(CNN)Stephen Reifenstein never imagined he'd find himself relying on the services of a food bank.
He and his wife Kristina live with their two young children in Orange County, California -- one of the wealthiest areas in the nation. For nearly two decades, he worked in project control in the oil and energy sector. The job was comfortable, paying enough that the couple was recently able to purchase a home.
Then, as the story goes for so many people, the pandemic hit.
On April 3, Reifenstein found himself out of a job. The business that his wife had started a few months earlier was on hold. All the while, the mortgage payments, the car payments and the utility bills kept coming. The couple found themselves quickly blowing through their savings and decided they had to find a way to cut costs somewhere.
So Reifenstein signed up to volunteer at the Second Harvest Food Bank, and started taking some food home at the end of his shifts.
"You never really think things like this will be needed for you," he said.
Reifenstein and his family are among millions of people who find themselves turning to food banks during this time of uncertainty, as unemployment rates reach record highs, the prospect of more federal relief remains uncertain and the pandemic rages on.
That influx of new recipients, along with disruptions in the supply chain and increasing food prices, have put the nation's food banks under enormous strain.
"Food banks have been operating in this heightened disaster response mode since March," said Zuani Villarreal, director of communication for Feeding America. "The big question is: How long can we sustain this?"
Leaders at food banks are taking a number of measures in anticipation of the potentially challenging months ahead. But as the US battles a third wave of the pandemic, a critical line of defense against hunger hangs in the balance.
The percentage of people without access to adequate food has doubled
Lines at food banks across the country have gotten longer since March -- and many of the people in them haven't needed assistance before.
About 10.5% of US households were food insecure -- meaning that they had limited or uncertain access to adequate food -- at some point in 2019, according to a report published by the US Department of Agriculture last month.