It is a good introductory activity and can be adapted for all grades. Water in lakes, rivers, and swamps often contain impurities that make it look and smell bad. The water may also contain bacteria and other microbiological organisms that can cause disease.
Aeration is the addition of air to water.
It allows gases trapped in the water to escape and adds oxygen to the water. Filtration through a sand and pebble filter removes most of the impurities remaining in water after coagulation and sedimentation have taken place. In most municipal water treatment plants, disinfection is the last step before distributing the water. This activity demonstrates the first four water treatment processes. Have students describe the appearance and smell of the water.