Harding School took a big step toward sustainability Friday, unveiling its zero-waste cafeteria, the first school in Santa Barbara County — and one of the first in the nation — to do so.

“We’re not teaching students something they may or may not retain,” principal Sally Kingston said at the morning’s ceremonies, attended by school and city officials at the Westside campus, 1625 Robbins St.

The students, she said, will have years of hands-on experience sorting, recycling and composting their waste — a habit they’ll carry with them as they get older.

The zero-waste program is an effort at diverting as much trash as possible from the local landfill by either recycling or composting as much waste from the cafeteria as possible. Kids learn to put all food scraps in the yellow composting bins and recyclables in the blue bins.

In this program, the smallest details matter. Milk and juice cartons out of the cafeteria come unglazed for easier composting. Even the cafeteria’s plates, bowls and utensils — once a huge part of the school’s trash — are put in the composting bin. They’re made of corn.

“This is … good,” said Santa Barbara schools Superintendent Brian Sarvis, chewing on a bite of the technically edible plate. The homemade pizza and salad greens the plate held tasted much better, he said.

The zero-waste cafeteria is an approach to sustainability that treats food waste as energy, not as trash.

“We’re educating people that food is not waste,” said Eric Lohela, recycling coordinator for the city of Santa Barbara, which, along with waste hauler Allied Waste (formerly known as Browning-Ferris Industries) partnered with Harding School to roll out this program.

As a result, about three 65-gallon bins are filled with compostable material each school day, from the cafeteria as well as classrooms. The lot is hauled off on a regular basis to the Engel & Gray Inc. compost facility in Santa Maria, where the waste is broken down into soil amendment.

Harding’s zero-waste cafeteria runs in conjunction with the school’s in-house nutrition program, which began in August after the school decided to opt out of the district nutrition program. Around $40,000 in donations and grants established an independent cafeteria, according to Kingston, who hopes to sustain funding through more grants as well as reimbursement for meals.

It was a choice that gave Kingston extra work with regards to the school’s food offerings, but the personal responsibility also allows the school to make its own choices about the food that winds up in the students’ bellies, and in the waste bins.

“They’re eating better every day,” she said, adding that the school’s in-house program emphasizes whole foods that are locally available.

The zero-waste endeavor has only been running for a month but already the kids are pros.

“I put my yogurt cups in the recycle bin,” said Diego, 6. His friend and classmate, Asher, meanwhile, explains the process by which plastics and other materials get recycled.

“They melt them down into little pellets,” he said.

While their seatmate, Aidan, has had some training in recycling at home, their other friend, Juan Pablo (J.P. for short), just began learning the basics of waste diversion at Harding.

Harding School won’t be the only school with a sustainability program for long. Peabody is not far behind, with an emerging environmental program of its own.

“This is fabulous,” said Santa Barbara City Councilwoman Helene Schneider.

Santa Barbara has a waste diversion goal of 70 percent, and in 12 more years, an ambitious 85 percent. With time and luck, said Schneider, the kids will learn to recycle and compost like it’s second nature.

“They might even teach their parents,” she said.