The steps involved in getting clarified water from wastewater are as follows:

The Physical process:

i. Wastewater is passed through bar screens to remove large objects like rags, sticks, cans, plastic, packets, and napkins.

ii. Water then goes to a grit and sand removal tank where sand grit and pebbles settle down.

The Biological process:

i. The water is placed in a large tank where solid impurities, like feces, settle down and are removed with a scraper which is called sludge. Floatable solids like oils and grease are removed with a skimmer. Water, thus cleared, is called clarified water. The sludge is transferred to a separate tank where it is decomposed by the anaerobic bacteria.

ii. Air is pumped into the clarified water to help aerobic bacteria to grow. Bacteria consume human waste, food waste, soaps and other unwanted matter still remaining in clarified water.

After several hours, the suspended microbes settle at the bottom of the tank as activated sludge. The water is then removed from the top.

The Chemical process:

Then any disinfectant such as chlorine tablet is added to the filtrate. Now, the wastewater is fit for drinking.