River Water Quality

Overall the fresh water in India is slightly alkaline (pH generally more than 7) and contains a lots of HCO3- and Ca2+. Table shows the average chemical composition of many rivers in India. All waters contain some dissolved minerals (dissolved solids) and have any freshwater can be considered as "mineral" water. Generally there are more dissolved solids in peninsular rivers compared to the Himalayan river system.

 

Average chemical composition of major rivers in India

 

River

Discharge

HCO3-

Cl-

SO42-

SiO2

Ca++

Mg++

Na+

K+

TDS

Cauvery

21000

135

20

13

23

21

9

43

4

272

Krishna

29000

178

38

49

24

29

8

30

2

360

Godavari

92000

105

17

8

10

22

5

12

3

181

Mahanadi

66000

122

23

3

17

24

13

14

8

224

Narmada

40750

225

20

5

9

14

20

27

2

322

Tapti

17000

150

65

1

16

19

22

48

3

322

Indus

210000

64

9

15

5

27

1

1

2

122

Brahmaputra

510000

56

11

4

7

14

5

7

3

 

Ganges

468700

128

10

11

18

25

8

11

3

214

Indian rivers

1700000

74

15

13

7

30

7

12

3

159

There are no major differences between the rivers but for any one river, the chemical composition may vary at different times and at different places since water quality is highly susceptible to spatial and temporal variability. Since rivers and growth of various civilisations are inter linked, the density of population generally is very high along almost all rivers expert for the upper reaches of Brahmaputra that are sparsely populated. In fact the Bengal basin comprising of the lower reaches of the Ganges-Brahmaputra system is the most densely populated region in the world.