Texas Wastewater Class B Practice Exam

The correct answer highlights that potable drinking water is a key contributor to the dissolved oxygen content in raw sewage. When drinking water enters the sewage system, it typically retains some level of dissolved oxygen. This oxygen is crucial for the microorganisms that will later break down waste in the treatment process.

In contrast, other sources such as industrial waste often contain organic materials or chemicals that do not contribute positively to the oxygen levels necessary for effective biological treatment. Stormwater can dilute sewage concentrations but does not significantly increase dissolved oxygen. Agricultural runoff may introduce nutrients into the water, but it typically does not enhance the oxygen content in a beneficial manner for sewage treatment.

Understanding the role of drinking water in sewage systems underscores its importance in maintaining adequate levels of dissolved oxygen for the biological treatment processes essential for effective wastewater management.