SEWAGE SYSTEM IN INDIA 

A combination of sewer lines and manholes which helps to dispose the sludge away from the owner's property to either a septic tank or a public line is known as sewage system. In this post we will try to focus on some basic points related to sewage system. This post may not be useful for exam point of view, but we are sure that it will be beneficial for interview point of view Etc. 

Some Basic points which a site Engineer or Contractor has to keep in mind while designing a sewage line are as follows :-

  • The water pipes and sludge pipes entering or exiting a building should be on opposite face of a building. This will avoid the accidental interaction of fresh water and sludge. Moreover positioning of both the pipes on a same face of a building has some pshycological problems associated with it. 
  • The sewage line exiting from the owner's property should connect the main line at an angle of 60 Degree with the direction of the main line. It will avoid the back flowing of water up to some extent in case of blockage in Main public line. 
  • Intercepting Traps can also be provided at the Junction of Building sewer and Public Sewer. These intercepting Traps not only eliminate the possibility of foul smells but also check the entry of rodents in to the Building Sewer. 
  • Anti flood Valve can also be installed at such junction where back flowing of sludge from the Main public line to the Building sewer is a possibility. 

A youtube video is also attached to look at the working of one such trap.


Hope this video has clarified the working of Intercepting Trap.


  • After completion of work testing should be first completed before covering the laid sewer line with concrete or any other material. 
  • Manhole should be constructed at any change in the direction of sewage line or at the change of the gradient. In a straight sewer line Manhole should be kept at a proper spacing. 
  • Manhole dimension depends on the depth of the manhole. The dimension of manhole should increase with depth as with increasing depth it becomes difficult for the inspecting person to enter in to the manhole with small dimension. 
  • Drop Manhole should be constructed at locations where Highest level of sludge in public sewer and invert level of Building sewer has a difference in level of around 600 mm. Drop manholes are provided so that workers can easily operate at such location.  
Testing of Sewer Line
We all have read about few tests which are conducted to locate the seepage in the sewage line. Here we are not going in to the theory part as we know that you all are aware about that. We are providing some video links which will help you to understand these tests in better practical way. 
  • Smoke Test
  • Ball Test

Videos for the remaining test will also be updated once found.
This post will be updated regularly. So Plz feel free to ask anything specific related to this post.

Hope you enjoyed the post.