The “Water Well” Under The City

In the underground world of the city, there are densely crisscrossed sewage pipe networks, which are like the city's "digestive system", silently carrying the task of transporting domestic wastewater. In this system, there is a special structure that is often overlooked but is crucial - the waterfall. It is like a "speed bump" for sewage pipes, silently guarding the safety and stability of the pipe network.

I. What is a waterfall?

A drop well is a vertical or stepped well structure, usually built at locations where there is a large height difference in sewage pipes. When sewage flows from a high pipe to a low pipe, the water flow rate will increase sharply due to gravity, which may impact the downstream pipe and even cause the pipe wall to rupture. The drop well converts the "rushing" of the water flow into a "slow walk" by dissipating energy in sections, thus avoiding damage to the pipe.

II. How does a waterfall well work?

1. Energy dissipation and deceleration

After sewage enters the waterfall, it will experience a "free fall" or "step drop". Through repeated impacts and splashes of the water flow, the kinetic energy is gradually consumed, and the flow rate changes from "turbulent" to "gentle".

2. Preventing cavitation

High-speed water flow may cause gas explosion in the pipeline (cavitation phenomenon). The drop well reduces the risk of gas accumulation by reducing the flow rate.

3.Debris buffer

The sand, gravel and garbage in the sewage settle in the waterfall to avoid directly impacting the downstream pipes or water pumps.

III. The “hidden design” of the waterfall

●Vertical pipe type: water flows through vertical pipes, suitable for scenes with large height differences.

●Stepped type: multiple steps dissipate energy layer by layer, common in areas with complex terrain.

●Energy dissipation pool type: a pool is set at the bottom of the well to absorb impact force through a water cushion, similar to a "water bed".

Modern waterfall wells are often equipped with grilles or sedimentation tanks to further intercept garbage and reduce the pressure on Sewage Treatment Plants.

IV. Why should we pay attention to it?

1.Protect the pipeline network: reduce pipeline wear, extend service life, and reduce the risk of urban waterlogging.

2.Environmental protection guard: prevent sewage leakage from polluting soil and groundwater.

3.Operation and maintenance tips: Regularly cleaning the sediment in the well (such as silt, plastic bags) is the key to maintaining its function.