Officials in Paradise are trying to understand how much of the city’s water supply has been contaminated with a carcinogenic chemical as a result of last November’s deadly Camp Fire.

The Paradise Irrigation District announced earlier this month that tests had come back positive for benzene — a flammable chemical used in the production of gasoline and plastic — but the extent of the contamination is still unclear.

Samples collected at some residential water meters didn’t contain any benzene. Other samples did, and one revealed benzene levels about 15 times the state limit for drinking water. According to the Center for Disease Control and Prevention, long-term exposure to benzene can cause anemia or cancer.

The November fire burned down close to 14,000 homes and effectively melted some of the plastic piping in Paradise’s water system, releasing benzene into the water supply, according to Reese Crenshaw, an engineer with the state Division of Drinking Water.

According to Crenshaw and other state officials, this is only the second time that they know of that this has happened. The first was in Santa Rosa, where officials discovered benzene contamination after the devastating Tubbs Fire in 2017.

Ben Horenstein, Santa Rosa’s former water director, said he’d never considered what a wildfire could do to the plastic in their water system. Then he received a complaint from a resident who told him the water smelled and tasted like petroleum.

“I have to believe this has occurred elsewhere, and it was unbeknownst to the water agency or the residents,” Horenstein said.

It took Santa Rosa the better part of last year to identify the extent of their benzene problem and to replace the damaged piping. Horenstein and other local officials initially expected the project to cost around $47 million, but it only ended up costing $5 to $6 million. The contamination of the system was limited, and flushing the pipes proved very effective, he said.

Officials in Paradise are still trying to map the extent of the damage to its water system and what it means for people who just want to return home. Mickey Rich, a spokeswoman with the Paradise Immigration District, said the community is working closely with the Division of Drinking Water and other agencies so their case can be a model to others.

“In the end, we’re going to have safe water again,” Rich said.

Horenstein said the benzene problems in Santa Rosa led to proactive testing in Paradise and the development of a testing protocol that could help other communities hit by fires in the future.

Running water is being restored in Paradise, but the Paradise Irrigation District has advised residents against drinking, bathing or brushing their teeth with the tap water until they have more information.

Paradise’s drinking water isn’t the only water the Camp Fire contaminated. Several area streams show elevated levels of aluminum, iron and antimony. The metals may be residue from the homes and cars the Camp Fire burned, which were then washed into local streams by winter rains.

Officials are still analyzing the area’s watershed contamination.

KCHO reporter Marc Albert contributed to this story.