The invention provides a rainwater and 
sewage gravity 
potential energy collecting device. The rainwater and 
sewage gravity 
potential energy collecting device comprises a 
water turbine, a roof drainagepipe, a second-floor drainage 
pipe and a first-floor drainage 
pipe, wherein the 
water turbine main shaft, the roof drainage 
pipe, the second-floor drainage pipe and the first-floor drainage pipe sequentially sleeve from inside to outside by taking the central axis of the 
water turbine main shaft as the center, a water 
turbine is sequentially provided with an upper 
impeller, a middle 
impeller anda lower 
impeller from top to bottom along the main shaft, and the distances of the positions of the highest points of the upper impeller, the middle impeller and the lower impeller lower than the bottom surfaces of an upper middle floor drain pipe and a lower middle floor drain pipe are 10-20 mm, the central axis of a 
sewage diversion pipe in one building is located on the same horizontal plane with the intersection point of the outer wall of the drainage pipe of the building and the highest point of the middle impeller, and the central axis of a second-floor sewage flow guide pipe is locatedon the same horizontal plane with the intersection point of the outer wall of the second-floor drainage pipe and the highest point of the upper impeller. Scattered distribution is collected in the rural and town energy-saving emission reduction resource recycling field, the gravity 
potential energy of the rain sewage and the small-power distributed energy 
station can be continuously discharged, and the device can be used. The rainwater and sewage gravity potential energy collecting device is little in investment, convenient to install, and compact in arrangement, and the converting efficiencyfrom the gravity potential energy to the rotating energy is 75%.