Introduction
Water recycling is the process by which individuals harness, treat and reuse water for various purposes. It may occur through water reclamation. This involves the treatment of sewage effluent for domestic and commercial use. Alternatively, recycled water may come from storm water or rain water.
Potable use is the human consumption of recycled water while planned reuse refers to deliberate treatment of wastewater for other uses. Recycled water holds a lot of promise in the field of agriculture and industry, but its application as a potable source is still quite contentious, limited and risky.
Whether recycled water is safe for drinking
The question of whether recycled water is safe for drinking is of high relevance to a discussion on water-borne diseases because raw waste water contains high amounts of faecal matter, so it takes a rigorous and fool proof method to eradicate all disease-causing pathogens in recycled waste water.
Ashbolt (2004) explains that ingestion of unsafe drinking water transmits waterborne diseases. Usually, the water supply system of predisposed communities is susceptible to faecal contamination; over 1415 species of pathogens can be found in untreated waste water. Urine and faeces transmit these illnesses and may lead to severe complications or death. Typical examples include cholera, typhoid, gastroenteritis, infectious hepatitis, bacillary dysentery and amoeba, rotavirus, Escherichia Coli and Guardia Lamblia.
Treatment of waste water may minimise certain pathogens, but in highly infected water, it is difficult to eliminate all of them. Furthermore, recycling methods need to correspond to the development of new water-borne diseases. Scientists must also be aware of the genetic evolution of pathogens, which may make conventional treatment methods inadequate. Chemicals may also threaten public health if present in recycled water.
Conventional treatment may eliminate some chemicals, but could leave trace elements. Esposito et. al. (2005) affirm that the health effects of trace contaminants are still unclear at this point. Some organic compounds can disrupt hormonal systems even under extremely low concentrations. The international public health community is yet to create standards that would regulate treatment of waste water.
Therefore, parties must use a multi-thronged approach which would require elimination of all the threats at different levels (Steyn et. al. 2004). This is not just painstaking; it may cause excessive use of municipal and government resources. Toze (2006) explains that membrane filtration is one of the few effective routes of treating wastewater for portable use. However, it is quite expensive and takes a long time to complete. Jimenez and Chavez (2004) underscore the need for rigor in the treatment of wastewater for domestic purposes.
They assert that one must follow the fate of all the pollutants in the effluent in order to ascertain that they are absent. Esposito et. al. (2005) also outline some of the processes that waste water must go through during treatment. Disinfection and filtration systems in combination with secondary water treatment are effective for removing a portion of pathogens. The resulting product would only be sufficient for irrigation or non potable use.
On the other hand, ultrafiltration would minimise the risks associated with suspended particles. Sometimes certain pathogens are resistant to these processes. For instance, if one uses tertiary treatment on recycled water, one is likely to find viruses like cryptosporidium (Toze 2006). Elimination of chemicals is also essential in making recycled water safe for ingestion.
It would include the use of a series of treatments like nano-filtration, advanced oxidation as well as reverse osmosis. Ion exchange, biological degradation and chemical precipitation, are some synonyms of the above processes (Morud 2009). Owing to the complexity and diversity of disease-causing organisms and compounds in raw waste water, it is difficult to assure consumers of complete eradication of these pathogens in drinking water.
A number of advocates claim that recycled water is safe for drinking because water supply for key cities still comes from downstream rivers, which contain sewage effluent. However, using such a justification would be replacing one ill with another. It is one thing for cities to source their water from downstream rivers, with possible sewage contaminants.
On the other hand, when the concerned institution deliberately takes sewage effluent, then this increases the concentration of pathogens (DTI 14). It would increase the health risks of the population substantially when countries replace contaminated river water with sewage effluent.
Toze (2006) states that the concentration of pathogens in raw water supply highly affects the risks associated with treated waste water. If these sources have a high concentration of pathogens, health risks would increase. The author further states that treatment methods in current use leave certain pathogens in waste water. Cities such as New York are already investing so much in the cleanup of their water supply systems or estuaries (Esposito et. al. 2005).
Furthermore, public health officials suggest the placement of barriers as an effective method of protecting the masses form recycled water risks. One way would be preventing direct contact with contaminants. Therefore, it would almost retrogressive to use sewage effluent if it is already perceived as a health problem in many parts of the world.
Evidence from real-life cases is not sufficient to warrant consideration of recycled water for ingestion. Case studies on potable water reuse are few and hard to analyse. For instance, Anderson (2003) cites Orange County, in California, as one example. The county built a water reclamation plant that would treat water to drinking standard.
Not only did it employ a series of aquifers, but it also injected the water under high pressure. After fifteen years of intensive work, the recycled water was still not used for drinking. Po et. al. (2003) also talks about the controversies involved in portable reuse. For instance, Singapore worked on a project known as NEWater. The government wanted the project to curb dependence on other countries for water supply.
The Singaporean government even packaged the commodity in bottles such that the public could drink it conveniently. However, this plan did not work as few were willing to drink it. While the failure of the project failed due to public squeamishness towards the product, it still denied advocates of recycled water for potable use from having a tangible case study that could support their stand. Sometimes politics may come in the way of successful implementation of such projects.
Scientific backing may exist to support the safety of a water reclamation project. However, if lobbyists and other political groups undermine the implementation of the scheme, then one cannot study the immediate and long term effects of ingesting recycled water. As a result, it is not possible to make conclusive statements about the project. Namibia is a recurrent case study in water recycling analyses.
The city has been consuming recycled water from as far back as 1968. However, people rarely use recycled water directly in this country. Residents prefer blending the recycled water with conventional water. Sometimes the blend may be as high as 1:1 or may account for a quarter of the system in use (Anderson 2003). Direct portable reuse is not widespread because it requires transportation of recycled water from treatment plants into people’s homes.
The public and the scientific community are still not certain about the rigors of the treatment process. Therefore, many of them prefer to go for the indirect potable route (Marks et. al. 2006). If the pioneer of recycled water for potable use (Namibia) still cannot place all their confidence in reclaimed water, then one should question the plausibility of using the product for personal and human consumption.
Conclusion
Recycled water is not safe for drinking because of the health risks involved. Conventional treatment methods do not eliminate all microbes or chemical contaminants, and this could be dangerous. Additionally, few case studies exist to analyse the long term effect of 100% use (without blending) of recycled water among the masses.
Therefore, one cannot employ the method without support from conventional treatment systems. Finally, deliberate introduction of wastewater into water supply systems would increase the number of contaminants that require eradication, and this would pose a greater health risk than contaminated downstream water. Unless stakeholders eradicate these bottlenecks, then recycled water should not be treated as safe for drinking.
References
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Ashbolt, N 2004 ‘Microbial contamination of drinking water and disease outcomes in developing regions’, Technology, vol. 198 no. 3, pp. 229-238.
DTI 200 ‘Water recycling and reuse in Singapore and Australia’, DTI Global Watch Mission Report, November, p. 1-79.
Esposito, K, Tsuchihashi, R, Anderson, J & Selstrom, J 2005, ‘The role of water reclamation in water resources management in the 21st Century’, Water Environment, vol. 101 no. 4, 8621-8635.
Jimenez, B & Chavez, A 2004, ‘Quality assessment of potential use of an aquifer recharged with wastewater’, Water Science Technology, vol. 50 no. 2, pp. 269-76.
Marks, J, Martin, B & Zadoroznyi, M 2006, ‘Acceptance of water recycling in Australia: national baseline data’, Water, March, p. 152-159.
Morud, J 2009, Reclamation and reuse of wastewater, IUP, Iowa.
Po, M, Kaercher, D & Nancarrow, B 2003, ‘Literature review of factors influencing public perceptions of water reuse’, CSIRO Land and Water Technical Report, vol. 54 no. 3, pp. 1-33.
Steyn, M, Jagals, P & Genthe, B 2004, ‘Assessment of microbial infection risks posed by ingestion of water during domestic water use and full contact recreation in a mid southern African region’, Water Science and Technology, vol. 50 no. 1, pp. 301-308.
Toze, S 2006, ‘Water reuse and health risks-real vs. Perceived’, Desalination, vol. 187 no. 8, pp. 41-51.