Standing at the Capitol before a row of doctors wearing white lab coats and Democratic lawmakers, Ruiz read the names of seven minors who have died while in immigration custody or shortly after release since last December.
He said the first reported death of a 7-year-old Guatemalan girl, Jakelin Caal Maquin, prompted him to visit CBP facilities.
"The conditions I saw were deplorable, subhuman and heartbreaking," said Ruiz, who has experience as an emergency room doctor. "Open toilets in crowded cells without any privacy. Visibly sick children coughing on one another. Babies who were dirty and didn't have diapers."
A CBP spokesman said agency policy prohibits him from commenting on pending legislation.
While agency guidelines do not require health screenings by medical professionals for every detainee, they say medical care, clean drinking water and edible food should be available to migrants.
In January, in response to a surge of children and families being apprehended at the border, then-CBP Commissioner Kevin McAleenan directed the agency to beef up medical efforts, including health assessments for minors, to better care for people in custody.
McAleenan, now Department of Homeland Security acting director, testified before the Senate Judiciary Committee this week that 200 medical professionals are providing screenings at the border.
Still, Democratic lawmakers supporting Ruiz's bill say CBP officers are woefully underequipped and underresourced to meet the basic needs of detainees, many of them Central Americans who say they are fleeing extreme poverty and violence in their home countries.
"I hope that the House of Representatives and also the Senate will send a strong message that the United States, the strongest and most prosperous nation on earth, is one that will treat humanely those folks who come here seeking refuge," said Democratic Texas Rep. Joaquin Castro, chairman of the Congressional Hispanic Caucus.
This comes as the White House is asking Congress for $4.5 billion to respond to what it calls a "humanitarian and security crisis at the border."
Ruiz said that Congress shouldn't hand out that money without improving conditions for CBP detainees, as outlined in his bill.
"This is the blueprint of where that humanitarian aid can be spent," he said.