Panoply of technologies can be used for the provision of safe WSS, ranging from the simplest hand dug well to the most advanced biological wastewater treatment systems for the removal of nutrients. It is tempting to assume that the technologies, strategies, and standards employed in Europe and the USA represent a particular optimum to which all communities must aspire. Thus in certain situations there may be pressure to replicate these technologies in places or over timescales that are not necessarily realistic.
In fact the technologies, strategies, and standards in the West are the result of over 100 years of evolution, much of which occurred at an enormous cost that was only feasible at the time because of significant political and economic innovation. The technologies themselves have evolved largely heuristically, with many of the key strategies being developed more rapidly that the relevant basic sciences (especially chemistry and biology).
Thus the technologies cannot and do not represent an acme in development (which is still evolving). Moreover, it seems unlikely that if developed countries could start again they would reproduce the technologies and strategies that they currently employ and, therefore, it would seem illogical to assume that the slavish replication of these strategies will work in all communities at all times (Feachem et. al., 1983).
Broadly speaking WSS technological strategies can be divided into those relating to the collection, distribution, and treatment of faeces and other household wastes and those relating to the collection, treatment and distribution of water for drinking and other household tasks, though the importance of drainage and solid refuse collection must not be forgotten. European urban sanitation systems typically involve a flush toilet that feeds into a large, reticulated wastewater collection network that feeds into larger (and successively more expensive) sewers typically culminating in a wastewater treatment system. However sanitation need not be water-borne to be effective, and there are many highly-effective variations on the pit latrine. Though crude and poorly maintained pit latrines are unpleasant, even dangerous (they collapse!) very simple measures, such as simple cast squatting or sitting slabs, may make a latrine pleasanter to use and child friendly.
More sophisticated (and thus more expensive) refinements have been also widely employed such as the Zimbabwean Ventilated Improved Pit Latrine (VIP) or the Indian Pourflush system (which uses very low volumes of water). Other even more sophisticated designs have been proposed (typically in the West) and trialled, but not widely replicated. However, pit latrine emptying is generally a problematic area and, despite important technical advances, the treatment of pit-latrine wastes continues to be difficult. Novel approaches to sewerage have been developed in North-east Brazil (condominial sewerage) and have been refined and replicated in many other parts of the country and in South America.
There have also been analogous developments in Pakistan (the Orangi project). Moreover, an accompanying and often overlooked innovation in Brazil was the use of small cheap decentralised wastewater treatment systems that obviated the need for trunk sewers and thus helped reduce costs (decentralised sewage was subsequently reinvented in North America and Europe). In Europe there are several countries with a large population living in rural areas which is served by small systems not connected to large water supply or sewerage networks or even on-site, non-waterborne sanitation.
European urban water supply systems typically consist of a surface or groundwater supply and treatment system and a reticulated distribution system and very similar arrangements are employed, and are arguably appropriate, by many communities in developing countries. As it is well known, in LDCs the traditional reticulated pipe networks are often complemented or even supplanted by tankers, trucks, and small scale vendors, while local communities often meet their needs abstracting directly from either groundwater (wells and springs) or surface waters (lakes and rivers).
In addition rainwater or even fog may be collected but only on a relatively small scale. However, networked urban water supply in LDCs is often complicated by a range of problems including poor maintenance of the infrastructure, lack of materiél for water treatment, low water pressure, or illegal connections. Also, the provision of water is often affected by pollution of the water sources, whether naturally occurring or anthropogenic, and by the often neglected but crucial domestic post-collection storage practices.
The fact that these problems persist despite that simple effective water treatment systems that do not require extensive chemical inputs are available (such as horizontal roughing filters and sand filters) suggests that solutions cannot be reduced to technological fixes.
In this connection, although failure in WSS systems in LDC is common place, the causes of failure are rarely purely technical. It is widely acknowledged that failure can typically be attributed to some combination of poor social acceptability of the technologies being introduced, inadequate attention to financial or economic preconditions, and lack of good governance often resulting in top-down decisions and the alienation of the communities involved (UN-Habitat, 2003).
The need for an approach which integrates the technical, social, and economic dimensions of WSS and seeks to actively involve the community while taking into account local cultural preferences has been long recognised (Mara, 1996).
It is notable that successful and replicable sanitation strategies such as condominial sewerage in Brazil that are based on an integrated approach have failed when replication has taken place as a purely technical strategy with disregard for social and cultural preferences (Watson, 1995).