La planète peut-elle vraiment manquer d'eau?

Traduction française pour cet article à ajouter

On March 22nd we celebrate World Water Day to remember that water is one of the most valuable resources for life. We regularly hear that we will soon run out of freshwater, but what does that mean exactly: can the Earth run out of water? How does clean water get to our homes? What can we do to help? This article addresses these three questions while focusing on urban residential consumption.

The 2021 World Water Day campaign theme focuses on what water means to you and how you and your community can better protect this vital resource. Everyone is invited to join in on the conversation by sharing their views and ‘water story’ on social media, using the hashtags #WorldWaterDay and #Water2Me.

Question #1: Can the earth run out of water?

Water makes up about 70% of the earth’s surface. It exists as icebergs, flowing water, in the air we breathe, and in every living thing. It is said that the amount of water on Earth has always been constant since it was formed. Water evolves an endless circuit of evaporation and precipitation between the ocean, the sky and back to the land. That is why The Environmental Protection Agency (EPA) states that “the water from your faucet could contain molecules that dinosaurs drank.”

This stable amount of water on the planet — 332.5 million cubic miles of water — means that we cannot run out of water, per se. However, of all the water in the world, more than 97% is saltwater, and therefore undrinkable by humans. The remaining 3% is freshwater, but 2% of it is trapped inside ice caps: “That leaves just 1% for all of humanity’s needs — all its agricultural, residential, manufacturing, community, and personal needs.” (Source: EPA)

Today, whenever the desire to take a shower, drink coffee, do the dishes or run a load of laundry presents itself, water is at the tip of our fingers. We just need to turn on the faucet for an endless supply, a luxury not available for most of the world. In a metropolitan life-style, the demand multiplied by the number of people is overstretching the ability of water systems to meet our needs.


"A minimum of 20 liters of water per day per person is recommended to meet basic hydration and personal hygiene needs.” (Source: Organisation mondiale de la Santé)

“To live decently, a person needs 50 liters of water per day. For real comfort, a person needs about 100 liters daily.” (Source: Le centre d’information sur l’Eau)


US: 600 L/day/person
Canada: 500 L/day/person
France: 300 L/day/person
India: 150 L/day/person
Ghana: 30 L/day/person

Question #2: How does clean water get to our homes?

In nature, polluted water (by excrement for example) undergoes a natural cleaning process including evaporation and filtration through various sediments. This slow cleansing transformation can take up to three years in the wilderness. 

If nature’s organic regeneration time is not fast enough to answer our needs, it is in engineering that the solution is found. The first great aquatic engineers were the Romans, who managed to bring water through aqueducts. It is in the 19th century, engineers designed the first treatment plants.

In urban cities, water treatment plants have become part of the water cycle. It takes about 4 hours for a drop of water to make it through the treatment plant. The four main steps are: NATURE → Drinking Water Treatment Plant → HOUSE → Wastewater Treatment Plant → NATURE


Water is extracted from the river. It passes through various mechanical, biological, and chemical steps to finally be send through the pips to reach our homes.


5% Personal Hydration 
5% Cooking 
10% Leaks
10% House cleaning 
20% Landry
50% Personal Hygiene (toilet, shower, bath)


When water goes into our pipes, it is sent back to the treatment plant where it undergoes cleaning steps again before being discharged into the river.

Each municipality and country has its own infrastructure. Some cities around the world do not have a wastewater treatment plant. The UN reports that 80% of wastewater flows back to the ecosystem without treatment. Unfortunately, the infrastructure in each place depends on the municipality's economic situation: the richer the city, the more robust the water treatment system (map of Wastewater production, collection, treatment, and reuse status by countries and economies).


1. Check out the water treatment plants in your own city to find out the source that supplies your daily water consumption. 
2. Inquire about your local water treatment plant’s purification processes, and ask what you can do to help out and make a difference.
3. Help to educate others by sharing your knowledge with members of your local community.

Question #3: What can we do to care for our water at home? 8 accessible tips!

Taking care of the environment starts at home with a few simple steps. One can have an impact on the quantity of water they use at home by finding solutions to reduce their consumption. Quality is also crucial, as some products cannot be filtered by treatment plants. Here are some tips on how to be more ‘water-wise’ at home both in terms of quantity and quality:

1 - Turn off the faucets: 
Instead of letting your water run while brushing your teeth, fill up a glass of water. Similarly while doing the dishes, fill up the sink. Likewise, to clean up your fruits or vegetables, fill up a large bowl. 

2 - Use every drop: 
When you run the tap to find the right temperature, place a bucket or a jar below the faucet and reuse what you’ve gathered to water your plants or do the dishes later. If you want to go one step further, reuse the water from your shower and washing machine for mopping the floor and flushing the toilets. 

3 - Invest in solutions
Buy a water aerator for your sink that will help you reduce the amount of water from your tap without losing the washing efficiency. In the shower, mount a water-saving showerhead. In the bathroom, install a low-flow toilet. Consider getting a front-loading machine as it uses less water than top-loading ones.

4 - Harvest rainwater: 
India is one of the countries well known for its rainwater collection techniques. The use of ponds, water pits or simply a tank on top of a building are great practical ways to collect rainwater to reduce the freshwater stress and water costs, especially where the tap might run dry during the hot season.

“A drop of water, if it could write out its own history, would explain the universe to us.” – Lucy Larcom (poetess)

5 - Use eco-friendly products:
Whether cleaning the house, while in the kitchen, laundry room or bathroom, use organic eco-friendly products that will not harm the environment. 

6 - Dispose of medication properly:
Do not flush expired medications. Also, before turning to conventional drugs to solve medical issues, first try to find a cure using natural remedies and homeopathy. Note, that even if drugs are not disposed of directly down the drain, they can still contaminate the water by passing through your urine and sweat

7 - Choose organic:
Buy organic fruits and vegetables to avoid pesticide residue leaking into our water from washing them.

8 - Become more aware:
A great exercise is to consciously observe your water consumption throughout a regular day. Every time you open a tap, observe how much water you are using, for what, and what you let flow down the drain. You will see that this attitude will intuitively lead you to find solutions on your own.

“We must make every effort to protect our oceans and marine life by being conscious of what we flush into our water systems. What goes down a sink, toilet, or storm drain may end up in our rivers and oceans. Only flush chemical-free biological waste. Solid, non-biodegradable objects must be discarded so that they cannot pollute and degrade our waters.” — Dax Dasilva, Age of Union: Ingniting the Changemaker


Photo credit in order - from the 
Unsplash platform:
Bibi Pace
Jack Anstey
Bluewater Globe
Marc Zimmer
Mario Alvarez