By Ed Lavandera and John Sutter, CNN

(CNN) -- A tall chain link fence, shrouded in vines, surrounds an aging water well tucked away in this small town just west of San Juan. A metal sign carries a warning in Spanish to anyone who approaches: "Danger. Do Not Enter."

That doesn't stop Juan Carlos Oquendo, 39, from peeling away a corner of the fence and jumping inside. He's brought a van load of containers to fill.

But what he doesn't fully understand is that water from the faucet is potentially contaminated with industrial chemicals that can cause serious health issues.

"I'm going to drink it. I've drank it before. It tastes fine," Oquendo told CNN as he filled his jugs. "If I don't drink water I'm going to die. So I might as well drink this water."

Oquendo stresses that he's willing to take this chance because access to clean water in his neighborhood has been extremely difficult for much of the last month since Hurricane Maria wiped out the water system on the island.

Just before CNN spotted Oquendo at the water well site, a team of scientists from the US Environmental Protection Agency was collecting water samples from the well.

The EPA is focused on this site because the well sits on what's called the Dorado Groundwater Contamination Site, which was listed in 2016 as a Superfund site in Puerto Rico. The area is polluted with industrial chemicals, including tetrachloroethylene and trichloroethylene, "can have serious health impacts including damage to the liver and increasing the risk of cancer," the EPA said when it designated the site as contaminated.

Gary Lipson, the EPA Incident Commander working in Puerto Rico in the aftermath of Hurricane Maria, says nearby residents have been drinking potentially contaminated water from this well.

"It's a concern both in public health and perception. We understand that people are hurting right now. We understand there are a lot of thirsty people out there, and they are accessing whatever water they can," Lipson told CNN. "We are trying to ascertain if it poses any hazards or not."

The EPA has "provided information to the Dorado community emphasizing that they must avoid using wells on the western portion of the site," the agency said in a statement Sunday.

That is the same area where CNN saw Oquendo tapping into a well.

EPA teams gathered water samples this weekend from at least six wells inside the Dorado Superfund site. A series of tests will determine the contamination levels.

EPA officials say the results could be made public by the end of the week.

One well on the Dorado Groundwater Contamination Site has been approved by the Puerto Rican water authority and federal officials for public use. Thousands of residents wait in a shopping center parking lot to fill up containers of water.

Puerto Rico Gov. Ricardo Rossello also says the territory's Department of Health has tested this water and deemed it safe.

"What people need to know is they did pass the Clean Water Act and standard," Gov. Rossello told CNN. "If it's non-drinking water, we're not going to be serving it. But if it complies with the Clean Water Act, it is going to happen."

CNN reviewed documents published in 2016 as part of the EPA's move to designate the Dorado Groundwater Contamination Site as a Superfund location.

It's unclear exactly which parts of the area may be contaminated.

"The EPA is in the process of examining the precise extent and location of this contaminated groundwater plume," said the agency's news release on Sunday. "Data gathered by EPA in 2015 showed that some wells in the western part of the area are contaminated, while some wells in the eastern portion of the area meet drinking water standards. The entire area, including many wells regardless of contamination levels, was included in the designated Superfund site boundaries as a precautionary measure because groundwater contamination can move over time and EPA wants to study the entire area."

David Carpenter, Director for the Institute of Health and the Environment at the University of Albany, said "it is reasonable to distribute this water under the present circumstances" but there are no safe levels for carcinogens in water.

"It is certainly likely that these wells will have contamination," Carpenter said after reviewing EPA documents.

The documents show that three different wells contain concentrations of toxic chemicals known as PCE and TCE that exceed the agency's maximum contaminant levels for drinking water, said Erik Olson, the Health Program Director with the Natural Resources Defense Council in Washington, DC.

Olson also says the documents show the Superfund site contains karst limestone, "which is notorious for allowing contamination to spread easily and quickly."

"It is irresponsible to not make every effort humanly possible to find and provide safe drinking water as soon as possible," Olson wrote to CNN in an email.

Juan Carlos Oquendo returned to his home in Dorado and unloaded the bottles he filled at the well. The home he shares with his siblings and mother was severely damaged in the hurricane.

The roof was ripped off the second floor, and the family is still living without electricity and running water.

Oquendo's mother, Carmen Rojas, recounted the moment when the house started coming apart in the storm. Since then, she says, emergency officials have delivered only two small packages of water to residents in her neighborhood.

Rojas, 68, says she started drinking the Dorado Superfund well water about two weeks ago and immediately started feeling stomach pains.

"I don't know what's causing it," she says, "but it might be because of the water."