This activity has been provided by STEAMfest sponsor MEL Science!”
Step-by-step instructions
Cut the bottom off the plastic bottle. Unscrew the lid of the bottle, make a hole in it with the awl and place cotton wool in the lid. Close the bottle and turn it upside down. Place layers of sand and charcoal in the bottle. The more layers, the better the purification will be. The filter is ready!
Process description
Dirty water contains many organic and mineral impurities, and also various insoluble particles of dust and earth. The sand purifies the water of insoluble particles. Charcoal has good adsorption and so adsorbs organic and mineral impurities. However, this filter has a considerable drawback: it does not purify the water from bacteria and heavy metals. So after filtration the water should be boiled well.