- What is water used for?
- Where does the used water go?
- Why is it necessary to use water sparingly?
We use water on a daily basis
Water is an irreplaceable natural resource that all organisms need. We have to share the little freshwater we have in the world with plants and animals, for whom water is also essential. We use water every day, both at school and at home. Water is used to irrigate park trees and lawns, wash streets and put out fires, and it is also used in saunas and swimming pools.
The largest water users in the world are agriculture, industry and households. It generally takes little water to irrigate fields and gardens in colder climates because it usually rains enough in summer. Still, in warmer and drier climates, it is necessary to irrigate crops regularly. Large greenhouses use a lot of water; livestock needs drinking water and washing water for the stables. The industry also consumes a lot of water. Making many things is not conceivable without clean water. In a power plant built on a river, running or falling water spins the wheels called turbines, which starts a generator that produces electricity.
Bonus: How much water do we use every day?
Activity |
Water consumption |
Taking a bath |
120–160 l |
Taking a shower |
80–120 l |
Washing dishes |
30–80 l |
Using the toilet |
20–25 l |
Find out how a dripping or broken tap or water pipe affects water consumption. To do this, you need a 1‑litre container and a stopwatch. Only open the tap enough for the water to drip out. Measure how long it takes to fill the container with water. Calculate the water consumption per hour and per day.
Think!
- Why do you need water every day, and how much do you need it?
- Industry
- Agriculture
- Public drinking fountains
- Households
Where do we get our drinking water?
Drinking water can be obtained from groundwater, a lake, or a river. In many places, water reservoirs are constructed on rivers to supply people with drinking water. Water that originates from rivers and lakes is not always clean. Therefore, it needs to be purified before it reaches our homes.
To access groundwater, deep boreholes need to be built. Although groundwater is usually quite clean, it still needs to be treated before it can be used as drinking water. Care must be taken to ensure that no water-polluting substances enter the wells and groundwater from the ground.
In rural communities, drinking water is usually obtained from a well. A deep hole is dug in the ground to build the well, the edges of which are lined with concrete manhole rings to prevent collapse. Water seeps from the groundwater to the bottom of the well. The amount of water in the well depends on the amount of rainwater that sinks into the ground around the well.
Bonus: Bottled water, or tap water?
Tap water is more fresh than bottled water, because bottled water can stay in a plastic bottle for several years, but the tap water changes at least every day. However, bottled water is much more expensive than tap water. In addition, drinking tap water is much more environmentally friendly.
Think!
- Why could there be a shortage of water in your hometown?
- How can you save water during a water shortage? Is it better to take a shower or a bath at this time?
- River and lake water
- Seawater
- Groundwater
- Rainwater
What is wastewater?
Water leaving buildings through sewers is polluted. Water used by humans is called wastewater. Both food residues and various detergents are dissolved in this water. In the past, wastewater was discharged directly into a river or poured down under a bush to infiltrate the ground. Eventually, the polluted water flowed into the sea, making the water muddy and often smelly. Currently, most of the wastewater generated in households ends up in water treatment plants.
- Taking a shower
- Irrigation with rainwater
- Washing a car
- Drinking water
- Washing dishes
Think!
- How does the growth of cities affect the groundwater properties?
- How do people take care of the cleanliness of the water in your home town?
How does a wastewater treatment plant work?
Today, strict regulation is put in place to ensure that wastewater and industrial toxins do not enter the water cycle. Sewage treatment plants have been built in cities and larger settlements. All factories must also treat used water.
Water is collected at the water treatment plant, and larger solids are screened and strained out of the water. Substances that kill pathogens are then added to the wastewater, as well as bacteria that feed on the organic matter in the wastewater. For bacteria to better break down harmful substances, air is pumped into wastewater to add enough oxygen. After that, the water is settled, i.e. the sand and mud are allowed to sink to the bottom. Finally, the water is filtered to remove the last solid, insoluble particles. The treated water is pumped into nature – either into a lake, river or sea.
- Filtration
- Settling
- Addition of different chemicals and bacteria
- Straining
- Pumping air into the wastewater
Think!
- What happens to the water that flows down the sink?
- Why do we have to use water sparingly, even if we live in a place where water is abundant?
Pollutants enter water from the industry and elsewhere
Toxic chemicals and fertilisers flow from the fields into rivers, lakes, and bays, along with rainwater and snowmelt. In the past, many factories discharged their wastewater and toxic waste directly into the water. Due to accidents, ignorance, or negligence, pollutants still enter the bodies of water. When fertiliser residues and polluted water reach the water body, algae and plants start to grow excessively. This will ruin the living conditions for other aquatic organisms, because after the algae and plants die, they use up all the oxygen to decompose, leading to a lack of oxygen in the water. This creates dead zones, where no aquatic life can survive.
- Too many nutrients get into the water, and the plants and algae start to grow excessively.
- Toxic chemicals get into the water.
- Due to the excessive growth of plants, the diversity of animals increases as well, and there is no longer enough food for everyone.
- Decomposing dead plants requires a lot of oxygen, and this may lead to lack a of oxygen in the water.
Bodies of water can self-clean
Water bodies have the ability to clean themselves. You must have seen dead fish in a lake or at the seashore. They decompose like the remains of other dead aquatic animals and plants, yet the water stays clean and clear. But sometimes so many pollutants get into the water that the water body cannot clean itself anymore. In addition, some substances break down very slowly in nature. Even more dangerous are the substances that do not break down in nature at all.
- Yes, because water bodies have a self-cleaning capacity.
- No, because some substances do not break down in nature at all or take a very long time to break down.
Important terms
- drinking water – water that is suitable for drinking
- settling – the process by which solids settle to the bottom of a liquid
- straining – pouring a liquid through a material or a device that separates out any solid matter
- filtration – the process of removing the fine particles in water by filters
- wastewater – water that has been used by humans and that is no longer clean
I now know that…
Humans use a lot water in the households, industry and agriculture. The water that has been used by humans and that is no longer clean is called wastewater. Wastewater is treated in water treatment plants. Drinking water is obtained from groundwater, but also from lakes and rivers.
