Final answer:
In environments lacking functional plumbing and clean drinking water, waterborne diseases such as typhoid, cholera and diarrhea, caused by pathogens in contaminated water, are likely to spread, leading to significant public health issues.
Step-by-step explanation:
The disease that would be potentially propagated in an environment without functional plumbing and in which drinking water is contaminated with sewage is a waterborne disease. These diseases are caused by pathogens such as protozoa, viruses, bacteria, and intestinal parasites present in feces that can pollute groundwater sources, a primary source of drinking water.
Poor sanitation measures can significantly increase the risk of these diseases, which include typhoid, cholera, and various forms of diarrhea. According to the World Health Organization, a majority of diarrheal disease cases, which result in millions of deaths annually, are attributed to unsafe water supplies. Furthermore, the lack of access to clean water and functional sanitation services puts billions of people at risk, often resulting in detrimental health outcomes, particularly for children under the age of five.