The Center for Investigative Reporting has been extensively covering the movement of people through the U.S.-Mexico border for years. They've put together a FAQ to explain what happens to children before they're put into the system, but after they've been detained by the Border Patrol.
From the story:
"Complaints to the U.S. Department of Homeland Security’s civil rights office describe poor conditions, including lack of medical care, insufficient food and water, and incidents of verbal and physical abuse. Because the holding cells are meant to be temporary, many do not have soap, showers or beds."
Read the full story at The Center for Investigative Reporting