In environmental engineering, the process of treating and cleaning waste water from homes and industries is commonly known as:

Introduction / Context:
This question is from environmental engineering and public health. It asks what we commonly call the process of treating dirty water from homes, offices, and industries before it is released back into rivers, lakes, or reused. Knowing the correct term helps when studying pollution control and civic infrastructure such as treatment plants and sewer systems.

Given Data / Assumptions:

• The focus is on the process that treats waste water from domestic and industrial sources.
• The options include waste water management, cleaning of water, sewage treatment, and decontamination.
• Basic knowledge of how cities handle sewage and waste water is assumed.

Concept / Approach:
Waste water coming from homes, offices, and many industries is commonly called sewage. It contains organic matter, suspended solids, pathogens, and sometimes chemicals. Before this water can be safely discharged or reused, it must pass through a series of treatment steps. These steps usually include screening, sedimentation, biological treatment, and sometimes advanced processes. The overall process is called sewage treatment or waste water treatment. Waste water management is a broader term that includes policy, planning, and overall handling of water resources, not just the treatment plant. Cleaning of water is too vague and non technical. Decontamination is a term more commonly used for removing hazardous agents in specific situations, not the routine treatment of all sewage in cities.

Step-by-Step Solution:

Verification / Alternative check:
Civics and environmental science textbooks describe sewage treatment plants or waste water treatment plants as key components of urban infrastructure. They often show flow diagrams labelled primary treatment, secondary treatment, and tertiary treatment, all under the heading of sewage treatment. Municipal corporations and engineering agencies use the same terminology in their plans and reports. This consistent usage confirms that sewage treatment or waste water treatment is the standard name for the process described in the question.

Why Other Options Are Wrong:

Waste water management as a general policy term is incorrect because management includes many activities beyond treatment, such as reuse, regulation, and conservation.

Simple cleaning of water without specific treatment steps is too vague and does not refer to the structured, multi stage process used in real treatment plants.

Decontamination used only for hazardous chemical spills is not the routine term for city wide treatment of domestic and industrial sewage.

Common Pitfalls:
Students sometimes pick broad sounding terms such as waste water management because they seem to cover more activities, but the question is specifically about the process of treatment. Others may think of decontamination from news reports about chemical accidents without realising that normal sewage contains many types of contaminants that require systematic treatment, not emergency procedures. Remember that in exam questions, sewage treatment and waste water treatment are the precise, commonly used terms for this process.

Final Answer:
The process of treating and cleaning waste water from homes and industries is commonly known as Sewage treatment or waste water treatment.