Shapes of non-circular drain

The following are the non-circular shapes, which are commonly, used for sewers

  1. BASKET HANDLE SECTION: In this type of sewer, the upper portion of sewer has got the shape of a basket-handle. The bottom portion is narrower and carries small discharges during monsoon and combined sewage is carried through the full section. This shape of sewer is not generally used at present
  2. CATENARY-SHAPED SECTION: In this type of sewer, the shape of sewer is in the form of a catenary and only gravity force is acted upon this sewer. This is suitable for tunneling work
  3. SECTION THAT IS EGG-SHAPED OR OVOID: This style of sewer is appropriate for transporting combined flow. The main benefit of this style of sewer is that, compared to a circular sewer with the same capacity, it provides a little higher velocity with low flow. However, this portion is more complex to manufacture and less stable than circular sections. Sewers in the shape of an inverted egg provide improved stability and can carry large discharges.
  4. HORSE-SHOE SECTION: This kind of sewer is utilised to transport heavy discharges, including truck and outfall sewers, during tunnel construction. When there is little headroom available for sewer construction, this is also appropriate. The sewer’s invert may be flat, round, or paraboloid, with a semicircular-shaped top and vertical or inclined sides.
  5. PARABOLIC SECTION: This type of sewers are suitable for carrying comparatively small quantities of sewage and economical in construction. The invert of sewer may be flat or parabolic and upper arch of the sewer takes the form of parabola
  6. RECTANGULAR OR BOX TYPE SECTION: The sewage section is stable and simple to build in a rectangular or box shape. It is occasionally employed as a storage tank when it becomes essential to temporarily hold sewage due to the tide.
  7. SEMI-CIRCULAR: This style of sewers has greater hydraulic qualities and is appropriate for building huge sewers with limited headroom.
  8. SEMI-ELLIPTICAL SECTION: This type of section is used for soft soil since it is sturdier and can carry big discharges. Except at low depths, the sewer’s dia may exceed 1.8 metres and it has good hydraulic characteristics.
  9. U-SHAPED SECTION: The shape of this section is the true shape of letter. Or small trench of U shape can be setup in the larger section of sewer. The trench is known as the cunette and adopted for a combined sewer having predominant flow of storm water.


When choosing sewage materials, the following elements should be carefully taken into account.

  1. Price: The price should be fair and reasonable.
  2. Sturdiness: The substance should be sturdy.
  3. Imperviousness: The sewer’s construction material must possess this property.
  4. Abrasion Resistance: The material must be sufficiently resistant to abrasion brought on by grit moving at a high speed.
  5. Corrosion resistance: Due to the sewage’s corrosive properties, the material should be able to offer corrosion resistance.
  6. Weight: To facilitate handling and transportation, the material should be moderate in weight.
Shubhajna Rai
Shubhajna Rai

A Civil Engineering Graduate interested to share valuable information with the aspirants.

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