If you live on the 30th floor, when you turn on the tap, the water flows smoothly and gently; while the neighbor on the 1st floor, when they turn on the tap, the water also flows gently and does not rush out like a high-pressure water gun, nor does it burst the underground pipes. This is actually a huge challenge in physics and engineering.
    The intense superposition of static water pressure. The "water column nightmare" of 100 meters high. We have learned common physics knowledge: for every 10 meters increase in water depth (height), the water pressure increases by approximately 0.1 megapascals. Assuming a building is 100 meters high (about 30 floors).If a large water tank is directly built on the roof and water is released from it through a pipe to the ground floor by gravity; then at the first floor, the static water pressure at the bottom of the pipe will reach as high as 1.0 MPa, equivalent to 10 atmospheres of pressure, or a water column 100 meters high pressing down on it!
Ordinary household PPR pipes, faucets, and water heater hoses, when subjected to such high pressure for a long time, are extremely prone to cracking or bursting. Not to mention when turning on the faucet, the powerful force can even break the sink. So how do engineers solve this problem?

    The answer is: "Zone water supply" combined with "pressure reducing valve group". The first line of defense: High and low zone division (preventing water from flowing all the way down at once). Super high-rise buildings will never use a single pipe to "dump water all the way down". Engineers will vertically divide the entire building into several water supply areas: Low zone (1-6 floors), directly using the pressure of the municipal tap water itself for water supply. Middle zone (7-15 floors): Sent from the basement's booster pump to the dedicated pipe. High zone (above 16 floors): Supplied with water by the high zone pump group independently.Through zoning, it is equivalent to dividing a 100-meter-high building into several "small buildings", significantly reducing the maximum static water pressure that a single pipe has to withstand.

     Core device: Pressure reducing valve assembly (the "speed bumps" in the pipeline). Even after zoning, within a water supply area (such as from the 7th floor to the 15th floor), there is still a height difference of several tens of meters between the upper and lower floors, and the pressure at the bottom is still relatively high. At this point, a core device installed at the branch point of the pipeline - the pressure reducing valve - needs to be installed. How does the pressure reducing valve work? (Taking the most common proportional pressure reducing valve as an example) The principle of the pressure reducing valve is very ingenious. It does not require any electrical energy; it solely relies on the pressure changes of the water flow to achieve automatic adjustment. The pressure reducing valve is like an automatically scaled narrow passage. No matter how turbulent the water ahead is, at this passage, it can only "limit the flow as needed" pass through.

     Why is it called "pressure reducing valve group"? In construction projects, a single pressure reducing valve is prone to failure due to scale buildup or component aging. Therefore, in the pipe shafts, a pressure reducing valve group is usually installed, which provides multiple safeguards: Filter (front guard): Installed in front of the pressure reducing valve, it intercepts sand and rust in the pipeline to prevent small holes and valve cores from getting clogged. Dual channels/ bypass pipe (backup channel): If the pressure reducing valve breaks down and needs to be disassembled for repair, the bypass pipe can be used to switch to the backup pressure reducing valve to ensure that the residents do not experience water interruption. Pressure gauge (eyes): One pressure gauge is installed in front and another behind the pressure reducing valve. Maintenance personnel can easily determine whether the inlet water pressure and the pressure after reduction are normal by looking at the pressure gauges. Safety valve (last line of defense): Once the pressure reducing valve completely fails and the high-pressure water passes through the barriers, the overpressure safety valve will automatically open to release water and reduce pressure, preventing high pressure from damaging the pipelines of thousands of households.