The Impact of Pit Latrines on Groundwater Quality

  • F H Mughal
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The Impact of Pit Latrines on Groundwater Quality

I recently came across with an interesting publication: Pit Latrines and Their Impacts on Groundwater Quality: A Systematic Review, Jay P. Graham and Matthew L. Polizzotto, dx.doi.org/10.1289/ehp.1206028 , ehp.niehs.nih.gov/1206028/ (Ms. Elizabeth: it says open access; so I believe no violation of copyrights laws – Please check at your end. Have I provided the link correctly?).

In the rural areas of Sindh province (Pakistan), pit latrines are used extensively by the rural people. There are no yardsticks as regards their siting with respect to the location of wells. There are some reports of groundwater contamination, due to the close proximity of pit latrines. While, the distance between the pit latrines and the location of wells depends on the nature and type of soil between the pit latrines and the wells, I think there are some regulations, according to which the minimum distance between the pit latrines and the wells should be 100 meters.

It would be helpful, if someone could highlight the siting regulations – location of pit latrines with respect to wells; and also highlight some case studies. Thanks

F H Mughal

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  • JKMakowka
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Re: The Impact of Pit Latrines on Groundwater Quality

Working download link:
www.sswm.info/library/7411

Microbiologist & emergency WASH specialist
Visit the new WASH Q&A at: WatSan.eu
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  • F H Mughal
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Re: The Impact of Pit Latrines on Groundwater Quality

Thanks, Mr. Makowka. I appreciate.

Best regards,

F H Mughal

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  • Juergen
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Re: The Impact of Pit Latrines on Groundwater Quality

Hello Mr. Mughal,

usually, the distance between the point of pollution and the well should be equal to the distance corresponding to 50 days of groundwater flow. According to the aquifer, this may range from just a few meters to several hundred meters. Flow velocity of groundwater can be deduced from pumping tests or through tracer tests; however,

these norms were established based on results obtained from max. survival times of e. coli in groundwater in cool climates (N. America, Europe) and the survival of e. coli in regions as Sindh, where groundwater temperatures are generally above 25° C, are suspected to be different(longer), so greater distances would be needed. When water testing after the 2010 floods in Sindh, we found e. coli in almost all wells within the villages, at distances of > 100m, we frequently found NH4 (ammonium), which in field testing is usually attributed to bacterial activity in groundwater.

Due to the depths and poor design of almost all wells, we couldn't determine the source of pollution with certainty (animal faeces being found al around the wells) nor it's depth location within the aquifer (usually, pollution 'feathers' tend to extend laterally from the main direction of groundwater flow, but take much time / long distances to seep down into deeper sections of the aquifers).

Conventional 'good practices' in well construction might help to provide drinking water quality to the rural poor in Sindh in many areas.

Facts are stubborn things, but statistics are more pliable. (Samuel Langhorne Clemens)

Truth is what stands the test of experience. (A. Einstein)
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  • AquaVerde
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Re: The Impact of Pit Latrines on Groundwater Quality

Dear colleagues,

End 90's I used in South Africa a little computer based (on diskette) simple program from WRC, to determine possible contamination by VIPs before projects started. As fare I remember, one of the inputs been soil conditions. Unfortunately I lost the little program and the booklet by a flooding later on.

Maybe this little program it is still in use in South Africa as an improved version. Do anybody know this little WRC-program too?

Regards,
Detlef SCHWAGER

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  • F H Mughal
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Re: The Impact of Pit Latrines on Groundwater Quality

Dear Mr. Juergen,

Thank you for sharing useful information. I'm particularly delighted to read the information about Sindh, you gave. Thank you for that. If you have more information/reports on Sindh, please share those as well.

Regards,

F H Mughal

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  • kanalwolf
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Re: The Impact of Pit Latrines on Groundwater Quality

Dear colleagues,

I am sure that the well established "50-days-rule" is a useful concept to come up with some initial guidance for separation distances based on an assumed E-coli inactivation time of 50 days.

However, given the increased knowledge about viruses and also about the stochastic nature of this contamination problem, authorities in New Zealand have come up with a number of lookup tables for seperation distances for different aquifer settings and different thicknesses of the vadose zone, based on some quite convervative stochastic modelling.

You find the new Zealand Guidelines here:
www.envirolink.govt.nz/PageFiles/31/Guid...virus_transport_.pdf

"Guidelines for separation distances based on virus transport between on-site domestic wastewater systems and wells"
I have replied in a different thread in a similar manner, but i discovered that the link was not working.

The look-up tables are provided at the end of the document. Of course, they do not replace some hydrogeologic expertise.

As already mentioned by Jürgen, good practices in well design, well construction (appropriate sealing), well disinfection & pumping after contaminating flood events and and taking care of the immediate surrounding of the wellhead seam to be good first measures.

Actually, i would think that it could be a good idea if SuSanA would gather some key information on well siting and seperation distances adapted to low tech environemnts in a kind of factsheet document

Kind regards,
Leif


Dr Leif Wolf
Co-Lead of Susana Working Group 11 : Sanitation & Groundwater Protection

Program Manager at PTKA

www.researchgate.net/profile/Leif_Wolf/

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  • AquaVerde
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Re: The Impact of Pit Latrines on Groundwater Quality

Dear Leif,

Actually, i would think that it could be a good idea if SuSanA would gather some key information on well siting and seperation distances adapted to low tech environemnts in a kind of factsheet document


above I mentioned a little program from WRC "Made in South Africa" from the end 90', the results of it been: "separation distances adapted to low tech environments in a kind of fact-sheet document" based on various soil conditions.

Maybe some SUSANA-colleagues could "dig" the nice document/program out at WRC ( www.wrc.org.za/ ) by using own informal connection to the Commission, instead of SUSANA is "inventing the wheel again".

If I remember well the established "50-days-rule" is applied by this little WRC-program too.
In Germany this "50-days-rule" is still the first starting point for any well-plannings by DIN (German Industrial Standard)

Best egards,
Detlef

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  • kanalwolf
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Re: The Impact of Pit Latrines on Groundwater Quality

Good point, Detlef, I hope someone will find this document/source.

I will be most happy to have a look at this "wheel" and see if it is still rolling, once it surfaces again.

So many good thougths have been thougth already, but we need to polish them once in a while (and put this on websites like SuSanA), otherwise they get lost.

Kind regards,
Leif


Dr Leif Wolf
Co-Lead of Susana Working Group 11 : Sanitation & Groundwater Protection

Program Manager at PTKA

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  • Juergen
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Re: The Impact of Pit Latrines on Groundwater Quality

Dear Kanalwolf et al.,

thanks for the input; the 50-days rule is also applicable in the European Union, as far as I do know. Anyway, apart from good practices in well construction - these are really well and long-term established standards...-, the behaviour of virus might be very different from the behaviour of bacteria -as e. coli- in groundwater.

We should be careful on judging on transport of organic matter and bacteria around newly built wells and wells approaching their mid-term life expectance (i.e., from 10 to 25 years) since around older wells we might find well-established bodies of organic -living- matter of algae and bacteria forming organic fleeces around the well and possibly enabling e. coli and other not-so-harmless bacteria to reproduce, spread and survive longer in groundwater. Evidence for this is known, e.g., from the spread of f. cholerae in the Sundarbans in India and Bangladesh, where even seasonal influences as algae growth in rivers at the inset of the monsoon have their effect on bacteria inside wells fairly distant from these rivers.

Again, wells built following the established standards are the first and best protection against groundwater pollution through organic matter - and only samples taken from such wells allow hydrogeological guesstimates (or better) of transport distances and possible spatial extensions of plumes of pollution and transport velocities. All data taken from wells not corresponding to such standards, such as I mentioned from Sindh, just display faecal contamination or -generally- organic substances in the groundwater around these wells, without allowing judgement on the source of contamination itself.

Best regards,

Jürgen

Facts are stubborn things, but statistics are more pliable. (Samuel Langhorne Clemens)

Truth is what stands the test of experience. (A. Einstein)
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  • rajivkr
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Re: The Impact of Pit Latrines on Groundwater Quality

Dear AquaVerde,

Would you by any chance be able to indicate year of use, name of software, developer name, etc.? And was it from WRC?

Just to narrow down the search. It would help.

Rajiv
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  • AquaVerde
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Re: The Impact of Pit Latrines on Groundwater Quality

Dear Rajiv,

from CSIR or WRC end 90's
All "water"-NGO's in RSA used it.

It needs a search by a RSA water-NGO insider. I regret, outsiders would not get access any more.

Anyway, this old software will not end poverty-apartheid and some related environmental problems.

Regards,
Detlef

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