What floor does the secondary water supply start from 18?

High-rise residential buildings all adopt secondary water supply.

The secondary water supply for high-rise residential buildings generally starts from the 5th or 6th floor, because the municipal water supply pressure can generally meet the water supply requirements of1~ 6th floor, and secondary pressurization is required above the 7th floor.

The water supply mode of high-rise water supply is generally through district water supply.

High-rise secondary water supply equipment: non-negative pressure water supply equipment

Bohai water supply