Wednesday, 16 January 2008

Rural sanitation: eThekwini latrines

I’m personally more interested in periurban sanitation, but of course rural sanitation is very important as well. Some of the options are pretty well known − VIP latrines and pour-flush toilets, for example. Then there are the various ecological sanitation variants such as the Arborloo and the Fossa Alterna (I may not think much of EcoSan in periurban areas but it’s certainly more than OK in rural areas if that what the users want − if you’re really interested in rural EcoSan, then read the excellent Toilets that make compost: Low-cost, sanitary toilets that produce valuable compost for crops in an African context by Dr Peter Morgan). But there’s another option for rural sanitation that is less well known and this is the “urine-diverting alternating twin-vault ventilated improved vault latrine” − which is more than a mouthful, so I abbreviate it to “UD VIV latrine” or even “eThekwini latrine” after the place in South Africa where it was developed. An excellent description is given in eThekwini's Water & Sanitation Programme (this also includes the highly innovative “ground tank” water supply system developed by eThekwini Water) published by WIN-SA. These latrines are wholly above ground (so they have vaults not pits) but otherwise they operate in rather the same way as alternating twin-pit VIP latrines, except that urine is diverted away from the vault to an adjacent soakaway − so the squat-pan or pedestal seat unit is a standard EcoSan urine-diverting one (but this is the only similarity between eThekwini latrines and EcoSan systems); in these latrines in eThekwini there’s also a urinal which discharges to the soakaway − but this is an optional feature. The point of urine diversion in these latrines is to prevent the vault contents becoming too wet, so that they can dehydrate properly (often some ash or soil is added to the vault in use to aid this process). Then, once a year the owner empties the vault not in use using a long-handled shovel and buries what s/he takes out (it’s much easier to do this than empty the pit of a VIP latrine), and then the vault just emptied is put into use (and the other one starts its 12 months of dehydration and pathogen die-off). And, of course, what comes out of the vault isn’t remotely like what went in! [Actually it’s quite easy to convert these eThekwini latrines to ‘proper’ EcoSan systems if that’s what the users want: the diverted urine is used as a fertilizer, not ‘wasted’ in a soakaway; the dehydrated vault contents are used as a compost/soil conditioner; and any greywater used for irrigation.]