In the Shanghai 2010 World Expo's Urban Best Practices Area, one city is attracting much attention for its exhibit. Chengdu, Sichuan Province, has put a working "living water park" on display, helping to clean 15 tons of sewage from the Expo Park every day.

The natural water treatment system, which is based on Chengdu's own Living Water Park that it built in 1998, is an ecosystem that uses plants, such as reeds and duckweed, and stones to absorb pollution and harmful organisms from the water.

Besides demonstrating how the water treatment system works and how the clean water can be used, Chengdu's Expo exhibit displays what nature was like before being polluted by modern civilization and how it was damaged. Shaped like a fish, it takes into account Shanghai's climate and geography, as well.

The "head" of the fish – a slope with an underground sedimentation tank – collects and preliminarily treats the sewage water. The treated sewage then flows down the slope to "body," which contains plants and fish that absorb dirt molecules. After being oxidized and sterilized, the water moves through cobblestones to the fish's "tail," which is a fountain. As visitors step on it, the now-clean water will come out from the ground.

The "living water park" water treatment system has already been used in many parks. It can also be used in residential areas and to water grassland.