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What do you understand about Soak Pit??


  • A soak pit is known as soak way or leach pit, is a covered, porous-walled chamber that allows water to slowly soak into the ground.
  • Soak pit are best suited for soil with good absorptive properties; clay, hard packed or rocky soil is not appropriate.
  • Pre-settled effluent from septic tank is discharged to the underground chamber from where it infiltrates into the surrounding soil.
  • Soak pits are used the same way as leach fields, but require less space as well as less operation and maintenance.

Difference between Soak Pit and Septic Tank

  • Soak Pit generally a big whole digged under which the red bricks along with cement is put like concrete at the end of the dig leaving the side walls as it is soak the drainage water.
  • Septic tank will be constructed comparatively smaller size than soak pit with all the walls built and also the floor is put with cement and there will be opening and a door to open and the water will be drained using equipment along with transport tanks the sewage cleaning board of state government or even the private sewage board.
  • It will be in houses where the drainage system is not available or provided by state corporation or panchayat union of the respective places.

Health Aspects

  • The technology is located underground and thus, humans and animals should have no contact with the effluent.
  • The soak pit is not used for raw sewage, and as long as the pervious collection and storage/treatment technology is functioning well, health concerns are minimal.
  • The soak pit is odorless and not visible, it should be accepted by even the most sensitive communities.
  • The soak pit is located a safe distance from a drinking water source.

Design Consideration

  • A layer of sand and fine gravel is spread across the bottom to help disperse the flow.
  • The soak pit should be kept away from high-traffic areas so that the soil above and around it is not compacted.
  • Depth should be between 1.5 to 4m deep, but never less than 1.5m above the ground water table.
  • To allow for future access, a removable lid should be sued to seal the pit until it needs to be maintained.
  • The soak pit is filled with coarse rocks and gravel.
  • It should be located at a safe distance from a drinking water source.
  • The rocks and gravel will prevent the walls from collapsing, but will still provide adequate space for the wastewater.

Working Principle

  • As wastewater percolates through the soil from the soak pit, small particles are filtered out by the soil matrix and organics are digested by micro-organism.
  • Soak pit are best suited to soils with good absorptive properties; clay, hard packed or rocky soils are not appropriate.


  • The soak pit should be kept away from high-traffic areas so that the soil above the around it is not compacted.
  • The effluent should be clarified or filtered well to prevent excessive build up of solids.
  • For future access a removable lid should be used to seal the pit until it needs to be maintained.
  • Particles and biomass will clog the pit so need to be cleaned or moved.


  • A soak pit does not provide adequate treatment for raw wastewater and the pit will clog quickly.
  • A soak pit should be used for discharging pre settled black water or grey water.
  • Soak pits are appropriate for rural and suburban settlements.
  • They can be used in almost every temperature, although there may be problems with pooling effluent in areas where the ground freezes.
  • They depend on soil with a sufficient absorptive capacity. They are not appropriate for areas that are prone to flooding or have high ground.


  • Can be built and repaired with locally available materials.
  • Power conservative
  • Low capital cost, low operation cost
  • Small land area required
  • Simple technique for all users
  • Recharging groundwater bodies
  • Can be built and maintained with locally available materials.


  • Pretreatment is required to prevent clogging, although eventual clogging is inevitable.
  • Negatively affects soil and groundwater properties.
  • Difficult to realize in cold climate.
  • Should be avoided for high daily volumes of discharged effluents.

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