The City maintains nearly 400 miles of sewer mains and transmission lines throughout the City, allowing the sewage to make its way from the consumer to the wastewater treatment plant where it can be properly cleaned and treated.
In the primary stage, solids are allowed to settle and removed from wastewater.
The secondary stage uses biological processes to further purify wastewater.
To complete secondary treatment, effluent from the sedimentation tank is usually disinfected with chlorine before being discharged into receiving waters. Chlorine is fed into the water to kill pathogenic bacteria and reduce odor. Done properly, chlorination will kill more than 99 percent of the harmful bacteria in the effluent.
Many states now require the removal of excess chlorine before discharge to surface waters by a process called dechlorination. This protects fish and other aquatic life as the cleaned water returns back to the environment.