Soak Pit Design. What you need to know about Soak Pit.

Soak Pit Design. What you need to know about Soak Pit.

Soak Pit Design. What you need to know about Soak Pit.

 Soak Pit Design

Soak Pit Design: The waste water generated in the house from kitchen and  bathrooms has to be disposed. If it is disposed in open it not only creates unhygienic conditions, foul odors but also invites epidemics and diseases. Soak pit is ideal.  A Soak Pit is a covered, porous-walled chamber that allows water to slowly soak into the ground. Pre-settled effluent from septic tank is discharged to the underground chamber from where it infiltrates into the surrounding soil.

Design of Soak Pit

Soak Pit Design


A layer of sand and fine gravel is spread across the bottom to help disperse the flow. Depth should be between 1.5 and 4m deep, but never less than 1.5m above the ground water table. The Soak Pit is filled with coarse rocks and gravel. The rocks and gravel will prevent the walls from collapsing, but will still provide adequate space for the waste-water.

How Soak Pit Design Work

As waste-water 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

Soak pit with installed PVC pipe

Soak pit are best suited to soils with good absorptive properties; clay, hard packed or rocky  soils are not appropriate.


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 depend on soil with a sufficient absorptive capacity. They are not appropriate for areas that are prone to flooding or have high groundwater tables.

Health Aspects

The technology is located underground and thus, humans and animals should have no contact with the effluent. The Soak Pit is located a safe distance from a drinking water source (ideally 20m).  The Soak Pit is odourless and not visible.

Soak Pit Design

Soak Pit Schematic Diagram A-masonry ring B-stone or brick aggregate C-brick chamber D-30cm thick outer casing with coarse sand E-effluent from septic tank



  • the effluent should be clarified or filtered well to prevent excessive build up of solids.
  • The Soak Pit should be kept away from high-traffic areas.
  • Particles and biomass will clog the pit so need to be cleaned or moved.
  • For future access a removable lid should be used to seal the pit.

READ: 7 Tips to cut construction costs (Helpful Guide)

 Advantages of Soak Pit

  • Can be built and repaired with locally available materials.
  • Small land area required.
  • Can be built and maintained with locally available materials.
  • Simple technique for all users.

Disadvantages of Soak pit

  • Pre-treatment is required to prevent clogging, although eventual clogging is inevitable.
  • Negatively affects soil and groundwater properties.

Also Read: Construction materials and  current market prices

HPD Consult


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