Hello there, my name is Mr. Wilshire, and in this lesson we're going to be looking at how we can provide safe drinking water.

The outcome for this lesson is I can investigate natural ways to filter dirty water.

There are some keywords for us to remember as we work our way through this lesson.

The very first is access.

Next, microorganism.

After that, filter.

Finally, natural.

Don't worry if you're not too sure what some of these words mean.

You can pause the video here and have a recap.

Restart the video when you've done that.

The first part of this lesson is called, Access to drinking water.

We all need water.

Here you can see a picture of a tap, and Izzy says, "Well, we collect rainwater to water our plants." Alex says, "I use water to wash and to brush my teeth." What else do you use water for? Have a quick think.

Pause the video and discuss.

Restart when you've done that.

So what did you think of? Are there any other ways that you can use water? Oh, what about washing the car? You might decide to wash your car using water.

I wonder what else you said.

We use water for all sorts of things.

Did you say any of these? You could have said some of them, maybe washing up or flushing the toilet, cleaning your teeth, or watering plants, drinking, cooking, maybe washing clothes, or even washing yourself.

So have a think.

Which of these do you think is the most important? Pause the video here and discuss.

Restart when you've done that.

So which of these is the most important, do you think? Well, water is a very basic need of all living things.

We need water to drink to survive.

Without water, there wouldn't be any life, would there? Jun says, "The water I use is cleaned by a local water treatment company, so it's safe to drink when I turn on the tap." Izzy says, "Does everyone else in the world have access to safe drinking water?" Hmm, I wonder, what do you think? Does everyone in the world have that access? Pause the video and discuss.

Restart when you've done that.

What did you think? Does everybody all over the world have this access? Let's find out.

Only around 80% of the world's population have access to safe drinking water at home.

This is about 80 out of every 100 people in the world.

The other 20% don't have access to safe water to drink.

Alex says, "Wow, that means approximately 1.

6 billion people in the world today don't have water that's safe to drink." Oh dear, that's not very good, is it? I wonder how they survive.

Let's stop and think.

What percentage of the world's population has access to safe drinking water at home? Is it 20%, 80%, 60%, or 40%? The correct answer here is B, 80%.

80% of the world's population has access to safe drinking water at home.

Now, the water we drink needs to be clean, otherwise it can make us ill.

You may have seen before that microorganisms can live in water.

They can only be seen through microscopes, so you've no idea that you're drinking them.

This can really upset your stomach.

Unsafe drinking water is one of the world's largest health and environmental problems, particularly for the poorest people in the world.

Alex says, "How can water be unsafe to drink? It always looks so clean when it comes out of the tap." Hmm, use the knowledge that you've learned so far and think how can water be unsafe to drink? Did you have a good think? Remember, microorganisms are one of the reasons.

Are there any other reasons? Some people living in poorer areas around the world rely on water from rivers, lakes, or shallow wells where the water is not safe to drink.

Here you can see a child carrying water from a well.

If they've got to go there to get water, sometimes it can be a very long distance for them, and everybody in the family would be expected to help.

Unsafe water can contain solid materials including litter, sediment, and other debris from soil erosion.

So what else might water have in it that makes it very unsafe to drink? Well, often there is sewage in river water.

There are likely to be washing products as well, polluting water.

Some people don't have running water in their homes, so they're unable to use a washing machine or a dryer.

This means that they would often go to the river to wash all their clothes.

If that river is fresh water, that's okay, but if everybody is doing it, that's going to slowly pollute the water.

If everybody is cleaning their clothes in the water using soap, that water is going to end up turning very soapy.

And if some people downstream then have to use that water to drink, it's going to make them feel very unwell from drinking soapy, horrible water.

They could also be some liquid waste from local industry.

Many factories and warehouses have pipes that go out into the rivers in order to dump waste.

If this isn't regulated and kept an eye on, then often those rivers can become swampy, sewagey dumps.

How horrible! June says, "Water can also contain tiny living things called microorganisms that we can't see, but they can make water unsafe to drink and cause a stomach upset." We've already talked about these, haven't we? And I know that we've seen them before.

You can only see them with a microscope.

Izzy says, "Bacteria and viruses are microorganisms. They may be found in water." These microorganisms really thrive in these kind of wet environments.

Humans rely on many helpful microorganisms to be healthy, but harmful microorganisms can make us ill.

So microorganisms are all around us, so it could be in our food or the water that we drink.

It doesn't necessarily mean that they're always going to make us ill.

Some of them can actually be good for our bodies.

Let's stop and think.

Unsafe, blank, is one of the world's largest health and environmental problems, particularly for the poorest in the world.

Is it roads, electricity, food, or water? The correct answer here is water.

Unsafe water is one of the world's largest health and environmental problems, particularly for the poorest in the world.

Here is Task A.

You need to talk with a partner to decide who you agree with and why.

Do you agree with Jun? "I think everyone in the world has access to safe drinking water.

They just need to turn on the tap and there's enough water for everyone." Or do you agree with Izzy? "Not everyone has access to safe drinking water.

Just because water comes out of a tap, this does not always mean that it's safe to drink." Hmm.

Have a discussion here.

Who do you agree with and why? Restart the video when you've done that.

How did you get on, and who do you agree with? Well, Izzy is correct.

She said, "Not everyone has access to safe drinking water.

Just because the water comes out of a tap, this does not always mean that it's safe to drink." In many countries, people will rely actually on bottled water, but this in turn can have a bit of an adverse effect, because if they don't know where to put those bottles to recycle them, those bottles may end up floating down the river too.

Around 1.

6 billion people living today don't have access to safe drinking water.

Some people living in poorer areas around the world rely on water from rivers, lakes, or shallow wells where water is not safe to drink.

Hopefully, you said something along the same lines as this.

Well done for completing that task.

The final part of our lesson is called: Filtering dirty water.

Some people may have to walk very long distances to collect water, and sometimes the water they collect is not clean.

Here you can see an example of a water pump.

This is where you need to pump water out of the ground, especially if there's a pipe going into the ground to collect the water, out of a well, for example.

So I wonder then, is there a way to make dirty water clean and safe to drink? What do you think here? And Izzy says, "Could you add some soap to make it drinkable?" Hmm, what do you think? Pause the video and discuss.

Restart when you've done that.

So what did you discuss? Is adding soap going to help here? Alex says, "Scientists use filtering to separate insoluble solids from liquids." Here you can see an example of a filtering experiment in a lab.

But Alex continues, he says, "But families living without access to clean water are unlikely to have access to filtering equipment." Hmm, yes, you're more than likely to find filter paper in a lab.

How could you filter water using natural materials? Have a quick discussion.

Reset the video when you've done that.

So what kind of natural materials could you use to filter water? Let's find out more.

Natural materials, like gravel and moss, can be used to filter water.

They can then remove larger solid particles.

Izzy says, "Wouldn't gravel and moss make the water dirtier?" Well, scientists and engineers were inspired by nature.

They observed that gravel traps sticks, soil, and other waste at the bottom of streams and rivers.

If you've ever seen a gardener digging a trench, sometimes they put gravel in the bottom of the trench to help water to flow away from their garden.

This can help to irrigate the land.

Similar to this, though, moss, a soft plant, traps soil and lets the water flow through it.

Natural filters help keep our fresh water clean without using added ingredients or machines that require electricity.

Sand, gravel, coconut shell, and peat moss are all examples of this.

Ground charcoal is used as a natural filter too.

It can even remove smells from unsafe water.

Hmm.

If you are using unsafe water in this way, often it's called grey water, and usually it could be very, very smelly, ugh.

Stop and think.

Is this true or false? Scientists and engineers are inspired by nature to create filter systems for water.

The correct answer here is, true.

Can we justify our answer? Which of these statements best match? The correct answer is B.

Some natural materials, like gravel and moss, can filter out small pieces or particles from water.

So, filtering removes insoluble solids from dirty water.

However, it could still contain dissolved and liquid materials like sewage, washing products and liquid waste.

This can be washed into rivers from homes, farming, and industry.

So, before, when we were asked if using soap is gonna help clean water, that wasn't a good idea, was it? Even when water looks clean, water may still contain harmful materials that we just cannot see.

You can only see them with a microscope.

Microorganisms are very tiny living things which are so small that we can't see them without using the microscope.

And if we drink water containing these, we can become really ill.

For example, diarrhoea and vomiting can be caused by these microorganisms. Once insoluble solids have been removed from water, it must undergo further treatment to make it safe to drink.

This can include the addition of chemicals or treatment with ultraviolet light.

This then kills off the microorganisms. You can see an image there of a microorganism that's been taken through a microscope.

I don't think I'd really want that swimming around inside my body, ugh.

Here is Task B.

Step one, you're going to make a natural filter to remove large insoluble particles from dirty water.

The first part here is to safely cut the bottom of a plastic bottle.

You're then going to put a plug of cotton wool in the bottom of this bottle.

Put about three centimetres of sand on top of the cotton wool, and then you're gonna put about three centimetres of gravel on top of the sand.

Then, you need to test your filter.

First take the lid off your bottle, then hold it over a cup or a bowl.

Finally, pour some dirty water into the open end of the bottle, and watch it run through into the cup or bowl.

Now, here's a warning.

Don't attempt to drink the filtered water, even if it looks clean.

We can't be sure if it's really safe to drink.

You can see an image there of somebody doing this experiment.

So, follow these two different steps.

Best of luck.

Reset the video when you've done that.

How did you get on? Your filtered water may have ended up looking a little bit like this.

Were you able to remove some of the larger particles from the water? What colour did it turn out underneath? Here is step two.

The water was definitely cleaner after going through the filter, but it still had a slight yellowish colour, but not very much.

But you can see it in the bottom of the cup there.

So all of that dirty water has travelled through all of those components.

Hmm, still dunno if I'd like to drink this.

You could see that grass and sticks have been trapped by the filter.

That's good, I don't really want to drink those.

This water would still need some more treatment to make it safe to drink.

Of course, you may need to use some special chemicals to then make sure that all those microorganisms are killed off.

Let's summarise our lesson.

Around 80% of the world's population have access to safe drinking water at home, leaving 1.

6 billion people without.

Unsafe water is one of the world's largest health and environmental problems, particularly for the poorest in the world.

Scientists and engineers take inspiration from nature to create filter systems to clean water for drinking.

Hopefully you can go on to use this knowledge to help the 20% of people in the world who don't have access to clean water.

It's a really big problem that needs to be solved.

Everyone deserves the right to live, and everyone deserves the right to clean water.

So, I wonder how you might go on in the future to help these people out.

I'm Mr. Wilshire, thank you very much for listening.