supply pipelines in
Mumbai are very old age and there are
leakages in the water supply pipelines and
are increasing day by day[Hindustan times,
2013] so, there are chances of leakages in
the water distribution system which causes
the contamination of organic matter
through it and also due to the anaerobic
decomposition in the distribution system
chances of ammonia formation are there
Hence chances of formation of
Monochloramines in the water cannot be
ignored.
Table 4: Chlorine dioxide concentration
for different areas of Mumbai
Sampling location 1 2 3
CST 0.04 0.05 0.04
Masjid Bunder 0.06 0.05 0.06
Sandhrust road 0.03 0.04 0.06
Byculla 0.05 0.05 0.06
Curry road 0.03 0.04 0.06
Matunga 0.04 0.05 0.05
Sion 0.06 0.05 0.06
Vidyavihar 0.06 0.05 0.04
Ghatkopar 0.04 0.06 0.03
Kanjurmarg 0.06 0.03 0.06
Bhandup 0.06 0.06 0.06
Nahur 0.03 0.06 0.04
Mulund 0.03 0.06 0.06
Charchgate 0.04 0.06 0.04
Marine lines 0.06 0.03 0.05
Charni road 0.06 0.06 0.03
Grant road 0.04 0.04 0.04
VALIDATION OF RESULTS:
Performance comparison:
For potable water sample test were
conducted using the HACH reagents kit
and prepared regents, the following results
were obtained.
Table 3: Performance comparison of
HACH vs. Prepared reagents
Parameter Concentra
tion as per
HACH
reagents
(mg/l)
Concentrati
on as per
Prepared
reagents
(mg/l)
Free Chlorine 0.10 0.16
Total Chlorine 0.40 0.47
Monochloramine 0.02 0.09
Chlorine Dioixide 0.00 0.06
Overall, the results obtained with the
prepared reagents with the prepared
reagents are comparable with those
obtained from the HACH reagents.
However, the slight difference between the
results occurs due to the presence of
interfering agents which are taken care of
by HACH reagents. However, even with
the presence of interferences, the prepared
reagents can be used for obtaining a rough
about the presence and concentration of

7. the selected parameters for the potable
water samples.
Cost comparison for prepared and HACH
reagents:
Table 4.8 Cost comparison HACH
reagents Vs. Prepared reagents.
(Cost of analysis per sample)
Parameter HACH
Reagents
(Rs.)
Prepared
reagents
(Rs.)
Free Chlorine 21/- 1.20/-
Total Chlorine 21/- 1.30/-
Monochloramine 104/- 1.30/-
Chlorine Dioixide 35/- 1.50/-
The above table shows that a reasonable
accuracy of the results with the great
saving in cost. However it is very
important that periodic calibration of the
prepared reagents is important for
accuracy of result. Hence, laboratory
results are acceptable.
CONCLUSION:
Chlorine compounds or disinfection by-
products in all the Mumbai potable water
samples collected from the different
locations randomly shows that levels less
than the Central Public Health and
Environmental Engineering Organisation
(CPHEEO), World health
organisation(WHO) and US
Environmental protection agency
(USEPA) standards. The amount of free
chlorine reduces as the distance from
Bhandup water treatment plant increases.
So, there will no health risk to human due
to potable water and disinfection by-
products (DBPs) in sampling locations.
The study also revels on comparing the
results for the above disinfection by-
products (DBPs) determinations that the
laboratory chemicals as given by the
standard methods are fairly accurate. The
cost of sample analysis is much lower.
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