Final answer:
The Indus Valley Civilization was the first civilization to have sewer systems in their cities, including advanced drainage systems and indoor toilets connected to these networks.
Step-by-step explanation:
The first civilization to have sewer systems in their cities was the Indus Valley Civilization. Excavations at ancient Indus Valley sites in present-day Afghanistan, Pakistan, and India have revealed advanced citywide drainage systems with covers for servicing and indoor toilets that were connected to this network. These systems were designed to efficiently remove water and waste from the cities, similar to modern underground sewer systems.