Post Chlorination is the final stage of the purification process that is done before the water leaves the treatment plant. It mainly consists of the incorporation of minimum levels of chlorine into the product water down to diffusion. The exact reason for this step is to eradicate unwanted biological organisms (pathogens) by preserving a low level of chlorine in the piping network or plumbing system.
Is it very important to calculate the concentration of your chlorine throughout the post chlorination process and make sure their is consistency. Generally the precise amount of chlorine used for water treatment processes is determined by the quality of water that needs to be treated.