Puerto Rico's drinking water may be the most contaminated in the U.S., a top Republican suggested at a House Energy and Commerce Committee hearing Tuesday morning where contaminated well water in the wake of Hurricane Maria was a major topic.

"In Puerto Rico, Hurricanes Irma and Maria uncovered the intensified issues associated with aging and inefficient energy infrastructure, contaminated sites that are rapidly multiplying, landfills that are already overflowing, and possibly the most contaminated drinking water supply in the United States,” said Rep. John Shimkus, R-Ill., the chairman of the committee’s environment panel, who led Tuesday's hearing on environmental effects from the storms.

"Residents across the island are still without power and a reliable source of drinking water," he said. "Many are drinking potentially contaminated water because water purification systems have largely failed because of the storm."

He noted that citizens in the municipality of Dorado have been forced to drink well water at a toxic Superfund clean-up site overseen by the Environmental Protection Agency. The agency has warned citizens not to, but the lack of fresh water on the island has driven residents to take the risk.

After the fact, the EPA determined that the well water met minimum safe drinking water standards.

The House hearing was part of a series the energy committee is holding to examine the hurricane response effort, while looking at what Congress can do to help Puerto Rico and the states hit by this year’s devastating storms. Shimkus said the hearing would inform possible legislation required to respond to environmental concerns in the aftermath of the storms.

Shimkus raised the drinking water concerns in opening the hearing, which featured a number of EPA regional office chiefs who have overseen the environmental response on hurricane-ravaged states and territories.

Rep. Paul Tonko of New York, the top Democrat on the environment panel, also raised the drinking water issue, saying it is "simply unacceptable."

Tonko said he is particularly concerned about the state of disrepair that much of the U.S.'s water systems are in. He sees the lacking infrastructure as one of the reasons that Puerto Ricans were forced to seek out water at toxic waste sites.

He said the water at the site was later tested to be safe, but there have been other cases of contamination in rivers used by residents for bathing and drinking after the storm, which has led to the spread of bacteria and disease.

The EPA issued an update Tuesday that detailed a new effort to divert potentially toxic forms of waste from being tossed into landfills on the island to curb contamination of waterways and groundwater supplies.

Later Tuesday, the House Natural Resources Committee will hold a separate oversight hearing on Puerto Rico and the U.S. Virgin Islands.

Ahead of the hearing, Rep. Raul Grijalva of Arizona, the top Democrat on the committee, blamed the lack of adequate response in the U.S. territories on his Republican colleagues.

“Puerto Rico and the U.S. Virgin Islands are in the midst of a humanitarian and financial crisis, but committee Republicans won’t talk about that,” Grijalva said. “Instead they’ll talk about their desire for the federal government to take over spending in the Virgin Islands, the efforts of Puerto Rico’s oversight board to expand its own powers, or a pseudo-investigation into the Whitefish contract even though the real work is being done by the Department of Homeland Security Inspector General."

He said the Congress will talk about everything "except for the fact that for the past two months American citizens have been living in the dark and are struggling to survive without clean drinking water or a sustainable food supply."

Grijalva said that in cities such as Houston or Miami the same situation would have not been allowed to persist. "It is well past time that the federal emergency response matches those provided to areas on the U.S. mainland.”