The vehicle that officials say was used to pilfer water from a Ventura County water district’s fire hydrant was a white water tender truck, not a red Ferrari driven by a mustachioed man in a Detroit Tigers baseball cap and a Hawaiian shirt.

But in a complaint filed by the Calleguas Municipal Water District, the utility points the finger at “Magnum, P.I.” star Tom Selleck — and they say they hired a real P.I. to prove it.

As California’s historic drought worsened, water from a public hydrant was delivered to Selleck’s sprawling Hidden Valley ranch, according to court documents filed against the veteran actor.

On multiple occasions between 2013 and 2015, a white truck filled up at a Thousand Oaks hydrant and hauled water to Selleck’s 60-acre property, according to the complaint. To document its case, the water district spent nearly $22,000 to hire the real private investigator.

Calleguas says the “Blue Bloods” star and his wife, Jillie, who is also named in the complaint, are barred from using water from the hydrant because their property is located in a different water district, Hidden Valley Municipal Water District.

“Our 630,000 customers are ripping out their lawns, drastically cutting back on the water they use,” said Eric Bergh, resources manager for the Calleguas Municipal Water District. “The water that we have secured for them, that they have paid for, should remain in district boundaries.”

Representatives for Selleck have not responded to several requests for comment. The Ventura County Sheriff’s Department reviewed the allegations and was unable to establish that a crime had occurred, according to a department spokesman.

Before filing the complaint, the water district tried to get Selleck to stop taking water from the hydrant. In November 2013, Calleguas sent cease-and-desist letters to both Selleck’s home and an Avenue of the Stars address linked to the property, according to court papers.

As recently as March, the water truck was spotted on four days filling up at the same hydrant and delivering water to Selleck’s estate, according to the complaint.

The incident highlights the fragile water supply at the enclave of Hidden Valley, whose 37 ranches are owned by celebrities and business elite. Selleck, son of the late San Fernando Valley real estate magnate Robert D. Selleck, has lived there for nearly three decades.

Hidden Valley properties are not connected to the public water supply, and the Hidden Valley Municipal Water District does not actually provide drinking water. Instead, residents rely on about 100 wells to supply their needs, according to county records.

Some wells dry up during a drought, forcing residents to look elsewhere, Bergh said. Another Hidden Valley resident also received a cease-and-desist letter and apologized to Calleguas, Bergh said.

In 2009, when the state was mired in its final year of a previous drought, Selleck and about five others gained permission to fill up trucks from a water hydrant in nearby Lake Sherwood, said Reddy Pakala, then the director of water and sanitation for the Ventura County Public Works Agency.

That special agreement lasted a few months. Pakala said it was canceled after he learned about a law that bans transferring potable water outside a district’s boundaries.

To those living near the Thousand Oaks fire hydrant named in the complaint against Selleck, the sight of a truck filling up with water was common.

“It’s always the same guy and truck,” said Rick Kaiser, who lives down the street from the hydrant.

Anna Guzman, who has a clear view of the hydrant from her front yard, said a truck typically arrived about 6 a.m. Her daughter, Alejandra Yela, who lives with her mother, wondered why officials didn’t step in sooner if water was being drawn surreptitiously.

“We’re in a drought,” Yela said, “and everyone’s trying to save water.”