It is the natural resource most essential to life, and yet, by and large, we tend to take it for granted. But, worldwide, some 783 million people lack access to clean water, and in many parts of the globe future supplies are under threat. In this Environment Week Making the Change special, we explore the world’s key sources of water, why they are under threat, and how we can take steps to prevent water waste and misuse.
Not all the water that we use for drinking, washing and irrigation falls directly from the sky. Deep beneath the Earth, in many different places, lie vast underground reserves of ancient water that naturally contribute to the water table and have been drawn on for centuries through the digging of wells to deliver much-needed replenishment to arid parts. But in today’s industrialised world, huge quantities of water can be pumped, for agriculture especially, and there is a danger that such resources will be depleted faster than they can be renewed, and eventually run out altogether.
The signs of aquifer depletion are obvious. As the water table is lowered, plants that formerly drew on this resource lose access to it, and may wither and die. Wells that formerly provided drinking water must be dug deeper, at great cost, or else locals will go thirsty. Streams and rivers that draw on the aquifers diminish in flow, and the surface layers of the ground itself can collapse as a cavern opens beneath them. Meanwhile, salt water may be drawn in through underground permeation from the sea in coastal areas, so that the soil becomes too salinized to use. Ultimately, the source of all life in an area with little rainfall – the aquifer – literally dries up, resulting in a crisis. For this reason it is vital that we do not rely too heavily on aquifers that aren’t rapidly renewed.
Parts of the world where aquifer depletion is an immediate threat include:
- Ogallala Aquifer, USA: supplying fresh water to many southern states, the aquifer has been pumped for irrigation since 1911, but is now so heavily drawn on that 6% is lost every 25 years; how long the supply will remain accessible in any given place is unclear
- Mexico City, Mexico: the city relies entirely on its aquifer, but depletion is so great that parts of the ground have begun to subside, and there is a risk that sewage systems could become damaged and mingle with the fresh water
- China: Ground water depletion is so severe that the Yellow River no longer reaches its mouth for many months of the year, making irrigation difficult for farmers
- Southern Europe, North Africa and The Middle East: Yemen, Iran, Spain and Egypt all draw on dwindling aquifers for their crop irrigation systems rather than relying on traditional water systems, partly because of increased demand for food to export to the west; the ‘Great Man Made River’ project in Libya threatens to undermine the Nubian Sandstone Aquifer system, the largest in the world
- Miami and New Jersey, USA: both coastal areas suffer from salinization of their aquifers as a result of over-pumping
Rivers are our most obvious direct source of water. Diverting or damming them for hydroelectricity or irrigation can have profound consequences on the local environment and the people living in it. Most of the more than a billion people living in and around the Indian subcontinent rely on the rivers of the Tibetan plateau for their drinking, washing and farming, so diverting and diminishing these rivers to feed larger farms, cities and power plants upstream has huge consequences. Plans to dam rivers such as the Irrawaddy, Brahmaputra and Mekong in China to produce hydroelectricity are causing disputes with countries downstream such as India and Vietnam, which could see the ecosystems upon which their human populations and a plethora of plants and animals depend destroyed and their farmland left without irrigation if the natural flow of the rivers is disrupted.
In light of these problems with water supplies, it is shocking that the western world continues to waste so much of the fresh water we have. Once river or aquifer water has been used and contaminated, it is returned, via treatment plants, to the rivers and flushed out to sea, becoming saline and thereby useless for most human activities except by expending vast amounts of energy in desalination. Hence, it is important that we don’t draw too heavily on our water sources. This is a particular issue in countries with a drier climate than that of the UK, but even here wasting water results in higher energy use as it must be passed through treatment works and reservoirs can be easily depleted in a drought. Furthermore, by changing our actions in a part of the world where it is easy to do so can help to set a good example for the rest of the globe, where following in the current ways of the west may result in water disaster. Here are some ways in which we can help:
- 30% of household water in the UK is used in flushing toilets; dual-flush systems, placing a brick in the cistern and avoiding excessive flushing can make a big impact on water usage
- Much of the fruit and vegetable matter we eat in the UK is imported from Spain or North Africa, grown using water directly drawn from diminishing aquifers; save water in these parts of the world and energy at the same time by buying foods grown locally and that are in-season, and reduce the amount of food you waste
- Grow plants that are suited to your local climate, and don’t require excessive watering, and use a watering can not a hose; let your lawn go temporarily brown rather than watering it in dry weather – it will recover
- Limit the amount of time you spend in the shower to at most five minutes, and don’t leave the tap running when you brush your teeth
- Reduce, reuse and recycle goods and food – the less we have to produce, the less water is needed for manufacturing and growing
- Don’t buy unnecessary clothes – each kilogram of cotton requires 20,000 litres of water to produce
- Only use dishwashers and washing machines on full loads and avoid pre-rinses
- Use a lid on your saucepan so that less water boils away and only fill the kettle with what’s needed
All of these things can either actually make our lives easier or have a neutral impact on our wellbeing, and save energy as well as water. On a larger scale, actions such as replenishing aquifers during wetter weather and using less water-intensive agricultural and production methods in areas where aquifer depletion is a problem can also help to avert potential disaster. With the world’s population increasing, however, protecting this vital resource must remain amongst our top priorities. Globally, fresh water is a more endangered resource than we, in often-rainy Britain, are sometimes inclined to think.