Flocculation is a process that removes materials suspended in a fluid. A flocculant is added to a solution to join material particles together into flocs, which can then be separated from the solution as they will either sink as a sediment or float to the surface.

The flocculant we used was aluminum sulfate (alum), which was purchased at a pool supply store. A fan blade power by a DC motor mixed the alum and dirty water. The alum would attach to the large particles and sink them to the bottom of the tank, beneath the outlet.

After stage 1, the water passed through a steel wire mesh to catch any large particles that did not sink to the bottom. Next the water passed through several layers of coffee filters to catch the finer particles.

After the coffee filters in stage 2, the water passed through a layer of coarse sand, fine sand and activated carbon pellets; all these supplies were purchased from a pet supply store. A final coffee filter was added at the end to keep any carbon pellets from entering the clean water supply.