Throughout the United States, sewage treatment plants collect billions of gallons of wastewater. First collected in sewers, wastewater then makes its way to the plant for treatment before it is released again into the environment. It is hoped that, as a
result of this process, the waste will have no adverse effects either on the environment or on humans. However, the actual practices of the waste-purification process can be health hazardous.In the U.S., it is mandatory that all waste is properly treated before release.
However, errors in the process can cause polluted waterways. This situation can make drinking, fishing, and recreation unsafe. The wastewater may also be discharged into the ground and used for irrigation. Either alternative could cause damage, including groundwater contamination, which could also be caused by leaks in underground fuel or chemical tanks at the treatment
facilities. The chemicals used in the waste purification process can also be harmful. Used in large quantities, these chemicals – including chlorine or chlorine dioxide gas -- can produce environmental risks. Storm water run-off might also pose a problem if contaminated with waste or other pollutants.
The often foul smell of sewage treatment plants can generally be attributed to hydrogen sulfide, which is toxic and can cause problems ranging from eye
irritation and nausea to toxic explosions. However, the odor is often diluted in the air and is usually of little or no harm.
Treatment plants can cause contaminated water. Potential contaminators are bacteria, nitrates, oxygen-depleting organics, and metals. Exposure can occur through drinking such water, direct skin contact, digesting fish from contaminated waters, or even swimming in such waters. Reactions can range from rashes to hepatitis.