Making VIP latrines succeedby Richard N. MiddletonIn a recent Waterlines article (Vol.13, No.2),Robert Reed discussed the conditions underwhich pit latrines may not be suitable sanitationsystems. Although a valuable reminder that eventhe simplest technologies may not always work,Richard Middleton believes the uncomfortabletruth is that often there is no feasible alternative.He focuses on the double-pit VIP latrine, 'the onlytype of dry-pit latrine that can provide apermanent, safe, sanitation solution.'!

areas.4 The VIP represents an improve-ment for the family, if designed care-fully: the slab covering the twin pitsprovides a solid, flat, clean area suit-able for storage and laundry, and maybe very welcome (especially duringrainy seasons, when the rest of thecompound may be muddy). Whereplot sizes are really small, it may befeasible to locate the pit-access hatchesoutside the property itself (for exam-ple, under the edge of an alleyway, ifthere is no traffic).

Figure 1. The ventilated improved double-pit (VIP) latrine.

PEOPLE SHOULD NOT be forced toaccept and pay for solutions that theydo not want. Expectations can beunrealistic, however, so telling peoplewhat is available, and helping them tomake better-informed decisions,should always be part of projectplanning and design. The results maybe unexpected: for example, manypeople in Kumasi, Ghana opted forVIP latrines rather than sewered sys-tems, because they were worried aboutcosts, water-supply reliability, and thepossible abuse of shared flush toilets.2

Discussions with the communitymay tell the planners that designsshould be revised. For example, therewere some well-known VIP failuresin Botswana in the early 1980s; peoplewere bathing in the VIP latrinesbecause they offered privacy, and theslab foundations, which were notdesigned to have water seeping pastthem, subsided. As a result, the VIPdesign was changed to providestronger foundations;3 another solutionis to build separate shower and bathingareas, perhaps linked to each other andto the main house by 'breezeways'.People must be encouraged to tellplanners how they want their housesto be arranged; in most cases, thesimplest way to do this is to builddemonstration models in the commu-nity, and to let everyone inspect themand make comments.

Planners should also respect tradi-tional 'latrine culture' (such as prohibi-tions on latrine sharing). Some expertsbelieve, however, that when ruraldwellers move to the city, they experi-ence such major life-changes, thatsanitary preferences also adjust.

Another concern is that children willnot use the latrines, because they fearfalling into the pit. This may be anexaggerated worry (children may bejust more likely to defecate where they-are), but it should be investigated, aschildren's faeces tend to be highly

pathogenic. The solution may be modi-fication of the pedestal or squat slab,by adding an insert or a separatechildren's seat.

A more serious problem is fear ofthe dark interior, and of possiblelurking insects. A dark interior wasoriginally specified to ensure that flieswithin the pit were attracted to thebright ventpipe and trapped, but itseems that some light can be admittedwithout affecting the fly-catching, pro-vided that the ventpipe is large enough,and the screen is kept clean. Even insquatter communities, a high propor-tion of residents often has some formof electrical connection, and so alow-wattage bulb outside the VIP canalso provide reassurance at night.

Space constraintsLack of space is not usually a majorproblem, except in very high-density

RemovableCoverslabs

/t \

Latrine emptyingWhile VIPs have few operation andmaintenance (O&M) requirements,they should be emptied periodically(typically, every three to five years).Municipalities often have problems inproviding a reliable, effective, andaffordable mechanized service,S soplanners should ensure that emptyingcan be done by the family, or by privateentrepreneurs. This involves establish-ing not only that people are willing tohandle stabilized humus, but also thatthere is some safe place for ultimatedisposal (ideally, of course, on thefamily's vegetable patch or fruit trees).

Groundwater and surface-water protectionAll on-site sanitation systems, VIPsincluded, will discharge some effluentinto the soil. With a VIP, the amountwill be small, because it is a dry

lSuperstructure

WATERLINES VOL.l3 NO.4 APRIL 1995 27

system, and because much of the watercontained in excreta will be exhaustedup the ventpipe. Unless the soil is veryopen, or the water-table is shallow,most harmful constituents will notreach underlying aquifers. The mostserious concern is usually over possi-ble nitrate contamination of ground-water, in particular, where there aremany VIPs in a small area.

In special cases, such as underkarstic conditions, or where it isessential to maintain aquifer quality,the VIPs may be modified. Forexample, sealed vaults may be usedinstead of pervious pits, or in highwater-table areas the 'pits' may bepartially above ground. Before pro-ceeding to expensive modifications,or changing technologies, however,planners should take account of threeimportant factors:o Eventually, all shallow aquifers

under urban areas will probably bepolluted, not only from latrines, butalso from many other contaminants(from small industries, vehicle serv-icing etc.). Even deep aquifers maybecome polluted if uncontrolledconstruction, such as sinking pilesor other foundations, penetratesoverlying impermeable strata. Ob-taining water from more distant andbetter-protected sources is probablythe only long-term safe solution.As a general rule, adjusting thewater supply is easier and cheaperthan trying to change people'ssanitation habits, or controlling dis-charges.

o VIPs are not the only forms ofsanitation that discharge into thesoil. Traditional pit latrines havesimilar characteristics (except thatthey are often deeper and are neveremptied, so buried pollutants con-tinue to increase), septic tanks aredesigned to leach into the soil, andsewers leak (especially in develop-ing countries, where constructiontechniques are often poor and trafficdamage high).

o In most urban areas, storm water isheavily polluted. Watercourses intowhich storm drains discharge, andany aquifers recharged by storm-water, are likely, therefore, to be-come polluted, regardless of localsanitation systems.

Sullage management andsurface-water protectionSullage management has always beengiven very low priority in sanitationprogrammes. It was not discussed inany detail in the original 1976-8 WorldBank research project on low-cost

sanitation alternatives,6 and is barelycovered in the latest WHO handbook.?Perhaps, in comparison with the ex-tremely serious environmental andhealth consequences of, almost univer-sal, inadequate excreta disposal, sul-lage management has been judged tobe less critical. There is also theawkward fact that, in most cities,dealing with sullage means keepingstorm drains flowing freely; that meansadding both storm drainage and solidwaste management to the list of majorproblems that must be solved simulta-neously.

Sullage can be disposed of on-sitein many cases, using soakaway or,ideally, for crop production by eva-potranspiration systems. Maintenance(for example, of grease traps) may bea problem, however, and is verydependent on user education and moti-vation. Again, demonstration projectsand readily available local support areneeded.

Before condemning VIPs for failingto manage sullage properly, however,critics should recall that septic-tanksystems also often discharge highlypathogenic material directly to stormdrains, and that most sewage-treatmentplants in developing countries dis-charge effluents - not much betterthan raw sewage - into watercourses,

Ventilation efficiency drive in Jamaica- building the ventpipe from 8-inchhollow concrete blocks.

drainage channels, or close inshore.Even totally untreated sullage presentsless of a health and environmenthazard than these discharges. Upgrad-ing on-site sullage management as faras possible may be preferable, onenvironmental and public-healthgrounds, to switching to another'higher' technology.

Most existing publications on sul-lage management originate from indus-trialized countries, and are not readilyconverted to operational guidelinesrelevant to developing countries. Thisomission needs to be remedied as soonas possible.

Odour and fly control -ensuring good ventilationFailure to clean the fly screen over thetop of the ventpipe is a very likelycause of VIP 'failure'; it results in·reduced air flow (and a greater risk ofsmells inside the VIP), and, by reduc-ing the amount of light travelling downthe ventpipe, impairs its fly-trappingproperties. This is not strictly a failureof the technology, but of the accompa-nying education programme; usersneed to know that if they do not cleanthe screen, there will be unpleasantconsequences! The choice is thentheirs.

A more serious problem, which mayindeed lead to failure (or at least to theVIP becoming unacceptable in thecommunity) is progressive loss ofventilation as population density in-creases, houses are crowded together,and second storeys are added to somebuildings. Ventilation efficiency fallsas more obstructions get in the way ofwind flow. A solution being tried inJamaica is to build the ventpipe from8-inch hollow concrete blocks: thehollows form twin chimneys for eachpit and, if the vent does not workefficiently, it can be raised severalcourses.

With mixed-height housing, or onsteep slopes, however, there is the riskof ground-level VIPs dischargingodours at the window-level of adjacenthomes; a well-ventilated VIP maydelight the owner, but torment theneighbours! There is no obvious solu-tion, but one that seems feasible wouldbe to have a sealed 'light well' on eachpit (to trap flies), and a communal tallstack for venting purposes.

Persisting with VIPs -comparative costsIn most cases, VIP latrines will besubstantially cheaper than sewerage orseptic-tank systems, if all costs aretaken into account.6 Compare thephysical inputs: to construct a VIP andwashing area, the amount of materialsneeded is similar to building a bath-room, septic tank, and drain field, orfor a bathroom and a connection to astreet sewer, but the VIP does not haveoff-site construction costs (trunk sew-ers and sewage-treatment facilities;

28 WATERLINES VOL. 13 NO.4 APRIL lY95

Slip-sliding away: the collapse of pit latrines - such as these in Botswana - led to the introduction of the douhle-vault VIP.

septage hauling and treatment). O&Mcosts are negligible, while any water-borne system needs, primarily, waterto make it function, and also involveshigh O&M costs for conveyance,treatment, and final disposal.

The cost of flushing water - afactor often forgotten in costing sanita-tion options - is significant (andmany poorer households will not havethe house water connection necessaryto make flushing systems feasible).What is more, when many urban areascannot provide even minimal, reliable,continuous water services, and whenthe cost of new water sources is likelyto double or triple over time,8 it isobviously undesirable to adopt water-intensive systems unless there is sim-ply no other option available.

ConclusionVIP latrines are, in general, a safe andreliable technology. Of course, unlessplanned carefully, they can fail. Eventhen, the solution in most cases is notto abandon the VIP, but to examine thecauses of the failure and deal withthem. Unless the original selection wascompletely misguided, or circum-stances have changed radically, thiswill almost invariably prove morecost-effective than changing to anothertechnology.

Planners must be far more attentiveto the community's ambitions andpreferences. Seeking out views from awide range of potential users, buildingdemonstration models for actualhouseholds - and monitoring reac-tions - and changing designs ratherthan trying to change people, will helpto ensure success .•

Notes and references1. Simpler types of pit latrine (such as the

Mozambique unvented design: Brandberg,Bjorn, 'Improved sanitation using theSanplat System', Waterlines, Vol.l2, No.4)are simple and low-cost, but cannot beincorporated into the house structure, and arenot permanent; they are not comparable,therefore, with the VIP.

2. Whittington, Dale, Lauria, Donald T., andWright, Albert M., 'Household demand forsanitation services: a case study of Kumasi,Ghana', INUWS Water and Sanitation Re-port No.3, World Bank, Washington DC,1992.

3. Van Nostrand, John, and Wilson, James G.,'The ventilated improved double-pit latrine:a construction manual for Botswana', TAGTechnical Note No.3, World Bahk, Washing-ton DC, ]983.

4. Multi-storey housing is not usually suited toVIPs, despite traditional solutions, such asthe 'Yemeni long drop'.

5. Emptying remains a problem even on long-established and successful programmes (see,for example, Blackett, Isabel C., 'Low-costurban sanitation in Lesotho', Water andSanitation Discussion Paper No.IO, WorldBank, Washington DC, 1994). Unfortu-

nately, applied research of this sort is not nowreceiving much international attention.

6. Median values for the Total Annual Cost perHousehold (TACH) published in a WorldBank global research project were: pitlatrines: 26.0; conventional septic tanks:370.0; conventional sewerage: 362.1 (1978US$l, Kalbermatten, John M., DeAnne S.,Julius, and Gunnerson, Charles G., Appropri-ate Sanitation Alternatil'es: A te('hniml alldeco/lomic appraisal, The John HopkinsUniversity Press, 1982. This analysis, likemost others, omitted the cost of the 'soft-ware' needed to ensure project success, andalso the cost of sullage disposal for on-sitesolutions. It is inconceivable, however, thatthese omissions would offset the cost advan-tage of the on-site solutions (14: I in the caseof pit latrines).

7. Franceys, R., Pickford, J., and Reed, R., AGuide to the Del'elopme/lt of On-Site Sanita-tiOIl, WHO, Geneva, 1992.

8. World Bank data shows that, in many cities,the cost per cubic metre of next source ofwater will be two or three times higher thanthat now in use (Bhatia, Ramesh, andFalkenmark, Malin, 'Water resource policiesand the urban poor', Water and SanitationCurrents, World Bank, Washington DC,1993).

From 1978 to 1985, Richard Middletoll wasProject Mallager of the Technology Adl'isoryGroup (TAG) in the World Bank. specializing illthe del'elopment of low-cost sanitation indel'eloping countries. He is currently VicePresidelll of Kalhermatten Associates, Inc .. acOllsulting firm specializing ill water and wastesmanagement ill del'eloping coullIries. He can he

faxed at: +1 3015980148.

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