Why Is Water Considered a Renewable Resource?
Water is our planet’s life-giving force. Together with the Sun, our water resources help sustain a great diversity of plants, crops and animals across the globe, all living in very different environments, from frosty Antarctica to temperate and tropical regions. Our planet is 70% water, with the largest part of this water body being oceans [1], so this creates the illusion that water is abundant.
However, in reality, only 3% of our planet’s water can be used for drinking, irrigation and other very important uses for both humans and nature [2]; and of that about two thirds are frozen in ice caps and glaciers. 22% of our planet’s water resources are used by industry [2], whereas our own personal water footprint, i.e. our consumption and use of water, has steadily increased.
And yet, not everyone has access to the water they need. Water pollution and scarcity are affecting many communities globally. About 250 million people die each year from diseases linked to water pollution while 2.5 billion don’t have access to improved sanitation. What is more, it is projected that by 2025, 3.5 billion people will face water shortages due to water pollution [1].
How can water be a renewable resource if we are facing so many problems of its scarcity?
First of all, it is important to start off with a clear understanding of what a renewable resource is. Today we are inundated with so many different types of renewable resources particularly different types of renewable energy resources, of which one is hydro, that it is important to clarify the term renewable itself.
What is a renewable resource?
A renewable resource is one that can replenish itself either biologically or otherwise and thereby overcome any scarcity concerns. Time or rather how long it takes for the resource to replenish itself is an important consideration to determining its potential as a renewable material.
For example, timber is considered a renewable material as it takes about 25 years until a tree can be felled [3]. If our activities do not respect this time limit of plant regrowth, then timber ceases to be renewable, in a practical sense, as we would be using it much faster than it can naturally replenish itself.
Water cycle
In the case of water, it could be argued that water is a renewable material on account of the processes of the water cycle. Water evaporates from the Earth’s surface and goes up into the atmosphere where it condenses. It then falls back onto the Earth as rain or snow and is deposited in rivers, lakes, porous rock and the ocean.
The water will then once more begin the same cycle by evaporating from the Earth’s surface. Water can stay in the atmosphere for up to 9 days, but it can stay in a river for up to 6 months and up to hundreds of years in lakes or the ocean [4].
So water is renewable in that it completes a cycle: water leaves the Earth but it also re-enters it.
But just like with timber, our activities impact the availability of water and its quality despite the water cycle and water’s natural ability to renew itself. We use a lot more water in our daily lives and a lot of the water we use cannot be reused because we have polluted it. As such, our water resources are being depleted at such a high rate that despite the water cycle, we will face increasing limitations on our water supply.
So while water can be considered renewable given its natural life cycle, in our daily life we should consider it a precious and limited resource. This is not only because drinking water is a tiny fraction or the water bodies on our planet, but also because we need to be mindful that human activities such as industrial production, agriculture, waste disposal and many others are polluting our environment and water.
We should not consider that water is a renewable and therefore inexhaustible resource, we should rather acknowledge the importance of ensuring that the quality and quantity of water remains such that the natural water cycle can continue undisrupted, despite ongoing human activities.
References
[1] https://goo.gl/u16jqs
[2] https://en.m.wikipedia.org/wiki/Renewable_resource
[3] http://www.technologystudent.com/prddes1/susenv1.html
[4] https://scied.ucar.edu/longcontent/water-cycle
