In China's residential areas, every 400 to 600 meters should have a public toilet. That's a four-to-seven-minute walk. They are not only for tourists, but for residents who live in Beijing's hutongs, narrow and meandering alleyways. Liang Ji, a student at Tsinghua University, has renovated over 600 public toilets in Beijing's downtown district, but getting these facilities to a respectable standard is a difficult task.