Water is a renewable resource. But there is a danger that we might not have enough supply by the 21st century because of over-extraction and possible contamination of aquifers. If we mismanage the natural systems that provide us with fresh water, we will be making water unsustainable in the long run.
You might find me ridiculous when I say we might run out of water by the 21st century. What I’m referring here, though, is clean potable water.
Yes, it is true that the earth is literally a world of water. We use it in so many ways. It is more than just a drink. We use it for agriculture, for industry, and for energy.
Also, water is a renewable resource in the sense that it is powered by the sun, which vaporizes water from the oceans and other different bodies. Through gravity, the vaporized water cycles and falls back to earth as precipitation. Some of these water come as rain or snow.
However, worldwide precipitation is not the same in all parts of the world. Some regions are water-rich in the sense that they get enormous fluxes, or flows, of water; while some places are water-poor, where they get low fluxes. There are also places where there is a significant stock of water.
There’s also another huge resource of water – underground, or in what we call aquifers. We tap into this source of fresh water for use in agriculture, energy, industry, or for human consumption. The water we extract from aquifers gives us a sense of how much water we can sustainably use each year.
We know that the stock of water underneath the ground takes a very long time to accumulate. In some areas, aquifers are even thousands of years old. If we just use fluxes for our different needs, we would not encounter major sustainability problems, since the water we take out would be replenished each year. However, sustainability issues can come in when we take out too much water from these sources faster than it gets replenished.
Agriculture is the single major user of water worldwide. Water loss during agricultural processes is so much more of a problem than water loss in the home. But I’m not saying, either, that it’s all right for us to not conserve water domestically. What I mean is that domestic use of water is just a small part of total use, and it is often highly treated, making it a special case of water.
Large countries, like China and India, are known to have been over-extracting fresh water for their intensive agriculture, as well as for consumption of their huge populace. Other countries and regions, too, have reached a dangerously low water tables and are experiencing water stress.
This concerns the water in the natural system, or that which is part of a hydrologic cycle. Water stress refers to the amount of water required to make a product.
The illustration below shows the amount of irrigation water, or embedded water, used to produce common consumer products. A cup of coffee, for example, requires about 200 liters of water to produce. How does it happen?
Well, computation starts from the growing of the coffee plant itself. To cultivate coffee, you’ll need a lot of precipitation and irrigation before the beans were ground up, and brewed. So that’s how we come up with the 200 liters to make a cup of your favorite drink.
Now, the processing and production of coffee is done and brought to supermarket shelves. You bought a pack of that coffee and prepare it at home. Then you add about 250 milliliters of water to dissolve your coffee. Obviously, you didn’t use as much water on it as the agricultural processes did. This is what I mean by domestic use of water is so much less than what is used for agriculture. The same holds true in the production of the other products listed in the illustration, as well as in the manufacture of a car, or an aluminum can.
Another threat to water is pollution. Water pollution contributes much in the scarcity of clean water in the world today, making it unsustainable. Scientists even predict that we might be facing severe shortage of fresh water by the 21st century if we don’t properly manage what we have at present.
Water can be polluted in so many ways. Both industrial and agricultural processes can pollute the water sources. When an aquifer is polluted with heavy metals or organic compounds that cause cancer, that resource can no longer be used.
So, if we truly value the natural world, we must minimize the total amount of water that we extract, so that the natural systems will constantly have enough to provide us with.