San Francisco is a pretty dirty city. One interesting aspect to the city's garbage life is the ecosystem/economy that's developed around collecting recyclable waste. While there's essentially no public recycling bins, homeless and others will collect all CRV-recyclable materials from nearly every trash can in the city. It's not unusual to be woken up in the middle of the night to the sound of your trash can being knocked over by somebody looking to score some plastics and glass.

Oh, there's still plenty of room left in there.

Trash collection is provided by Norcal Waste Systems, which operates Golden Gate Disposal, Sunset Scavenger in San Francisco, as well as subsidiary companies across the country.

Not everything is appropriate to toss in the trash — some things, like hypodermic needles and batteries, are unsafe and should be discarded through other means. Many items are recyclable, and food scraps and yard trimmings could do a whole lot of good if put elsewhere, like the city's huge compost heap. Norcal Waste Systems provides customers with three wheeled bins: black for trash, blue for recyclables and green for organic materials. In an effort to promote recycling and composting, the company operates on a price structure that rewards customers who regularly toss 20 gallons or less by discounting their $23.58 weekly garbage collection fee by 23%. The other two carts are picked up free of charge.

Residents can also reduce the volume of their trash by switching to reusable versions of the things they're throwing out, such as containers, flatware and even sanitary napkins. Where possible, people should try to stack trash items within each other, such as bulky food containers, to prevent large pockets of air from taking up precious landfill space.