How we tested
A carbon filter on the lid keeps the smells in but still allows oxygen to enter so decomposition can occur, cutting down on trips to the compost heap. These small buckets fit in a cabinet beneath the sink, and some are attractive enough to keep on the counter. We had test cooks use three kinds of compost buckets (lined with biodegradable bags) over several weeks, recording how easy they were to fill and empty, and if they let out any odors, as well as how often they needed to empty the bucket or toss the liner (we measured this by the number of recipes a cook could complete before having to empty the bucket).
All were easy to empty, all had carbon filters, and each passed daily sniff tests with flying colors. Then one day the lid popped off a bucket that had gotten knocked off the counter, and the stench cleared the kitchen. The virtue of our winner was suddenly clear: Its latching lid won’t pop open even when banged about.