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About Sewage

A good sewage system is essential for a healthy environment. Duraco caters for all your sewerage needs.

Products Details

Duraco pioneered the manufacture of prefabricated polyethylene septic tanks in Mauritius since 1997. Our septic tanks comply with the requirements of the Waste Water Management Authority. Duraco’s complete range of septic tanks take quality and flexibility to the next level.

A septic tank is a key component of a sewage system and is important for public health and environment.

Effluent flows from the toilet through the sewer piping network into a tank where liquids, fats, oils and solids are separated. Bacteria in the septic tank consumes the organic matters and leaves behind a treated effluent which flows to an absorption pit.


  • Manufactured from 100% virgin material
  • A superior dome structural integrity and design for durability
  • Reinforced structural brace ring and ribs
  • A riser shaft that provides greater flexibility for installation
  • Easy to transport and install
  • Rotationally moulded, One-Piece Construction
  • Rust and corrosion free/ Excellent Chemical Resistance / Pre-Plumbed / Ready for installation
  • Watertight Lid - Duraco septic tanks come outfitted with a UV stabilised domed lid.
  • Proven track record of trouble free service.
  • Available colours - Natural or black.
  • Approved by the Waste Water Authority.


  • 1800L - Max 5 persons
  • 3000L - Max 8 persons
  • 4700L - Max 13 persons


Average Waste-water generation per person – 180 Litres/day

Retention Time for Treatment and Reaction – 48 hours (2 days)

Volume Required for Treatment = Volume of Waste-water Generated.

Volume of Waste-water generated in 48 hours = No. of Person x Wastewater Generated Per Person x 2

For example: A family of 5 persons will require a 1,800 L Septic Tank (5 x 180 Lt  x 2)

Waste-water (black water from Toilet) enters the septic tank through a 110mm diameter pipe on which a venting pipe (Air Vent) is connected. For each flush, waste-water flows down through the pipe picking up oxygen through the air vent pipe. As waste-water enters the septic tank, it is segregated in three segments: Segment A: Upper part of the septic tank consists of Fats, Oil and Grease (FOGs). In this zone, aerobic bacteria gradually degrade the FOGs. Segment B: Middle part of the Septic tank is the Aerobic zone consisting of suspended matter, oxygen and aerobic bacteria. In this segment, the organic matter is degraded to form Carbon dioxide and Water. Carbon dioxide diffuse out through the Air vent. Segment C: Anaerobic zone consist of sludge (mixed of settled solid degradable organic matter and dead cells of bacteria) and anaerobic bacteria. Anaerobic bacteria degrade the organic matter in the low concentration of oxygen. In the anaerobic process, carbon dioxide, hydrogen sulphide, methane and water is formed. These gas get diffused out through the air vent pipe. The treated water passes through the pre-filter basket into the absorption pit.


Step 1: Excavation: -

Dig to a depth that will provide a maximum of 300 mm of fine soil over the top of the Septic tank.

Allow 230 mm around the tank.

Step 2: Bedding: -

Allow for a minimum of 150 mm of compacted bedding material rock sand. Bed the septic tank and make sure it is placed levelled.

The septic tank is supplied with PVC sleeves [internal diameter 110 mm] at the inlet and outlet. The inlet and outlet pipes should be glued to the sleeves using standard PVC glue.

Step 3: Backfilling: -

Ensure the tank lid is properly screwed on the tank manhole. Fill the tank with water through the inlet as you backfill, keeping the water level even with the backfill level. This will prevent possible distortion of the tank and its manhole. Do not remove the lid until the end of the backfill process.

Backfill in layers of 200 mm at a time and properly compact each layer. Ensure to compact each end first. Tamp and compact the backfill under the inlet and outlet before fixing the pipes.

 Maximum backfill over the top is 300 mm. Mound fine soil over the top to provide positive drainage

NOTE: In case the septic tank needs to be installed with more than 300mm of soil above its top, it must be protected by a heavy duty concrete slab, without resting on the septic tank. THE SLAB MUST REST ON FIRM SOIL AROUND THE TANK


Step 4: Septic Extension: -

In case the manhole screwed lid doesn’t reach the ground level, a septic extension will be required. Install the extension to the manhole outlet before starting the backfill process. Make use of our septic extension EXCLUSIVELY. The screwed lid supplied with septic will fit the septic extension.


Step 5: Leaching Field or Drain Field Material: -

The home sewer drain needs to slope at least ¼ inch per foot downhill to the inlet of the septic inlet and the outlet pipe must cater for a downhill slope of 1/8 inch per foot to the absorption pit or the leaching field. The absorption pit should be at a distance of not more than 3 m from the septic and its volume must be at least similar to that of the septic tank.


  • To keep a septic tank functioning properly, it is advisable to have the septic tanks pumped every five years.
  • lf the septic tank has not been utilised for a long period, it is advisable to flush toilets several times to re-activate the aerobic process of the septic tank.


Failure to comply with the points below voids the warranty

  • Do not install any tank in water saturated clay or in high water table. The tank may collapse and its content will escape.
  • Tanks are not fire-resistant. Do not store them near an open flame or heat in excess of 180°F,
  • Do not install any tank under the path of vehicles or heavy equipment unless protected by a heavy duty concrete slab, without resting on the septic tank.
  • When the septic tank is pumped for normal maintenance; it should be refilled immediately.
  • Our septic tanks are designed only for use as underground tanks.
  • Protect the tank from sharp objects which could puncture it and cause leakage.
  • Avoid abusive use of detergent