When teaching children about water purification, a good learning tool can be simple activities that let them see theory in action. Aside from water purification methods that involve dangerous chemicals or advanced equipment, many filtration methods can easily be replicated and conducted by children. Common filtration techniques include sand, coffee filter and cheesecloth. Children can also complete simple chemical purification methods under attentive adult supervision.
Purification Using Sand
A great way of showing children how water purification works in nature is to create a model of an aquifer using porous rocks (such as pumice stones) and sand. Set a perforated piece of plastic or metal on top of a jar. Place an aluminium can with the lid and bottom removed on top of the barrier. Create a layer of tightly packed rocks at the bottom and layer wet sand on top of the rocks. Slowly pour cloudy water through the layers and watch the clear water collect in the jar.
Purification Using a Filter
A simple activity that easily illustrates the basic concept of water purification can be done with household items. Have children slowly pour a small amount of cloudy or particulate water though a coffee filter or piece of cheesecloth into a coffee can or wide-mouth jar. If the water is still cloudy, pour it through a new coffee filter. The children should be able to see a ring of particles or dirt on the filters.
Purification Using Chemicals
Under close adult supervision, children can purify water using basic household chemicals. Liquid iodine (2%) can be used to purify water. Children should add five drops per quart of clear water. Chlorine will also purify water. Both iodine and chlorine come in safe-to-handle tablets that can easily fit in water bottles. If your water purification activity is ultimately intended to create drinkable water, children should use both a filter and chemicals to purify water before drinking.
Purification by Boiling
Purifying water by boiling avoids chemicals and ensures that the water is sufficiently purified. Children should be properly supervised at all times when near boiling water. In order to kill all the bacteria or microorganisms in the water, be sure to raise the water temperature to 82.2 degrees Celsius and keep it at a steady boil for at least one minute. To illustrate that all microorganisms have been killed via boiling, show children a sample of water before and after boiling under a microscope.