Water for Everyone: S3 - the Solar Still Solution

STEM Challenge 2014

We are Megan, Astrid, Freddie, and Nicholas

We are all musicians in Year 8 at Wells Cathedral School in Somerset

Water is for life and for people:

Everyone needs clean water to live a healthy life.We often take clean water for granted in the UK.Many people in other countries don’t have clean water to drink.

Did you know that five children will have died from diarrhoea caused by drinking dirty water by the time we finish speaking?

A Solar Still uses distillation to separate clean water from dirty water.

Solar energy heats the water so that it evaporates to release clean water vapour.

The warm vapour rises and condenses on a cool surface to form clean water droplets.

We decided to make a Solar Still

How does it work?

EvaporationSolar radiation warms

the water up. As it warms up, the

water turns into water vapour.

CondensationWater vapour

condenses on a cold surface.

Clean water droplets can be collected to drink.

DistillationDistillation apparatus

separates clean water from a mixture by evaporation.

Then it collects the water by condensation.

We developed the Solar Still Solution (S3) which can produce clean drinking water for anyone, anywhere in the world.

It is made from cheap, locally available items, and is lightweight and easy to carry around.

It uses solar energy and can safely separate clean drinking water from saltwater and dirty water.

Our solution was the S3 Solar Still

We made the S3 Still using recycled items from our parents’ kitchens!

• An old metal measuring cup to hold the dirty water.• A metal jam sieve without its handle, for the water to drip through.• A sterilised white plastic tub to collect the water and keep it cool.• A clear plastic sandwich bag to let the sunshine in and allow condensation.• Some fine metal wire to make a dome frame to hold the bag open.• Two old elastic bands to hold the dome in place and seal the Still.

We tested the still to see if it could separate freshwater from saltwater

• Silver nitrate was added to water collected in the S3 tub.

• We did three replicates and all three stayed clear.• We had made

freshwater!

• If salt was present, the water would turn cloudy.

We tested the S3 Still to see if it could make clean water that was free from microbes

• We made some agar plates.• We sterilised some needles in a hot flame.• We used them to put water from the tub on the agar.• We had a control plate with no water on it.• We also had a dirty water plate to make sure microbes would grow.• We incubated the plates for 24 hours in a warm place.

We found no microbe growth on our Agar plates for the Still samples.There was no growth on the control plate either.There was lots of microbe growth on the dirty water sample plate.The test had worked. Our S3 Still could produce clean drinking water as long as we kept it clean.

The S3 Still produced clean drinking water!

1 2 3

The S3 Still was cheap to make, free to run, lightweight and portable.

It easily produced freshwater from saltwater.

Our tests showed that as long as the equipment was sterile, it could produce freshwater that was free from microbes.

We really enjoyed doing this project. Thank you!

Our project found a solution to provide Water for Everyone!