National Sanitation Task TeamDepartment: Water Affairs and Forestry, Health, Education, Provincial and Local Government,
Housing, Environmental Affairs and Tourism, Public Works, Treasury
Department: Water Affairs and ForestryYour partner in creating a better life for all
SanitationTechnology Options
SanitationTechnology Options
F O R A H E A L T H Y N A T I O NFebruary 2002
References:Franceys, Pickford & Reed (WEDC) “A guide to the development of on-site sanitation”, WHO 1992. • SMLC, Johannesburg, report to Executive Committee, “Review of sanitation ininformal settlements” 1999. • Guy Pegram, “A protocol to support peri-urban sanitation provision in the GJMC”, final draft, 2000. • Julia du Pisani, “Providing Sanitation in South Africa”,unpublished draft. • The Applicability of Shallow Sewer Systems in South Africa, Guy Pegram and Ian Palmer July 1999.
F O R A H E A L T H Y N A T I O N
IntroductionThe full range of technical options for providing adequate basic sanitation is still not widely understood. In particular, thereis little appreciation of the long-term financial implications of operating the various sanitation systems. As a result, communitiesand local governments are currently choosing technical options that, in the long term, are unaffordable and unsustainable.
Complications arise from the wide range of options available and the differing environments in which they must beimplemented. Experience shows that it is important to allow local solutions to be developed. The options include theventilated improved pit toilet in all its variations, composting toilets and on-site wet systems such as septic tanks, and fullwater borne systems.
Communities often face choices ranging from single pit ventilated improved latrines to double ventilated improved pit latrinesto urine diversion/composting latrines. These options promote household management of operation and maintenance. (Inmost cases, the cost of emptying a single pit every five years is estimated at between R35 and a still-affordable R60.)Where higher levels of service are chosen, the costs are a lot higher - as much as R500 per household per annum. Theinitial capital cost is also dependent on the choice of technology. One of the lessons learnt from the DWAF programme isthat it is possible to provide on-site dry systems for an initial, capital outlay of less than R1000. The Archloo, which isprovided to many cholera-affected areas, is an example of a facility that can be provided at a cost of R600 using localmaterials and local labour - and that can be put into large-scale production. However, such provision must be coupled withhealth and hygiene promotion if health improvements are to be ensured.
In this document you will read more about the various technical options that meet the requirements for basic sanitation.These need to be considered within all the sustainability requirements, e.g. affordability, operation and maintenance. Theoptions are divided into two categories: Dry on-plot systems (that do not require water for operation) and wet systems (thatdo require water for operation).The following information is provided for each technical option described:
• A technical drawing of the recommended option• A description of the options• An explanation of the principles of operation• Operational and institutional requirements• A summary of costs• Notes on previous user experiences and comments on these
Technical guidelines are available from the Department of Water Affairs and Forestry for on-site dry sanitation.
Please note: The capital cost of a given technology varies widely - depending on location, locally available materials,construction method, extent of existing infrastructure, etc.
Unimproved pit toilet• This system is not recommended (subject to bad smells and insect infestation)A top-structure around and /or over a pit, generally unlined where soil conditions allow, with a pedestal or squat-plate.
Chemical toilet• This system is not recommended (expensive and temporary)Various modern types. These utilise a water-diluted chemical in a receptacle below the toilet seat to render excreta harmlessand odourless. These are generally standalone units.
Bucket toilet• This system is not recommended (unhygienic sanitation system, environmentally undesirable)A top-structure with the seat positioned above a bucket or other container located in a small compartment beneath.
Communal toilets• This system is not recommended for household use (unhygienic)Toilet ”blocks”, which may be based on dry or wet systems as, outlined above.
Options not recommended
Dry on-plot systemsVentilated Improved Pit (VIP) toilet
A top-structure over a pit. The pit is vented by a pipe over which a fly-screen is fixed. The pit may be lined (recommendedwhere emptying is required), or unlined where soil conditions allow.
Vent pipe
Seat cover
Pedestal
(May be extendedto base of pit in poorground conditions).
Air (ventilation)
Pit collar
Cover slab
Fly screen
Hand dugor mechanicallydug pit
Principlesof operation
Operational andinstitutional
requirements
Costs Experience andcomment
Waste drops into the pit whereorganic material decomposesand liquids percolate into thesurrounding soil. Continuousairflow through the top-structureand above the vent piperemoves smells and vents gasesto the atmosphere. A darkenedinterior is maintained causinginsects entering the pit to beattracted towards the light at thetop of the vent pipe and trappedby the fly screen. A separatehand washing facility is required.
Locate to prevent ingress ofstorm water to pit, as well as inc o n s i d e r a t i o n o f l o c a lgroundwater use and conditions.Does not accept domesticwastewater. Cannot be placedinside house. Ensure access formechanical pit-emptying andavailability of sludge treatmentand disposal where required.Ensure repair/replacement ofdamaged/worn materials.
Capital: may range from R600-R3000, depending onhouseholder input and choice ofmaterials.
Operating: R60 per year ifemptied once in 5 years.
Widely used internationally andin rural and peri-urban areas ofSouth Africa. Most successful inwater-scarce environments.Failures generally due toinadequate user educationand/or poor design andconstruction. Costly adaptationscan result where shallow rockor shallow water tables occur.
Vent pipe
Air (ventilation)
Fly screen
Drop hole andvent pipe holesealed whenpit not in use
Swap pedestaland vent pipefrom other sideif pit to be used
Seat cover
Pedestal Moveable coverslab (so that pitcan be emptied)
Lined and sealedcentral wall
Full pit
Principlesof operation
Operational andinstitutional
requirements
Costs Experience andcomment
As for the VIP toilet.One pit is used until filled towithin about half a metre of thetop. The defecation and ventpipe holes are then completelysealed and the other pit used.The contents of the first pit aredug out after a period of at leasttwo years, once the contentshave become less harmful.
As for the VIP toilet, except thatpromotion of manual emptyingby the householder is usual, anduse of decomposed waste as asoil condit ioner possible.Suitable disposal site necessary.
Capi tal : R2 500-R4 500depending on householder input.
Operating: R35-R135 every 2years depending on localgovernment involvement,householder willingness tohandle waste, disposal options.
Resistance to handling ofdecomposed waste and timelychangeove r o f p i t s byhouseholders has often beenovercome through education andover time - both internationallyand in SA. This VIP alternativeis often applicable where rockyor groundwater conditionsprohibit deep excavation.
Ventilated Improved Double Pit (VIDP) toilet
A single top-structure over 2 shallow pits, side by side. Only one pit - vented by a pipe protected with a fly screen - is inuse at any time. Generally lined and the central wall fully sealed to ensure isolation of one pit from the other.
Vent pipe
Pedestal
Air (ventilation)
Access cover
Seat cover
Turning and removalof composted material
by hand
Urine outlet pipeto soakaway orcollection pot
Fly screen
Urine diversion
Principlesof operation
Operational andinstitutional
requirements
Costs Experience andcomment
Waste is deposited in thechamber and dry absorbentorganic material, such as woodash, straw or vegetable matteris added after each use todeodorise decomposing faecesand/or control moisture andfacilitate biological breakdown(composting). Urine may beseparated/diverted through useof specially adapted pedestals.This may be collected and usedas a fertiliser. In desiccationsystems, ventilation encouragesthe evaporation of moisture.
Does not accept domesticwastewater. Ensure ease ofaccess by householder andpromotion of manual ‘turning’ ofcompost and removal ofcomposted/desiccated material.Suitable disposal site/areanecessary.
Capital (variable depending onsystem and householder input):R3 000-R4 000 for commercialsystems.
Operating: R35-R500 perannum, depending on localgovernment involvement andhouseholder willingness tohandle waste, and disposaloptions.
Control of moisture content isvital for proper operation.Contents often become too wet,making the vault difficult andunhygienic to empty, as well asmalodorous. UD systems in SAstill being monitored but appearto be accepted by certaincommunities and workingwithout significant problems.Burning of compost prior toremoval also being tested in SA.Proprietary systems have beenpiloted in SA, generally withinconclusive results as to theirlikely success on a large scaleand under varying conditions.User educational requirementsand continuous input significantfor proper operation in terms ofthe composting process.
Composting/urine diversion (UD) toilet
A single top-structure over a sealed container, which could be one of two chambers side by side (as for the VIDP), withaccess for the removal of decomposed waste. A vent pipe may be installed to encourage drying of the waste.
Low flush pedestal
Access cover
Seat cover
Lined pit
Water trap
Water tank to be filledby hand or use aseparate container
Wet systemsPour-flush toilet
A toilet with a water-seal arrangement: a pan trap fitted into the floor slab, and optionally discharging through a short stretchof pipe or channel.
Principlesof operation
Operational andinstitutional
requirements
Costs Experience andcomment
After defecation, the panrequires flushing with a few litresof water. The water retained inthe pan provides a seal againstsmell, flies and mosquitoes.
Appropriate for small volumesof water and can acceptdomestic wastewater - generallycarried by hand to the latrine.Ensure access for mechanicalemptying of contained waste,and suitable subsoil drainage(high reliance on the soilenvironment in rendering theeffluent harmless) and/oravailability of sludge treatmentand disposal.
Capital: R2 000-R3 500 whichcan increase where soils are notwell suited to drainage.
Operating: R150-R300 perannum where subsoil drainageis available.
In te rnat iona l acceptancedemonstrated where water isused for anal cleansing and userssquat. Blockages occur throughuse of inappropriate analcleansing material. Offset pour-flush can allow location of toiletinside house, but generally largerflushing volumes are required.Experience in SA has seenfailures through lack of usereducation and/or poor design andconst ruc t ion , use whereinappropr iate and l imitedprovision of affordable emptyingservice.
Water tight tank
Low flush pedestal
Water tank maybe hand filled
Seat cover
Soakaway(soakpit or drainage trench)
Sludge
Liquid
Scum
Access cover
Air (ventilation)
Fly screen
Vent pipe
Down pipe maintainedbelow water level
Digester
Principlesof operation
Operational andinstitutional
requirements
Costs Experience andcomment
After defecation, the panrequires flushing with a few litresof water. An aqua-privy requiresthe addition of water to keep theend of the chute submerged.Containment of the waste mayvary from a sealed container toa solids collection system andeffluent soakaway.
Appropriate for small volumesof water and can acceptdomestic wastewater - generallycarried by hand to the latrine.Ensure access for mechanicalemptying of contained waste,and suitable subsoil drainage(high reliance on the soilenvironment in rendering theeffluent harmless) and/oravailability of sludge treatmentand disposal.
Capital: R2 000-R3 500 whichcan increase where soils not wellsuited to drainage.
Operating: R150-R300 perannum where subsoil drainageis available.
Internat ional acceptancedemonstrated where water usedfor anal cleansing and userssquat. Blockages occur throughuse of inappropriate analcleansing material. Experiencein SA has seen failures throughlack of user education and/orpoor design and construction,use where inappropriate andlimited provision of affordableemptying service.
Aqua-privy and soakaway
A toilet with a water-seal arrangement: a straight or curved chute running from the seat to below the water level with someform of waste collection and disposal system.
Full / low flush toilet
Water trap
Vent pipe
Access cover
WatertighttankLiquid
Sludge
Air (ventilation)
Fly screen
Conservancy tank
A storage system, i.e. a sealed tank, where low-flow or full-flush toilet systems are used.
Principlesof operation
Operational andinstitutional
requirements
Costs Experience andcomment
Waste is flushed into the tankwhere it is contained in isolationf r o m t h e s u r r o u n d i n genvironment before removal bytanker for treatment.
Tank sizing dependent on flushvolumes, domestic wastewaterlevels and f requency ofemptying. Ensure access formechanical emptying andavailability of treatment anddisposal facilities.
Costs depend on size andemptying frequency.
Cost: At R2 000 - R5 000depending on top structure andtank volume.
Operating: R550 per householdper annum (based on anestimated emptying cost of R181per tank) assuming the tank isemptied, on average, 3 timesper year.
Widely used, particularly in moresens i t ive so i l and geo-hydrological environments.
No Water Consumption System (NOWAC)
Principles of operation Operation and Institution Costs Experience and Comment Fill main chamber with water to activate the system. No additional water will be required in future. Waste drops into the water in the main chamber where the organic material decomposes. This process is natural and executed by organisms. The waste moves around in the main chamber for a period of approximately 100 days. The brown water moves into the second chamber. This chamber is fitted with an anaerobic filter and is situated in the main chamber. It destroys approximately 98% of al dangerous pathogens before it flows over into an anaerobic filter where the remains of the pathogens are destroyed by organisms and oxygen. The volume of the overflow equals the volume of the waste per person. This overflow of uncontaminated water flows into a soak away, which can be seen as an additional filter.
Operates: • Without additional water • With only the seat as
mechanical part • Without any chemicals No maintenance required for 15 – 20 years. After 15 – 20 years the sand layer at the bottom of main chamber is removed with a pump after which the system will work for another 15 – 20 years. Note: Only sand and not the water will be pumped out.
Capital: 5000 – 6000 per unit which includes: • The complete system • The concrete top
structure • The transport • The installation • The training of each
household Note: Installation costs can increase in rocky areas and against steep slopes. Operating: No costs up to 15 – 20 years.
Similar systems are accepted internationally in echo sensitive areas and where water is scarce.
Added: April 2006
Full bore waterborne sewerage
An in-house full-flush toilet connected to a sewer (pipe) network which drains to a wastewater treatment facility.
Principlesof operation
Operational andinstitutional
requirements
Costs Experience andcomment
Waste from the toilet, andpossibly domestic wastewater,is flushed using significantvolumes of water into the sewersystem for removal to atreatment facility. There areseveral types of such facilitiesand these treat effluent to highstandards prior to discharge intothe aquatic environment.
Requires a re l iable anduninterrupted household waterconnection and spatially regularpermanent settlements. Specificdesign criteria must be appliedthroughout the seweragenetwork. Skilled, organised andef fec t i ve opera t ion andmaintenance capabil ity isrequired for sewers and the fullfunctioning of wastewatertreatment facilities.
Capital: R6 000-R7 000 takingbulk and sewerage costs intoaccount.
Operating: R400-R800 perannum.
Widely used and generally theaspiration of all South Africansalthough unaffordable to many,particularly in terms of accessto suf f ic ient volumes ofhousehold water. Appropriateanal cleansing material isrequired. The health conse-quences o f fa i l u re a redevastating in comparison to on-site, dry sanitation.
Full flushtoiletWater trap
Boundaryfence
Roadway
Sewer in road reserve
Rodding eye
Household wastewater
Inlet works
Primarytreatment
Secondarytreatment
Tertiarytreatment
To river
Wastewater treatment works
Full flush toilet
Water trap
Septic tank
Access cover
Sludge
Liquid
Scum
Small bore sewer tomain sewer in road
To optionA or B
B
Soakaway(soakpit or drainage trench)
A
Inlet works
Primarytreatment
Secondarytreatment
Tertiarytreatment
To river
Wastewater treatment works
Septic tank and soakaway or small bore solid-free sewer
Septic tank and soakaway: An in-house full flush-toilet connected via pipe and plumbing fixtures to an undergroundwatertight settling chamber (the ‘digester’) with a liquids outlet to a subsoil drainage/soakaway system.
Small bore solid-free sewer: An in-house toilet discharging to a septic tank (or on-site digester) with liquids disposal viaa small diameter sewer to a central collection sump or existing sewer system.
Principlesof operation
Operational andinstitutional
requirements
Costs Experience andcomment
Septic tank and soakawayWaste from the toilet, andgenerally domestic wastewater,is flushed into the settlingchamber where it is retained forat least 24hrs to allow settlementand biological digestion. Partiallytreated liquids then pass out ofthe tank and into the subsoildrainage/soakaway system.Digested sludge gradually buildsup in the tank and requireseventual removal by tanker.
Requires a reliable householdwater connection. Specificdesign criteria must be appliedto the settlement tank andsoakaway system. This optionis applicable only in areas of lowsettlement density and wheresoils have a high ability to draineffluent away. Ensure accessfor emptying of tanks by vacuumtanker, as well as availability ofsludge treatment and disposal.
Capital: R7 000-R8 500.
Operating: R200-R450 perempty ing, depending onemptying frequency.
Widely used by formal ruralhouseholds and farming areas,where reliable water supply isavailable. Provides a high levelof service and user convenience.Failures due to poor design andconstruction, and use ofinappropriate anal cleansingmaterial. Soakaway system isparticularly prone to failure inthe long-term if detailed soiltesting is not carried out.
Small bore solid-free sewerAs for the septic tank andsoakaway except that the liquideffluent is conveyed by a systemof small-diameter pipes to acommunal treatment point(which may be off-site treatmentworks reached either via existingsewerage or by tanker).
Although its water requirementsmay be less than those of aseptic tank and soakaway, ahousehold connection is needed.Ensure access for emptying ofseptic tank, as well as availabilityof sludge treatment and disposal.Routine maintenance of pipenetwork essential.
Within the septic tank andsoakaway range detailed aboveif septic tank systems already inplace, otherwise capital costmuch higher.
Not widely used in South Africa,except where existing septic tankand soakaway systems havebeen converted for convenienceand/or environmental reasons.Failures as for septic tanksabove, and due to lack ofmaintenance of the pipenetwork.
Low flushtoiletWater trap
Inspection box Junction box
Sewer fromnext house
Inlet works
Primarytreatment
Secondarytreatment
Tertiarytreatment
To river
Wastewater treatment works
Shallow sewerage
A toilet, usually in-house, flushed using lower volumes of water than either conventional sewerage or septic tanks, to smallerdiameter sewers laid at flatter gradients and shallower depths between dwellings on a block. On-site shallow inspection
chambers are provided.
Principlesof operation
Operational andinstitutional
requirements
Costs Experience andcomment
Waste from the toilet andpossibly domestic wastewater,but at much lower volumes thanfor conventional sewerage, isflushed into the on-site seweragesystem and progressivelywashed down to either adedicated treatment facility orinto street sewers and then onto a major treatment works.
Requires reliable householdavailability of water and high levelsof connection into the seweragesystem are necessary. Can,however, be laid out in less formaland spatially irregular settlements.Less stringent design criteria - butorganised and effective operationand maintenance capability isrequired. This can be delegatedto residents for on-site sewers.Significant user education anda c c e p t a n c e o f s h a r e dmanagement of the system iscritical.
Capital: R 2500 to R 3000 -savings of up to 50% overconventional sewerage capitalcosts.
Operational: R300 - R450assuming that all maintenanceis provided by the serviceprovider. Drops to R312 whereresidents are responsible foroperation and maintenance ofblock (not bulk) sewers.
Have not been used widely inSouth Africa although used, withreported success, under a widerange of conditions in a numberof South American countries,Ghana, Pakistan and Greece.Pilot projects have beencompleted in Durban and FreeState, with ongoing monitoringto determine overall success andsustanability. These indicatesavings of up to 50% overconventional sewerage capitalcosts.
Who can be contacted?
Department of Water Affairs and ForestryMs T Mpotulo(012) 336 [email protected] Bag X313Pretoria, 0001
Department of HealthZama Zincume(012) 312 0503/(012) 323 [email protected] Bag X828Pretoria, 0001
Department of EducationCharles Sheppard(012) 321 5470/(012) 321 [email protected] Bag X895Pretoria, 0001
Department of HousingJohan Wallis(012) 421 1440/(012) 341 [email protected] Bag X655Pretoria,0001
Department of Provincial andLocal GovernmentZama Nofomela(012) 334 0750/(012) 334 [email protected] Bag X804Pretoria ,0001
Department of EnvironmentalAffairs and TourismLucas Mahlangu(012) 310 3536/(012) 320 [email protected] Bag X447Pretoria, 0001
Department of TreasurySimon Maphaha(012) 326 6311/(012) 315 [email protected] Bag X115Pretoria, 0001
Department of Public WorksLorraine Malebo(012) 337 [email protected] Bag X65Pretoria, 0001
SALGAMr Thabo Mokoene (CEO)(012) 338 6700/[email protected] Box 2094Pretoria, 0001
National Sanitation Task Team DWAF Regional Offices
WESTERN CAPELionel Visagie(021) 950 [email protected] Bag X16Sanlamhof7532
MPUMALANGARichard Mbambo(013) 752 [email protected] Bag X11259Nelspruit, 1200
KWAZULU-NATALViv Naidoo(031) 336 [email protected] O Box 1018Durban, 4000
FREE STATEGabriël Hough(015) 430 [email protected] O Box 528Bloemfontein, 9300
NORTHERN CAPEAntonino Ross(053) 831 4125/(053) 831 [email protected] O Box 416Kimberley, 8300
EASTERN CAPEMfusi Mpendu(043) 643 [email protected] Bag X7485King Williams Town, 5600
GAUTENGJohan Enslin(012) 392 [email protected] Bag X8007Hennopsmeer, 0046
NORTH WESTLogogang Bogopa(018) 384 3270/(018) 392 [email protected] Bag X5, Mmabatho, 2735
NORTHERN PROVINCEMasia Mgwambani(015) 290 1238/(015) 295 [email protected] Bag X9506Pietersburg, 0700
