It's still up to a restaurant to decide to fill them, but the law provides detailed guidelines on how to do it safely.

A new law has passed in California this summer that offers a procedure to restaurants for refilling customers' reusable containers. The practice is becoming more common, as more and more diners strive to reduce single-use plastic with their takeout orders or leftovers.

Accepting reusable containers, however, has always been risky. It's hard to know where they've been, how well they were cleaned, and what cross-contamination could potentially happen if brought into a commercial kitchen. It has always been up to a restaurant to decide if they want to accept people's containers.

The new Assembly Bill No. 619 does not force restaurants to accept reusable containers – the practice remains optional – but it does clarify the guidelines for how to deal with them. From Nation's Restaurants News,