When we pour water down on the sink, where does the water go?

Depends on where you live.

In most places, wastewater has historically been treated to remove potential pollutants, then sent down the river.

In recent years, places where fresh water supplies are limited, but where the city can afford the additional processing, wastewater is treated and reused for non-potable purposes.  In Orlando, Florida for example, recycled wastewater is used for irrigation on municipal roadside and median landscaping.

it sends the water to seperation plants to get the humans refuse out of it , the its filtered before going to the sea of for recyling into grey water for gardening , actually cleaned water is drinkable because it been filtered .

Are you actually serious on this enough to ask? No offense, but pick up a book or go outside and play or something, no more video games, place that effort in learning something that will benefit many if you put it to proper use

the detention pond

water is never wasted where ever it goes.

its kinda impossible. its not man made.

That depends. My house has a separate grey-water system, so the water goes through the soil to my pond. Most houses have a single system, sending the water to a septic tank and then to the soil or through a sewage main to the wastewater treatment plant and, after treatment, to the nearest body of water. A few use the effluent for irrigation of forests or grassland.

In the sewage. The soil absorbs it or it goes back to open water.

it gets saved because all water is holy water blessed upon us by god.

I'm hoping that not stirring up the waters of that nature you don't want people to get so worked up that the people doing a good job feel appreciated..

That depends on your city’s wastewater setup. Smaller cities just pump all the water from the drains into a sewage lagoon outside of town where the water runs through several stabilization ponds that filter the water naturally and it is left to just evaporate. Larger cities will run the wastewater through a treatment plant and put the treated water back into the water supply. 

It goes back to be filtered and purified I think