How to make a solar water distiller

Can you filter water without using a stove or fire? Well here’s an easy experiment which shows nature’s power to filter water using the solar energy. This is one for the Bear Grylls’s fans. When water gets heated to its boiling temperature it forms vapor leaving back all the suspended impurities.

We will boil the impure water but prevent the vapor from escaping and will condense it to get water free from grit.

Difficulty Level: Easy (Anyone can do it)

Time Required: 3 to 4 hours of bright sunlight

Resources Required:

1. Big pot (preferably of aluminium or black in color)

2. A smaller bowl (should fit inside the bigger bowl)

3. Transparent plastic wrap

4. A weight (maybe a small rock)

5. Duct tape or a rubber band

6. Sunlight

7. Water from any source


1. Fill the large bowl with the water you wish to distill.

2. Place the small bowl in the middle of the pot. Make sure that the level of water in the pot is less than the top level of the bowl. If you think the impure water might enter the bowl, you might want to suspend it somehow. Make sure the bowl doesn’t float or move its position.

3. Cover the pot with the transparent plastic wrap. Fix the wrap properly by using duct tape or by a rubber band.

4. Place the weight in the middle of the transparent wrap. The weight should be placed in such a way that the wrap forms a cone with the top of the cone just above the bowl so that the condensed water trickles into it.

5. Place the whole thing in bright sunlight and wait for some time. After about 3 or 4 hours you will find that clean water has trickled into the smaller bowl.

Frequently asked questions

Is the water completely free from impurities? Can I drink it?
This process will only remove the suspended impurities in water, like dirt, grass, pebbles, rocks etc. The water will evaporate and the vapor will be free from all the grit. But if the water contains some dissolved impurities then there is a good possibility that the vapor will too. This experiment should only be performed if you are sure that the water you are distilling is free from dissolved toxins.

I did this experiment with colored water. The water which remained in the small bowl is colored as well. Is it a wrong experiment?
Color pigments are very small in size. They enter the voids between two water molecules and stay there. Hence even when vapor is formed it is difficult to remove the pigment molecules. So there is a good chance that your water collected will be colored as well. This home made device is only for removing bigger impurities. As I have said in the previous answer it is important that you make sure that the water that you are filtering is free from harmful toxins.

Why should the pot be black or made of aluminium. Can I use some other pot? Aluminium is a very good absorber of heat. The color black too is the best absorber of heat. So, to speed up the heating process of water you can use a black pot made from aluminium.

I did this experiment with dirty sea water. Though the distilled water looked clean to me, it still tasted salty. Is it possible to remove the salt?

Yes, boiling will remove salt to a certain extent. When the water turns to vapor, the salt is left behind. You might have done something wrong with your experiment. The impure water from the pot must not come in contact with the water in the bowl.

Quick tips

1. A black pot made from aluminium speeds up the process

2. A transparent wrap will allow more sunlight to pass through which will help heat the water at a faster speed.

Things to watch out for

1. Remember this is just a crude way to filter water. If the water contains toxins or pathogens simple distillation is not enough.

2. Make sure the impure water from the pot does not enter the smaller bowl, otherwise you will have to redo the experiment from scratch.

3. Clean the pot after use, as all the contaminants from the water will now be concentrated in it.