The water that is used and goes down the drain is then taken from our homes through pipes which form a collection system of wastewater from different neighborhoods. It eventually leads to a wastewater treatment plant which treats and cleans it and then it is put back into the environment. There is also a drinking water distribution center which then distributes it through the pipes into homes. This entire system is safe because all large unwanted particles are separated and then healthy bacteria is added. Lastly all other particles are are filtered out and it is sanitized with chlorine.