Do you know the differentiation of manhole covers?

In Japan, most manhole covers have unique numbers and are incorporated into the sewer management system. Taking Tokyo as an example, the Tokyo Sewerage Bureau has assigned a unique number to each manhole cover. When it expires, it should be repaired and replaced. Most manhole covers in Japan are maintained by private public utility companies.

In addition, the pattern design and shape on Japanese manhole covers also vary by region and department. The sewers managed by the governments at all levels of the city, district and town are distinguished by the city flower, district flower and town flower on the manhole cover. If the manhole cover is damaged and needs to be repaired, the responsible party can be identified immediately. Individually owned sewers will be marked with the word "private" and the owner's surname on the manhole cover to distinguish them. The manhole covers of fire hydrants are mostly rectangular or engraved with cartoon patterns of firefighters.

Japan is a country with frequent natural disasters, and there are "emergency shelters" near residential areas. In addition to arrows indicating the direction, the manhole covers around some shelters are also painted with colors. The yellow arrows indicate within 200 meters of the shelter, while the red ones indicate within 100 meters.