A drug-dealing Long Island couple was caught with enough fentanyl to kill more than 42,000 people — in an operation so sprawling, it’s “almost incomprehensible,” authorities said Monday.

Caleb Moran and Jessica Medina-Rivas, both 28, of Holbrook were charged with 56 combined counts of the highest narcotics offenses in the state after one of the largest drug busts in Suffolk County history, officials said

“This wasn’t just a drug bust. It was a ticking time bomb sitting in the middle of a quiet neighborhood,” Suffolk DA Ray Tierney said — as the suspects were arraigned and held on $2 million bail apiece.

Cops found 14 kilos of cocaine, 12 kilos of meth, thousands of pills, 3 ounces of fentanyl, black tar heroin and 20 pounds of cannabis among the stash in the pair’s home during a raid Aug. 22, Suffolk prosecutors revealed during the pair’s court hearing.

Authorities also recovered two unregistered guns in the home, a pair of bulletproof vests, blenders, digital scales, a pill press, packaging equipment, more than $118,000 in cash — and “dragon’s breath” shotgun shells that shoot out sparks, officials said.

The sprawling ring unraveled after the pair sold more than 2 ounces of coke at a time and various amounts of fentanyl to an undercover detective on five occasions over the summer, prosecutors said. 

During one deal, Moran allegedly handed over fentanyl and warned the officer not to sell it “pure,” admitting the potent batch had already led to overdoses — including a fatal one.

The suspect recommended that his “buyer’’ use soap shavings to cut the lethal drug and stretch his product, authorities said.

“Two million dollars in product — among the largest seizures in Suffolk history,” county Police Commissioner Kevin Catalina told reporters.

“The scale of this alleged operation is almost incomprehensible,” he said.

Investigators found about 80 pounds of cannabis that same day at a Patchogue motor sports business operated by Moran’s father, too, prosecutors said. 

While the elder Moran was not charged, subsequent UPS shipments of weed from California to the shop were intercepted by police. 

Lawyer Raymond Perini, who represents Caleb Moran, told The Post that his client’s father has fully cooperated with police and is not suspected of any wrongdoing. 

Tierney made clear that the investigation is still active and that more charges could be on the horizon depending on what authorities find. 

Moran and Medina-Rivas both pleaded not guilty to operating as a major trafficker, the state’s top narcotics charge, and dozens of possession and sales counts.

Each was held on $2 million bail or $8 million bond and faces 15 years to life if convicted. 

Medina-Rivas is set to appear Oct. 27 while Moran is due back in court a day later.