Water starts in storage reservoirs so there is a supply for treatment. It comes from rainfall, runoff and piping. Mesh screens filter out larger particles in the flow (like branches) and add some aeration. At this point, adding coagulation chemicals to the flow helps the smaller particles clump to create the flocculant. This requires mixing. The newly created floc heads through the clarifier where the heavier particles drop to form sludge (sedimentation). The sludge is farmed and carefully disposed of. Now that the large and medium particles have been removed from the water it’s time to work on the small ones. The clear water now heads through a series of filtration techniques, ranging from sand filters, ozone injection, and activated carbon. Once the water is filtered, it still needs disinfection treatment for microscopic bacteria. Typically chlorine is added for the disinfection. Finally, the pH is adjusted to make the water suitable for drinking (and non-corrosive to the piping).
Here’s a video that shows that process:
Of course, Fluid Technology can provide the equipment for aeration, mixing and filtration.