If the word "rain" or "sewage" is written in the middle of the manhole cover, it means that this is a rainwater well or a sewage well; If the word "fire fighting" is directly printed on the manhole cover, it means that this is a fire fighting manhole cover; If "QD" is written on the manhole cover, it means that this is a strong electric well; If "RD" is written on the manhole cover, it means that this is a weak current well.

The manhole covers on the sidewalk are marked differently. Generally speaking, it is managed by each construction unit according to its purpose. Various signs on the manhole cover represent different responsible units. Municipal underground pipelines include tap water, rainwater, telephone, electric power, street lamps, optical cables, communication, signals, gas and natural gas pipelines. These pipelines and corresponding manhole covers are built and managed by each unit respectively. For example, the rainwater manhole cover is managed by the District Environmental Protection Water Affairs Bureau, the tap water manhole cover is managed by Deepwater Baoan Water Group, and the telecom communication pipe network manhole cover is the responsibility of the telecom company.

What the state requires is that there should be obvious fire signs on the fire manhole cover, and the words "fire protection" are generally printed directly. Fire signs are symbols used to show the characteristics of fire control facilities. It is used to explain the location where buildings are equipped with various fire-fighting equipment and facilities and the location where signs are installed, and to induce people to take reasonable and correct actions in case of accidents. It plays a very good role in safe evacuation, and can help people identify the evacuation position and direction in time more effectively in the case of heavy smoke, and evacuate quickly and smoothly along the luminous evacuation indicator light.