Write down a few words
describing this scene
What do you think?
From Science Concept Cartoons Set 2 – Millgate House Education
Why did NASA send Mars Rover
to find clues of water?
Water signifies life
Earth is the only planet we know that has water and
without it life on Earth could not have evolved
Where do you use water?
If a person in the UK had to carry home all their water in
2 litre bottles, on average, how many would they need
each day?
4 bottles
20 bottles
75 bottles
90 bottles
On average a person in the UK uses
150 litres of water = 75 two-litre bottles
So how many do you think an
average person in the USA would
use?
On average a person in the USA uses
575 Litres of water = 287.5 two-litre bottles
So how many do you think an
average person in Italy would use?
On average a person in Italy uses
386 litres of water = 193 two-litre bottles
So how many do you think an
average person in Bangladesh would
use?
On average a person in Bangladesh uses
46 litres of water = 23 two-litre bottles
So how many do you think an
average person in Ethiopia would
use?
On average a person in Ethiopia uses
15 litres of water = 7.5 two-litre bottles
So how many do you think an
average person in Mozambique
would use?
On average a person in Mozambique uses
4 litres of water = 2 two-litre bottles
The World Health Organisation say
that about 20 litres per person per
day is needed to take care of basic
hygiene and basic food hygiene.
Laundry/bathing might require
higher amounts.
Can you think of some sources of
water?
Artificial
Natural
Reservoir
River
Are these
accessible
to everyone?
Rain
Well
Lake
Rain water harvesting
Glacier
Over 1.1 billion people
DO NOT have access to
water
On average women
in Africa and Asia walk
3.75 kms to
collect water
https://www.youtube.com/watch?v=mVTahkpVabw
Over 2.2 million
people die each year
from a waterborne
disease
Do we have a water problem in the UK?
Do you remember - England and Wales drought
2010 to 2012?
00
Without
preventive action
this will only get
worse!
Daily Mail, 21st February 2012
Before we look at
ways to make water safe…
Let us think about
what makes water unsafe?
What makes water unsafe?
Untreated Rubbish
Oil leaks from ships
Dirt
Untreated sewage
CONTAMINANTS
pesticides
cadmium
copper
oil
mercury
lead
zinc
How can we remove these
contaminants?
Filtration
Removes large visible contaminant particles
 Separates materials of different composition
X Does not destroy any micro-organisms
Activity
Sedimentation
Gravity slowly causes the high density particles that contaminate the
water to settle out so they can then be easily separated.
 Particles (e.g. dirt, heavy metals, stone,
etc.) suspended in the water settle out
X Does not destroy any micro-organisms
Ozone disinfection
Using a molecule’s natural property to disinfect water
Ozone (O3) is an unstable
molecule. It readily gives up an
atom of oxygen (O) .
Single Oxygen atoms (O)
can destroy most toxic
waterborne organisms.
The only product left after the
process is Oxygen (O2)


Most harmful protozoa
Most pathogens
X
Does not prevent the water becoming
re-contaminated
Disinfecting using chemicals
A final stage of purification to kill microorganisms
invisible to the naked eye
IODINE
CHLORINE
 Most viruses and bacteria
 Remains active for a period of time
X Doesn’t destroy most protozoa
Boiling
 Destroys most bacteria
 Inactivates viruses
X
X
Doesn’t affect Prions (a form of protein)
Doesn’t affect some bacterial and
fungal spores
Most
effective
Ultraviolet treatment

X
Most bacteria
Does not prevent the water
becoming re-contaminated
Build a filter!
Activity
• Every team should have a ‘Country Sheet’ and ‘Cost’ sheet.
• Read the information for your country.
• Within your groups:
Plan and design your filter
Complete the ‘Cost sheet’ and nominate 1 member to
buy goods from the shop
Nominate 2 members to test and present the filter
Material
Unit Cost
2 litre bottle
10 credits
Straws
2 credits each
Rubber Band
2 credits each
Activated charcoal
30 credits per 1/4 cup
Cheesecloth
4 credits/square
Cotton wool
2 credits/ball
Gravel - coarse
5 credits/cup
Gravel - fine
5 credits/cup
Sugar
5 credits per cup
Toilet paper
1 credit per sheet
Sand- coarse
10 credits/cup
Sand - fine
15 credits/cup
A4 paper
2 credits per sheet
Information sheets
Fully Labelled Diagram
100 credits
Unlabelled diagram
50 credits
Full instructions (Available if your country has a
literacy rate of over 90%)
40 credits
Partial Instructions
20 credits
Well done!
The availability, supply and treatment of water is different
around the world but by using our knowledge and skills
we can ensure this vital resource is made available to all.
‘Everyone has the right to access the technologies
that are essential to life.’
What can you do?
Reduce water
Turn off the tap while
brushing your teeth
Take showers
instead of baths
Use only what you need
when making a cup of tea...
Wash fruits and vegetables
in a bowl of water
What can others do?
Recycle water
Greywater is the waste water
from baths and showers. It can
be used to to flush toilets or
to water the garden
Sewage water (from toilets)
can be treated to remove
impurities and also used to
water the garden.
Thank you!