Well kiddo, the Indus Valley Civilization was a long time ago, around 2500 BCE. They were a big group of people who lived in the area of the Indus River, which is now in Pakistan and India. They had a lot of cool things, like big buildings, writing, and a system of sanitation!
Sanitation means keeping things clean and preventing sickness. The people who lived in the Indus Valley Civilization had a really impressive system for sanitation. They built special toilets in their homes that had a drain connected to a big sewer system. When people went to the toilet, their waste would go down the drain and into the sewer.
The sewer was really long and big, and it ran underground throughout the city. It was made of bricks and had manholes so people could clean it out. The waste water eventually flowed out to the river, where it was cleaned naturally by the water and the sun. This meant that the water in the river stayed clean, which was important for the people who lived nearby and used the river to drink, cook, and bathe.
The people who lived in the Indus Valley Civilization were also really good at keeping their streets and houses clean. They had a system of garbage collection, where people would throw their trash into a garbage bin that was collected regularly. They also had public baths, which were like big swimming pools where people could go to bathe and relax.
Overall, the people of the Indus Valley Civilization were really clever and innovative when it came to sanitation. They understood how important it was to keep things clean and prevent sickness. It's pretty amazing that they had such a well-designed system so long ago!