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Dhamaka Latrine

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    Study and evaluation of Dhamaka/ Kui Latrine

    ( a variant of bore hole latrine)

    prevalent in some districts in Rajasthan

    by

    Dr. S.V. Mapuskar

    Appa Patwardhan safai W Paryawaran Tantraniketan,

    Dehu village, Tal. Haveli, Dist. Pune, Maharashtra 412 109.INDIA

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    1. Objective :-In Rajasthan State of India, predominantly in two districts, Sriganganagar and

    Hanumangarh districts, a design of latrine locally termed, Dhamaka latrine or KuiLatrine is prevalent and in use for the last about 30 years. Doubts had been repeatedly

    raised whether, (i) this design can be considered as a sanitary latrine and (ii) its

    suitability for the area.

    Therfore, it was planned to undertake a study, as regards the technical

    admissibility of Dhamaka toilets as sanitary toilets and its appropriateness as regards

    local requirements. Further, in case the design was not considered sanitary, whether an

    alternative design could be suggested? If alternative designs were not found to be

    appropriate, whether any modifications would be required to convert the toilets into

    sanitary toilets, if these were not considered sanitary.

    The study was undertaken during March 2007 and April 2007.

    2. Methodology used for study:-

    Prior to field visits, which were undertaken from 27th

    to 29th

    March, the basic data

    as regards hydrogeological conditions in the area and the data about the present drinking

    water sources, surface water sources as well as ground water sources were collected. The

    basic design concept of Dhamaka latrine was also obtained.

    The study team visited Sriganganagar and Hanumangarh districts from 27th

    to 29th

    March 2007. The team held detailed discussions with Rajasthan Government officialswhich included engineers and staff members from state water supply and sanitation

    mission Government of Rajasthan, engineers of PHED in two Districts and other staff

    members who are responsible for TSC and drinking water supply, in these two districts.

    The team also had detailed discussions with hydrogeologist and chemist of public

    health laboratories in the districts as regards hydrogeological data and the water qualitymonitoring from various drinking water supply schemes, from surface water sources aswell as ground water sources. The data as regards microbiological and nitrate levels in

    ground water for the last 5 years was reviewed. The team visited 5 villages in two

    districts. The villages were selected on the basis of source of drinking water (that is,

    villages fed by canal water and villages fed by ground water as well). In addition,samples were collected from visited villages for bacteriological examinations as well as

    the nitrate level estimates. The team also interacted with community to discuss their

    perception about the use of these toilets, evolution of the use of toilets in the area,

    knowledge on other options of the toilet, convenience and comfort issues.

    3. Brief review of the designThe Dhamaka toilet design technologically is a type ofborehole latrine. Design is

    locally termed Dhamaka or Dhamakedar because of the noise produced when the

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    night soil and water strike the bottom of the pit, which is any where between 25 to 40 ft

    deep. A pit of between 2 to 3 ft diameter is manually dug in the soil to the depth of 25 to40 ft. Digging manually is possible because the soil is made up of dense clay, which

    does not collapse. Hole in the clay layer is dug so as to reach the sand layer below that.Digging is stopped after removing a few feet of pervious sand layer, which the

    experienced digger identifies from the fact that the walls of the pit in sand layer start

    cracking and collapsing. No lining of any kind is used as the clay layer does not crack or

    collapse even after several years. The pit or borehole is covered with a stone slab whichis available locally and has a squatting hole of 4 to 6 inches in diameter. At some places

    concrete slabs are also provided as a squatting platform. Generally no pan or trap is

    provided in the squatting plate. The squatting plate has simply a drop hole.

    Dhamaka Latrine

    A G shaped super structure as indicated in drawing is constructed around the

    squatting plate with bricks or mud blocks. Height of wall may be around 4 to 6 feet. In

    most of the cases, roof for the superstructure is not provided.

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    This pit can be used by a single family for about 15 to 20 years. When the pit gets

    filled up, it is closed and a new pit is dug at an adjacent suitable place for future use andit is covered with the same slab and a super structure. Old pit is closed with soil and

    abandoned.

    4. Villages Visitedi. Masruwala village, Hanumangarh, (water sourceground + canal water)ii. Pucca Saharana, Hanumangarh, (water source-canal water)iii. Village 3Y, Sriganganagar (water source-ground +canal water)iv. Village 3G Kaliyan, Sriganganagar (water source-ground + canal water)v. Village 4 ML, Sriganganagar (water source canal water)

    5 Salient features noted during field visit as regards the latrine use

    In Masruwala Village, some toilets were visited. All the latrines in the villageare Dhamaka type. Depth of toilet pits varied between 30ft. to 40ft. Bore wells were

    found to be within a distance of 10-20 ft from toilets. Toilet seats smelled badly. Plenty

    of hovering flies were noticed in most of the toilets. For bore wells, it was told that water

    table is at 27 M (about 80ft) and depth of water column in the wells about 6-7 meters.Some toilets in village have water seal traps and pans fitted for the toilet seat. Some have

    latrine pans without water seal trap. 50 % houses have own bore wells. Occasional

    incidence of infective hepatitis was reported. In one visited house, owner wanted the trap

    to be fitted but mason did not fit it.

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    In Pucca Saharana Village, again toilets and tube wellswere visited. All latrines

    in village are Dhamaka type. Depth of toilet pits varied from 30 to 40 ft. Toilet seatssmelled badly. Plenty of flies were noticed in toilet seat enclosures. In one house, for

    waste water management also Kui was dug. In many places, waste water was collectedin small shallow pits and twice a day, accumulated water was sprinkled on the street

    where it would evaporate naturally. The shallow pits could not soak water. In this

    village one dry dug well of about 100 ft. depth was seen. Very adjacent to the well, a

    large water tank orjohadwas present. But water from tank was not percolating to thewell indicating the impervious nature of the floor of the tank.

    On 29.03.07, a meeting with the Collector, Sriganganagar was arranged. During

    discussion it was revealed that, govt. has set up a norm that in villages with less than

    4000 population house hold water connections are not given. Therefore, in these villages

    many households depend on their own private bore wells.

    In Village 3 Y also all latrines in the village are Dhamaka type. In one house, asan exception, vent pipe was fixed on pit, the toilet seat being offset with pan but no trap.The latrine was clean and without flies. On enquiry, it was informed that this was

    suggested by the mason. This village has a dug well where water level was about 40ft

    deep. This water was found to be polluted during routine monitoring by PHED. Private

    bore wells are in use in the village.

    In Village 3 G (Kaliyan) Dhamaka latrines were similar type. Here, due to

    nearness to Sriganganagar town, tendency towards construction of septic tank toilet isincreasing. Effluent from these septic tanks is let out in open surface drain. The effluent

    from these drains passes out to ajohadformed by waste water from the village. The soildoesnt absorb sullage from the village. The bore well adjacent to thisjohadwas foundto be heavily polluted as reported during the monitoring by PHED. Thus, septic tanks

    might become problematic for the village.

    In Village 4 ML, households have similar type of Dhamaka toilets. Here in a

    school, latrine with pan, trap, chamber and two Kuis, similar to twin pit latrine wereconstructed but was not brought into use because of apprehension and non availability oftap water connection.

    In this village many houses had Dhamaka toilets with latrine pan, trap and

    occasionally vent pipe.

    The percentage coverage with Dhamaka Latrines is very high. Any where

    between 70% to 90% households have such latrines in some villages. Pit for the toilet is

    dug manually by charging a labour rate at about 6 to 8 Rupees per foot of depth. Hence itis affordable for most of the families.

    During the field visit, it was noticed that in most of the cases the urine was getting

    into the drop hole in very haphazard manner as the channel for the passage of urine was

    very haphazard. Further, the obnoxious odour pervaded the toilet seat enclosure. The

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    smell was reduced to some extent because of the absence of roof. The odour was very

    marked where the roof was provided. Large amount of flies and mosquitoes were noticedin the toilets. The drop hole did not have any cover when the latrine was not in use.

    Squatting in such a toilet for more time would be very repulsive.

    It was also noticed that in many places adult males in the family prefer to go out

    for open defaecation. In such cases, the latrines were predominantly used by women.

    Hence, the head of the family was probably not interested in spending money forimproving the quality of the latrine.

    In many places, bore wells for drinking water purposes were found to be adjacent

    to the latrines. In some places the distance was hardly 10 ft from the toilet.

    We had also discussions with some NGO representatives. It was felt that they did

    not have clear ideas about toilet design requirements and about various latrinetechnologies.

    6.Status for drinking water supply in these districts.

    In these two districts, as revealed in Rajasthan govt. report, in Sriganganagar

    district, out of 2830 villages, 515 (hand pumps) villages have government drinking water

    supply schemes using ground water as a source. In Hanumangarh, out of 1773 villages,

    470 (hand pumps) villages have govt. drinking water supply schemes based on ground

    water as a source. Thus, nearly 25 % villages in these two districts are using groundwater for drinking purposes.

    In the villages which were visited, many households had their personal bore wells.

    PHED does not have a record of such bore wells. Further, it was revealed that

    government does not provide household water tap connections in villages having less

    than 4000 population. In these villages only public stand posts are provided. Therefore

    well to do people who can afford to dig their own tube wells have their own tube wells.Thus, percentage of population using ground water is probably much more than 25%.

    Therefore, possibility of ground water contamination due to on site sanitation,

    emerges as an important issue.

    7. Appropriate latrine design for on site sanitation in rural area

    In assessing the appropriateness of the latrine design, following points will have

    to be considered.

    A) Transfer of microbial contamination via the surface level construction of toilet

    seat etc.

    a) surface soil should not get contaminated

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    b) no contamination of surface waterc) no handling of fresh excretad) excreta should not be accessible to flies and animalse) freedom from odourf) aesthetically pleasantg) should be simple and inexpensive

    B) Risk to drinking water supplya) microbial contamination of ground waterb) chemical, predominantly nitrate contamination of ground water

    Points related to A above are mainly related to proper toilet seat and

    superstructure. These issues become significant, due to possibility of microbe spread via

    vectors and unhygienic behavior of user.

    Points related to B above are mainly related to what happens to nightsoil and theemergent contaminants from it below the ground, from where the contamination of

    ground water may be possible.

    The microbial contamination in ground water would depend on

    porosity and permeability of subsoil surface and the geohydrological environment viscinity of ground water aquifer from the absorbing surface of the pit.The chemical contamination, predominantly due to nitrate leaching would depend on,

    the nature of subsurface and the geohydrological environment type of on site sanitation system which would determine the proportion of nitrate

    leaching

    viscinity of on site sanitation facility to ground water aquifer, vertically as well aslaterally.

    In pit latrines of any design, ablution wash water and digestive process water issupposed to be absorbed / leached in soil.

    While this process of absorption / leaching is taking place in the soil, the

    contamination attenuationprocesses, which control the numbers and concentrations of

    the contaminants, is the key to understanding the risk from on site sanitation

    technologies.

    The key processes in the attenuation of microbial contaminants could be

    die off dilution and dispersion adsorption and filtration

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    In these processes travel time is an important factor. The travel time from source

    to ground water aquifer of around 50 days minimizes the risk. All these will depend ongeological characteristics of soil layers.

    The processes in the attenuation of chemical contaminants like nitrates can occur

    where through plantations biological uptake occurs. Under aerobic conditions nitrates are

    mobile. However, in anaerobic conditions there is very little attenuation of nitrates. In

    anaerobic conditions, where nitrate load is high and is derived from large number of pointsources, over an extensive area, the nitrates slowly can migrate to ground water. Once

    high levels of nitrates are present in the ground water, concentrations will not decrease

    rapidly. Thus, here also the geological structure of the soil layers remains an important

    factor.

    The liquid part of the waste in a pit latrine that infiltrates into the soil is called the

    hydraulic load. Where hydraulic loads are high and exceed natural attenuation potential,direct contamination of ground water is possible. As stated earlier, travel time of thishydraulic load also is important. This will, besides other factors, depend to a large extenton geological characteristics of subsoil layers.

    8. Comparative evaluationof twin shallow pit latrines and borehole latrine

    Based on these criteria, in India, twin pit latrine with shallow pits, are being

    considered as the most appropriate technology for toilets.

    However, in some specific situations, other technologies, after reviewing pros and

    cons of such technologies, might turn out to be more suitable.

    The available field experiences and literature as regards Bore Hole latrine has

    thrown up some inferences as regards this technology.

    As the bore hole pit is deep, the possibility of ground water aquifer

    contamination, both bacterial and chemical is considerable. From the seat, spread ofinfection via flies is possible hence hygienically it may not be advisable. The presence ofodour is repelling. As the pit is deep, the decomposition of night soil is anaerobic.

    Hence the smell of obnoxious gases like H2S will be present. Due to anaerobic digestion,

    methane is produced during the process. This can escape only through drop hole.

    Instances have been noted in other states, where similar versions of bore hole like designsare in use, that this gas has exploded due to lamp flame or smoking, causing burns to the

    user.

    Therefore twin pit latrines, with shallow pits (and water seal trap for toilet seat),where aerobic digestion takes place, possibility of ground water contamination is

    minimized and hygienically safe and odourless toilet seat is fixed, is considered as an

    appropriate technology in rural areas.

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    However, there may be situations where, due to technical issues, twin pit latrine

    with shallow pits is not feasible. In such cases, other technological options will have tobe considered.

    Keeping these facts in view, Dhamaka toilet design will have to be evaluated.

    In this evaluation, the hydrogeological factors will be very important.

    Further it would be necessary to decide whether alternative designs are possible.

    If that is not possible, what modifications would be necessary to convert it to a sanitary

    toilet?

    9. Geohydrological data for soil

    As seen above, the geological characteristics of soil strata would be an importantcriteria for the suitability of pit latrine, of any design.

    Aquifers transmit water, as well as store water. This is affected by two factors i.

    porosity ii. permeability

    Unconsolidated granular sediments in the soil such as sands, silt, clay etc. contain

    pore space between the grains. The proportion of pore spaces to the total volume of

    sediments is known as porosity. In sand, porosity can extend to above 30 %.

    The water transmitting characteristic is known as its permeability. Well connected

    pore spaces between the grains of sand and gravel increase their permeability. However,clays which have high porosity, but very little connection between the pores because of

    very small grains and compactness, transmit water very poorly, resulting into very low

    permeability.

    Grain sizes of a range of sediment types from Guidelines for Assessing the Risk to

    Groundwater from Onsite sanitation DFID 2001.

    Naturally, in soils with low permeability, the travel time for contaminations will

    increase. The greater the travel tie the greater the opportunity for contaminant

    attenuation.

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    Typical permeability values for various rock types

    Lithology Range of likely

    permeability (m/d)

    Silt 0.01-0.1

    Fine silty sand 0.1-10

    Weathered basement(not fractured) 0.01-10

    Medium sand 10-100

    Gravel 100-1000

    The geological characteristics of the region will naturally have a bearing on the

    technology selection for on site sanitation. The kind of geological layers in the ground

    would be important.

    10. Geohydrological Data for Sriganganagar and Hanumangarh

    While analyzing ground water trends from these districts, as shown in the maps,

    following facts emerge.

    In Sriganganagar and Hanumangarh districts, the geological strata are very

    significant. The soil and the strata up to about 20 to 30 ft (8 to 10 metres) is a layer of

    compact clay and silt with plenty of gypsum. As a result, this layer is having very lowpermeability for water. The travel time for water through this layer may be of several

    months or years.

    The vertical sections show that the top layer comprises of clay or clay + silt from

    fluvial origin in most of the areas of these two districts. The thickness (depth) of this

    layer varies from approx 10 to 20 ft (occasionally wind blown sand forms a thin surface

    layer). This layer is fairly compact and imperious to water.

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    Below this top layer of clay, sand layer is present. For this sand layer, the porosity

    may be even to the extent of 30%. This layer would be very permeable with relativelyless travel time. Hence leaching of water from this layer would be better. This justifies

    the depth of pit in Dhamaka toilet.

    This sand layer is a part of aquifer, as indicated in the maps. Further, the subsoilwater levels, as indicated in map, have been found in both districts to vary between 30ft

    to 120ft. In potable water zone, water levels are nearer the surface.

    In northern region of Sriganganagar District, depth of water level is less than 20

    M in NW region and between 20-40 M in northern and SW region. In northern region,

    nitrate distribution is below 50mg/Lt.

    In Hanumangarh district, the depth of water level is less than 20 M in northernregion and between 20-40 M in central and NW region. In the same region, nitratedistribution is below 50 mg/Lt.

    As far as the evaluation of Dhamaka toilets is concerned, all this geological data

    would be important for foreseeing the ground water contamination effects due to

    generalized use of Dhamaka toilets.

    11. Relevance of this data in technology selection

    These hydrogeological conditions in these two districts (and perhaps in areas ofadjacent districts in Rajasthan, Hariyana and Punjab) become an important consideration

    in selection of on site sanitation technology.

    Although twin pit latrine with shallow pit is a generally accepted technology, in

    these two districts, it would not be appropriate. Water from the shallow pits will not

    leach out because of the clay layer with very low permeability. Hence shallow pit latrineis not likely to function properly in this zone. When leaching of water from the pit isexpected, deeper pit reaching the sand layer where permeability is higher, will be the only

    suitable technology in such situation.

    Septic tank technology also will not be appropriate, because the issue ofmanagement of effluent from septic tank would be problematic due to top clay layer. In

    one village near Sriganganagar, some families had opted for a change over from Kui or

    Dhamaka latrine to septic tank. The effluent from septic tank was let out to surface

    drain. This surface drain ended in a small cess pool like tank resembling johad. The bore well adjacent to this tank showed both microbial and chemical contaminations.

    Therefore it is felt that this kind of changeover from Dhamaka to septic tank should be

    discouraged.

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    The other possible option could be a compost toilet (ecosan). However in this case,

    the operation and maintenance demands very high motivation levels. As such in thesedistricts, these may not prove to be an appropriate technology as a mass measure.

    Under the circumstances, bore hole latrine seems to be a desirable technology for

    this region. It will have to be accepted. However, the risk assessment factors stated

    earlier must be remembered. These risks could be i. from toilet seat and ii from

    contamination of ground water. We have to accept the risk, with clear mandate forincreased level of monitoring and mitigation efforts. In places where shallow pit latrines

    are possible, this design may not be approved.

    While using this technology, some changes are necessary. Dhamaka toilet as it

    stands today cannot be termed as sanitary. However, with some modifications it can be

    very easily converted to a sanitary latrine. The toilet seat component needs modifications

    so as to minimize contaminations from surface of the seat. Further, as stated earlier, avery rigorous monitoring of ground water would be essential.

    12. Modifications in toilet seat portion

    Avoiding microbe spread via toilet seat or drop hole can be avoided if suitable

    modifications are carried out. This can be done by providing latrine pan with water seal

    trap for the toilet seat. Goose neck pans with incorporated traps made out of C.C. mosaic

    material, ceramic or LLDPE plastic moulded pans can be fitted. If the toilet seat is

    placed offset, routine pan and trap with necessary pipeline can be fitted.

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    Alternatively a latrine pan without water seal, accompanied by a vent pipe of

    minimum 100 mm diameter can be provided. In such a case, the vent pipe should reachabove the roof level and the upper end of pipe should be covered by wire gause or net to

    prevent passage of vectors like flies and mosquitoes. This pipe will provide ventilationas envisaged in V.I.P. toilets.

    13. Possibility of ground water contamination

    Possibility of microbial contamination of ground water obtained from tube wellsmust be considered. The leachet from borehole latrine will pass vertically and laterally

    through sand layer for adequate distance for attenuation of this contamination. In tube

    wells as well as dug wells microbial contamination was noticed where multiple latrines

    were present within a distance of few feet from the well. It will be advisable to keep a

    distance of about 50ft between wells and nearest latrine, to allow for attenuation of thecontamination.

    As far as chemical contamination from on site sanitation is concerned nitrate

    contamination is the most important. As per WHO prescribed standards, in potable

    ground water, the nitrate levels should not exceed 50mg/Lt and nitrites at 3mg/Lt. High

    nitrate levels give rise to methaemaglobinaemia. Further, once the nitrate levels increase,

    remedial measures are not possible. It has to be noted that nitrates go on increasing inaquifer very gradually. It is a continuous slow process going on over the years.

    Therefore, chemical contamination of ground water needs to be monitored rigorously.

    In case of Dhamaka toilet, the bore reaches sand layer which is a part of aquifer asindicated in geohydrological maps. Hence, these nitrates are ultimately reaching the

    aquifer.

    From the 5 villages visited by us, from two villages, namely 3Y and 3G, nitratetrends from 2001 to 2007 were available. In 3Y nitrates were 4mg/Lt in 2001 against

    10mg/Lt in 2007. In village 3G nitrates were 35mg/Lt in 2001 as against 45mg/Lt in

    2007. This indicates a definite trend towards rise in nitrates levels. In few more years

    this might reach unacceptable level. Such data from remaining three villages was not

    available.

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    In point 10 water level trends have been discussed. The premonsoon water level

    depths have been indicated as varying between 30ft to 120ft in the aquifers immediately

    underneath the top clay layer. The bore holes in Dhamaka toilets are reaching in thesame aquifer to the depth of 30ft to 40ft. Naturally the vertical separation may be non

    existent in many cases. There, the attenuation of microbial and chemical contamination

    will depend only on lateral separation, increasing travel time marginally.

    Once nitrate levels exceed 50 mg/Lt that source has to be abandoned for drinking

    water purposes.

    Hence, continuous monitoring of these sources for microbial and chemicalcontamination would become very essential. Microbial contaminations can be taken careof by purification processes like chlorination. However, if nitrate levels increase the only

    way is to abandon the source.

    This monitoring will have to be done for private tube wells also, in a planned

    manner.

    14. Observations and comments

    a. In the area specific situation Dhamaka latrine is a suitable design with somemodifications and reservations. Bore hole latrine is generally considered as a less

    desirable option. However, in hydrogeological situation existing in these districts, there

    is no suitable alternative to borehole latrine.

    b. As they exist today, Dhamaka latrine cant be considered as sanitary latrine. Theexisting design needs to be modified. Following modifications are suggested.

    c.Modifications to toilet seat as indicated in point 12 are suggested.d. There are indications that in some tube wells and dug wells microbialcontamination have taken place. Therefore periodical rigorous monitoring, where groundwater from wells (government established or private) is used for drinking, is necessary.

    Public health laboratories in each district can do this.

    e. Similarly continuous monitoring for chemical contamination is necessary. Publichealth laboratories in each district can do this.

    f. Data about private tube wells is not available. Each Gram Panchayat and eachDistrict PHED may maintain this data.

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    g. Private tube wells may also be randomly monitored by microbiological andchemical examination.

    h. Suitably modified Dhamaka latrine may be considered appropriate only in areaswhere top layer of soil consists of clay which is grossly impervious to water. It is not

    desirable in areas with water permeable upper soil strata. Where soil conditions permit

    shallow twin pit latrine is advisable.

    i. PHED, Govt. of Rajasthan can decide on areas where only bore hole latrines aresuitable, based on hydrogeological data, considering that bore hole latrine is a less

    desirable technology to be used only where it is inevitable.

    j. Changeover from Dhamaka to septic tank, in areas with low soil permeability forwater should be actively discouraged by active IEC campaign.

    k. Modifications to existing Dhamaka toilet seat can be encouraged by IEC effortsand possibly by providing incentive from various possible sources.

    l. For new constructions for BPL households, modified Dhamaka should be insistedupon, for disbursement of the incentive.

    m. Rajasthan government, at present, has fixed the norm that in villages with lessthan 4000 population, house hold drinking water connections should not be given from

    village water supply schemes. Due to this rule, the number of private tube wells increaseand the use of ground water for drinking purposes increases, irrespective of the potability

    state of ground water. It may be desirable to change this rule. It will be conducive toimproved health status of the community.

    n. It was felt that grass root level functionaries of NGOs working with governmentfor TSC work were not very conversant with merits and demerits of various on site

    technologies. Orientation and training of such personnel is advisable. This can be done

    even for grass root level personnel of PHED, involved in TSC work.

    o. It may be pointed out that above mentioned measures might only delay the groundwater contamination. These will remain as short term risk management methods. Once

    nitrates increase in ground water, it is permanent. In given soil conditions and the

    necessity for sanitation measures, in long term, ground water is not likely to remain potable. Hence, sanitation and drinking water supply in these regions will have to be

    planed comprehensively by reviewing all technologies with a long term perspective.

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    Acknowledgements:

    I am thankful to Mr Kumar Alok, IAS, WASH officer, Unicef regional office, New

    Delhi, for his initiative and support for this study. I am also thankful to Mr. M. K. M.Joshi, ACE (Rural), PHED from state water supply and sanitation mission, Government

    of Rajasthan for his support during this study. This study was initiated and supported by

    Unicef Area Office, New Delhi. The hydrogeological maps were made available by Mr

    Pankaj Mathur of Unicef Jaipur office from the publications of the Government ofRajasthan. Mr Mathur was also helpful in the field study. I gratefully acknowledge the

    geological drawings and information from Guidelines for Assessing the Risk to

    Groundwater from onsite sanitation by Lawrence AR et al published by DFID in 2001. I

    am also grateful to various officials of the Government of Rajasthan, who very kindly

    provided all the necessary information and support during the study.