Ground water contamination: Effect of sanitation system in rural India

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Posted on March 30, 2013 - 15:17

Of late there is lot of awareness among rural population regarding the usage of toilets and related hygienic conditions. Government agencies and NGO’s are participating in a big way in this programme. Government of India initiated a program “Total Sanitation Campaign” (TSC) with the objective of eradicating the practice of Open Defecation by 2012. This programme has become part of rural water supply schemes for the past 5-10 years. Water supply schemes providing safe drinking water to villages and towns had priority in earlier schemes. But now, water and sanitation schemes are being contemplated simultaneously.

The objective of these schemes is to maintain adequate sanitation and provide safe drinking water to rural population. There appears to be a lot of progress achieved in sanitation and water programmes. In spite of commendable progress achieved in these schemes, surveys have revealed that even after a massive programme of toilets construction, there appears to be little change in the overall health status of public. As per the surveys conducted in Maharashtra, from 1996-97 to 1999-2000, more than 16 lac Latrines were constructed, but still there is very little improvement in the health sector, where the number of water borne diseases do not show any significant reduction in the subsequent years.

 Table 1: Status of water borne diseases in Maharashtra

Disease

1999-2000 (Attacks)

2000-2001 (Attacks0

2001-2002 (Attacks)

Gastroenteritis

65,067

32,479

67,295

Diarrhoea

10,23,194

11,46,395

11,04,841

Inf. Hepatitis

16,159

13,343

12,066

Typhoid

13,079

15,438

13,320

Cholera

348

1,043

1,326

Source: Drinking water and sanitation in Rural Maharashtra: A review of policy Initiatives By Shree Keshab Das

 Despite spending crores of rupees to contain water pollution, water samples are continuously failing to meet the prescribed quality standards. Same situation and conditions exist in other states.

 Probable Reasons for Poor Groundwater Quality

  • The most common water quality problem in rural water supply is bacterial contamination from septic tanks which are often used in rural areas.
  • Pollutants also move into groundwater through
  • Macro pores
  • Root system
  • Animal burrows
  • Abandoned wells.
  • Closer the contaminant source is to the water well, more the chances of pollution.
  • Greater the distance between source of contamination and groundwater abstraction structure, the more likely that natural processes like Oxidation, Biological degradation and Absorption reduce the impacts of contamination.
  • Septic tanks that do not have sewage treatment systems.
  • Arrangements for safe disposal of solid waste, rain water, and domestic liquid are lacking in many villages.
  • Effluent (overflow and leakage) from septic tank can percolate (seep) down to the groundwater.

 The risk of contamination is greater in the areas where shallow groundwater conditions exist. The Central Groundwater Board maintains National Network Observation Well data  Water Level Information gis2.nic.in/cgwb/Gemsdata.aspx). As per this data, it is observed that in Andhra Pradesh state, as against 693 number of observation wells (generally one observation well represents one mandal having average of around 20 villages in Andhra Pradesh; in other states, Taluks and Blocks are common where more than one observation is established to monitor the seasonal water levels), 113 number of wells recorded 0-2 meter water level below ground level during rainy season. District wise details of shallow groundwater conditions (0-2m bgl) are given below.

 Table 2: Shallow Groundwater Conditions

SL.NO

Name of District

No of observation wells taken for analysis

No of wells in the range of 0-2 m water level during rainy season

Probable reasons for near Ground level water table conditions during rainy season.

1.

Srikakulam

50

9 no obs wells

Groundwater exploitation is low,hilly area more

2.

Vizianagaram

24

10 nos

                  ---Do----

3.

Visakhapatnam

46

3

Half of the area is tribal, other half well developed in irrigation.

4.

East Godavari

74

22

Delta area, along the River Godavari and Canal command area.

5.

West Godavari

62

15

Along the River Godavari with canal net work.

6.

Krishna

67

13

More delta area.

7

Guntur

95

13

Along River Krishna and canal net work.

8.

Prakasam

34

3

Sea coast  and valley fill areas

9.

Nellore

68

5

Sea coast  and valley fill areas

10.

Chittoor

96

1

Valley fill area

11.

Kadapa

77

1

Foot hill zone and  valley fill area

12.

Anantpur

26

2

Valley fills area.

13.

Kurnool

41

5

 Eastern portion dotted with hills.valley fill

area and foot hill zone.

14

Hyderabad

34

5

 Near surface  water bodies.

15.

Rangareddy

95

7

------------do----------------

16.

Medak

24

4

Near surface water bodies and foot hill zone

17.

Mahabubnagar

32

8

----------------do-------------------------

18.

Nalgonda

70

5

----------------do-------------------------

19.

Nizamabad

28

5

----------------do------------------------

20.

Warangal

94

11

 Eastern portion hilly.valley fill and foot hill

Zones.

21.

Karimnagar

44

7

Soft rock area and hilly terrain in Manthani and Mahadevpur areas. Canal command and

Foot hill zones.

22.

Khammam

50

8

Major sedimentary rock terrain. River Godavari is flowing. Tribal area is more. Valley fill, foot hill zones and along major streams.

23.

Adilabad

81

14

Tribal and hilly area more. Along the river, foot hill zone and valley fill areas.

Data based on 2008 and 2009 calendar years.

In the above data, observation wells where the depth to water level during rainy season is 0-2m, are susceptible to groundwater contamination from septic tanks. During rainy season, there is a possibility of mixing of groundwater, drainage water and effluents from septic latrines. In such conditions, water borne diseases affect the villagers who depend on groundwater for drinking water purpose. Water-borne diseases affect the occasional guests, who visit their native villages after spending long time in cities where safe drinking water is available, and floating population. Contaminated water affects the children, old people and occasional guests more when compared to the others. Probably local residents develop immunity to accept contaminated water.

Similarly, in other states also (source: Groundwater Scenario of India 2009-2010 CGWB year book), 4% to 75% of observation wells recorded 0-2m depth to water level during rainy season. The highest percentage is in Assam and lowest percentage in Delhi. Karnataka state recorded 20% of observation wells, TamilNadu 5% observation wells; Maharashtra 31% of observation wells recorded the depth to water level from zero to 2m below ground level during rainy season. The near ground level water table  record particularly  during rainy season in Delta areas, along the major Rivers, Canal and Tank command areas, Buried pediments, Valley fill areas, Tribal and Forest areas where groundwater exploitation is low to negligible. In absence of underground drainage system, groundwater contamination is possible due to numerous types of human activities such as

1. Residential

2. Municipal

3. Commercial

4. Industrial and

5. Agricultural activities.

Water Related Diseases Due to Microbial Contamination

Water-borne diseases are Viral, Bacterial, Protozoal and Thread worm

  •  Viral diseases are infective hepatitis and polio-myclitis
  • Bacterial diseases are diarrhoea, dysentery, cholera and typhoid
  • Protozoa diseases are amoebiasis, giardiasis, helminthic i.e round worm and thread worm.
  • Mathemoglobinemia or blue baby syndrome, an illness affecting infants, can be caused by drinking water that is high in Nitrate.

 

Microbial drinking water quality test is very important at the Source and Point of abstraction. Household containers also spoil the water quality. Monitoring of drinking water catchment, point of abstraction and container water quality also should be carried out to find out where the contamination of groundwater took place and level of pollution at different places i.e at source, point of abstraction and in water containers.

 Bacterial indicators E-coli, Thermo tolerant coli presence in drinking water indicates contamination. E-coli are derived mostly from human and animal faeces. Thermo tolerant coli grows at 44 degree centigrade. Faecal Streptococci is an indicator of faecal pollution, and survive longer water environment than E-coli.

 REMEDIAL MEASURES

  1. If the groundwater contamination is very high, water supply must be abandoned as a source of drinking water.
  2. In other cases, groundwater can be treated and supplied to public.
  3. Prevent the contaminated water to migrate.
  4. Pumping the water, treating it and returning it to the aquifer.
  5. Allowing the contaminant to reduce naturally following the implementation of appropriate source control.
  6. In the villages where safe drinking water is provided under Rural water supply schemes, it is essential that water pipes should not go through sewage or should not be submerged in sewage locations. Since in the villages, sewage channels are open, there is the possibility of sewage mixing with pipe water.
  7. Though it is a monumental task, we wish someday underground drainage system should come to all the rural areas which reduce the contamination of groundwater from organic particles.
  8. In rural areas, at present, rural water supply schemes are being implemented under Water and Sanitation. The objective of the scheme is to provide safe drinking water providing Tap connections and ensure all the households construct latrines so as to avoid open defecation. But large number of villages still depends on Dugwell or Borewell with hand pump for drinking water. Also, open defecation is practiced in many villages and few villages adopt septic latrines. There is big drive in the rural areas to have latrines in each house. This practice also leads to groundwater contamination.
  9. Efforts should be made to reduce the water contamination by adopting better methods of sanitation. Disposal of drainage water, sewage disposal, distance criteria maintained between sanitation and drinking water source and abstraction. Periodic monitoring of microbial groundwater quality and sanitation risk inspection data for water source (Dugwells and Borewells) questionnaire as prescribed by WHO in their water quality reports