Urbanisation. Economic development. Unsustainable agriculture. These factors are causing problems with water quality and quantity all around the world, an issue which will likely only get worse unless we deal with the precious resource more responsibly. But is it water quantity or quality that deserves our more immediate attention?
Water quantity is certainly a critical future issue. With more than one billion people not having guaranteed access to drinking water today , it is predicted that by 2025 two thirds of the global population will live in areas of water stress . We will accordingly need to withdraw more freshwater – a staggering 38% more than in 1995 – partly because we need it to produce food for our growing population. Agriculture comprises as much as 75% of the total global water consumption, mostly through irrigation . Climate change will harshly affect agriculture by making extreme weather like droughts and downpours more common, which will not only dry crops out but also leave the soil more vulnerable to erosion. Moreover, climate change is expected to put further pressure on countries where irrigation requirements already exceed available water resources, such as India, Pakistan, or China , as shown by Figure 1.
To satisfy demand for water, cities resort to drawing freshwater from distant sources and transferring it, but this can have negative consequences; for instance, Lake Owens and Mono Lake which supplied Los Angeles  suffered from salinisation because they were overused. Although it is possible to tackle this issue by building large-scale engineering projects, improving demand management or implementing desalinisation mechanisms, these approaches are expensive and thus not suitable for all countries .
Water scarcity is especially a problem for rapidly expanding cities in arid climates because they put pressure on groundwater resources . Approximately 1.5 billion people depend on groundwater as their source of drinking water, and groundwater comprises 90% of the easily accessible freshwater reserves . Cities in arid regions often overexploit underground reservoirs, since these cannot renew quickly enough. For example, the Great Libyan Man-made River which draws water from ancient aquifers under the Sahara and transports it to the coast has stopped the flow of many springs. Mexico City, Bangkok and Beijing have even suffered from subsiding ground as a result of groundwater overexploitation, and there are reports of unsustainable groundwater use in North Africa, Middle East, and North America as well .
Since groundwater is so essential to people all over the world, yet its purification takes a long time, its pollution presents a huge future risk. Water and soil are containing increasingly more salts because of overusing irrigation and withdrawing too much groundwater and pollutants both from the surface and underground seep into aquifers. A large number of important urban aquifers are already polluted by organic pesticides, nitrates, heavy metals and waterborne pathogens . Surveys from India and Africa indicate that 20-50% of all wells have dangerously high nitrate concentrations . Because pollutants seep slowly through groundwater, it may be contaminated in the future even if we stop active pollution, and aquifers may not be usable for longer periods of time . Neither will we be able to remedy pollution by simply diluting it with freshwater because many countries are already using water resources fully .
Freshwater quality may also limit urban development and cause a decline in food production. At the same time, agriculture, together with urban runoff, significantly contribute to water pollution , already causing about 2 million deaths every year . Improved sanitation is financially demanding, which forces countries to dispose of sewage and factory run-off in unsustainable ways that can contaminate water resources . In the future, it will be even harder to provide water in urban areas as urban population is projected to increase by 1.5 billion people by 2030; almost 890 million are expected to suffer from poor water quality . Developing countries in particular are affected by this issue as they will increasingly need to draw water from groundwater and polluted surface water sources.
Water quality also suffers due to increasing water temperatures and runoff as a result of climate change. Even in the Global North, increased water temperatures will speed up biochemical processes and make algal blooms occur more often, causing problems for water treatment plants, reservoirs, and rivers, especially during summer . Water will evaporate faster in higher temperatures, which means that pollutants will be more concentrated in the water. The cost of water treatment will thus increase and will be more problematic . In developing countries, droughts and increased precipitation will increase the occurrence of water-borne diseases, and the presence of new micro-organisms will require treatment plants to undergo costly upgrades. During rainy seasons, a mixture of rainwater and sewage could flood urban areas.
As shown by the points above, the issues of water quality and quantity are both vital and it cannot be generalised that one will be a greater problem than the other. They are location-dependent and governed by the economic capacity of countries to respond to them. Vörösmarty et al.  have identified areas of threat to water security (Figure 2), which is a term incorporating issues of both water quality and quantity. Their analysis shows that the economic capabilities of countries are crucial to ensuring water security – like climate change, it is thus a problem of geographic and economic inequality. Developed countries are able to spend their way to water security while most of Africa and much of Asia have problems establishing fundamental water services .
Water security is our common global problem. Since most water is used for agriculture, it appears that a shift in production and consumption patterns is necessary to avoid a serious water crisis. However, consuming less water and using sustainable agricultural practices could lower crop yields and negatively impact the economy. While water purification technologies could help alleviate the problem, some think they are the equivalent of fixing with the left hand what we broke with the right and that a natural regeneration of water sources by halting economic development needs to take place. In any case, water issues are likely to remain on the top of our to-do list for the foreseeable future.
1. Koutsoyiannis, D. (2011) ‘Scale of water resources development and sustainability: small is beautiful, large is great’, Hydrological Sciences Journal, 56(4), 553-575.
2. United Nations Environment Programme (2008) Vital Water Graphics: An Overview of the State of the World’s Fresh and Marine Waters, 2nd edition [online resource]
3. Kemp, D.D. (2004) Exploring Environmental Issues, London ; New York, N.Y.: Routledge
4. McDonald, R.I., Douglas, I., Revenga, C., Hale R., Grimm, N., Grönwall, J., and Fekete, B. (2011) ‘Global Urban Growth and the Geography of Water Availability, Quality, and Delivery’, AMBIO (40), 437–446.
5. Cutter, S.L. and Renwick, W. H. (1999) Exploitation, conservation, preservation : a geographic perspective on natural resource use, 3rd edition, New York ; Chichester : John Wiley & Sons .
6. Ongley, E. (1996) Control of water pollution from agriculture – FAO irrigation and drainage paper 55 [online resource]
7. Bhattacharyya, K. G. and Kapil, N. (2010) ‘Impact of urbanization on the quality of water in a natural reservoir: a case study with the Deepor Beel in Guwahati city, India’, Water and Environment Journal (24), 83–96.
8. Thorne, O. and Ferner, R.A. (2011) ‘The impact of climate change on reservoir water quality and water treatment plant operations: a UK case study’ Water and Environment Journal (25), 74–87.
9. Kundzewicz, Z.W., Mata, L.J., Arnell, N.W., Döll, P., Kabat, P., Jiménez, B., Miller, K.A., Oki, T., Sen, Z., and Shiklomanov, I.A. (2007) ‘Freshwater resources and their management. Climate Change 2007: Impacts, Adaptation and Vulnerability’, in Parry, M.L., Canziani, O.F., Palutikof, J.P., van der Linden, P.J., and Hanson, C.E. (eds.) Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, UK.
10. Vörösmarty, C. J., McIntyre, P. B., Gessner, M. O., Dudgeon, D., Prusevich, A., Green, P., Glidden, S., Bunn, S. E., Sullivan, C. A., Reidy Liermann, C., and Davies, P. M. (2010) ‘Global threats to human water security and river biodiversity’, Nature (467), 555–561.
1. Koutsoyiannis. 2011. (Reference )
2. Vörösmarty et al. 2010. (Reference )
Peter Vaník is a final year Geography and Politics student at the University of Glasgow who would like to see more immediate effort put into solving long-term problems.