I wonder why sewage flows to the treatment plant. Is it because there is a slope in the sewer? However, if you gradient at a very long distance, it will be very deep underground, and it will not flow smoothly with a slight slope.

Unlike the water supply system, the sewer also has to drain solids. In principle, natural flow is planned because the pipeline is bent like a water supply that drains Shimizu, or if it flows with pressure, the pipeline is clogged or damaged.

The slope of the pipeline for natural flow is that if it is loose, earth and sand and dirt can easily accumulate in the pipeline, and if the slope is steep, the flow velocity increases and the pipeline is easy to wear, so an appropriate slope is determined. You.

If the main line becomes too deep during the process of sewage flowing from the branch line pipeline to the main line and the water reclamation center, a relay pumping station is set up to pump it up and let it flow down naturally again.