What does the term 'sewage' refer to?

The term 'sewage' refers to all household wastes, which encompasses both human excreta and a variety of other materials that are typically flushed down the drain. This includes water from sinks, showers, and toilets, as well as waste from households such as food scraps and hygiene products. Understanding this broad definition is crucial, especially in septic system installation and maintenance, as it emphasizes the need to manage different components of wastewater effectively to prevent environmental contamination and ensure the proper functioning of septic systems.

In contrast, the other options are limited in scope. The first option focuses solely on human excreta, which is only a part of what sewage entails. The second option incorrectly identifies irrigation water, which is not considered sewage since it is not waste material. The last option, concerning industrial wastewater, pertains to a different category of waste that may require distinct treatment methods and is not included in the residential definition of sewage. Thus, the correct answer encompasses the full range of household waste, highlighting its complexity and the importance of proper septic system design and function.