Septic Tanks

Septic Tank

ST3100 LITRE - $2,500.00

Dimensions: 2450L x 1640W x 1665H

ST4550 LITRE - $3,525.00

Dimensions: 3250L x 1640W x 1665H

Optional 530mm Riser - $315.00

Delivery - $150.00


Installation Guide & Care Instructions


Read this manual thoroughly to ensure all procedures are understood and materials needed are available.


1. Select site

  • Contact relevant authorities before digging to locate all underground cables and pipes
  • Determine the best location of the tank taking into account existing underground services, excavation required, location of blackwater run and heights into tank and outlet fall to drain.
  • Is the tank excavation hole far enough away not to impact on foundations and adjoining structures? Where no regulations exist the distance of the excavation from any structure should be a minimum of 2 times the depth of the excavation.
  • • Consult with a Geotechnical Engineer if you have any questions about possible influence of excavation on surrounding structures
  • Must not be installed where there is a possibility of water table exceeding half the height of the tank

2. Excavation

  • Excavate hole according to dimensions of tank and in accordance with Engineers report
  • Excavation slopes should be a minimum of 30 degrees
  • Hole depth should be a minimum of 1675 below finished pavement / lawn level
  • Remove all loose soil from base of hole, and add 100mm of sand or crusher dust and compact to a firm level pad.
  • Be aware of the safe working practice for working in excavated holes.
  • Hole dimensions at the base should be a minimum of 200mm larger in width and length of the tank.

3. Positioning Tank

  • Using the top lifting points for stability, lift tank into place by use of a backhoe or excavator.
  • The Tank has 4 feet for stability but extra chocking may be necessary depending on conditions
  • Using the access hole for a guide, level tank in both directions

4. Backfilling

  • Before commencing backfill, fill the tank with water up to the half way mark.
  • The backfill material around the tank must be compacted in layers not exceeding 200mm. Use only hand held vibrating plate compactors in the compaction process.
  • Use cohesionless material such as sand, crusher dust, 6mm FCR etc. as a backfill material in the effective zone as shown. The material should be a minimum density of 18KN/m3 and maximum density of 20KN/m3.

5. Final hookup

  • Ensure all caps and overflows are sealed prior to backfilling the excavation and check all connections.
  • Apply 20mm silicone bead around the groove in the top of the access hole and fasten lid down with tek screws.
  • If a riser is to be used, fasten riser in from the inside with silicone and tek screws and then fit lid.


Much effort and thought has gone in to the design of this product, and every precaution has been taken to ensure the customer ’s health and safety. The following points need to be carefully considered:

  • Use a qualified plumber/installer to install and fit-up tank.
  • When lifting tank in to place use the appropriate lifting lugs on the tank and lower evenly into hole. Do not manhandle tank in to place or try lifting manually as injury could occur.
  • Once installed, never leave tamper-proof lid off tank. This is a serious hazard to young children, personnel and animals, and could result in death by drowning.
  • All Worksafe regulations and safe work procedures should be adhered to when installing your septic tank. Never enter the tank at any time without adhering to all guidelines and protocols of relevant confined space entry warnings and directions.

IMPORTANT It is the responsibility of the owner to ensure proper installation and maintenance of the underground tank. Polymaster will not be held responsible for any loss, injury or death resulting from a failure to observe all safety and installation requirements or safe working procedures

Care of your Septic system Owners reference

Polymaster septic systems

Septic systems are ‘on site’ individual wastewater systems that use the soil to absorb and naturally treat wastewater flows. They are typically used where centralised sewerage treatment is impractical or not available.

A septic system uses bacteria to break down the waste and therefore it is important that you do not use cleaning products or dispose of any product down the drainage system that will kill bacteria.

Items to watch out for are:

  • Products that contain chlorine or ammonia
  • Fats and greases
  • Non-degradables such as disposable nappies, sanitary napkins, cat litter, plastics etc.
  • Poisons like petrol, paint, thinners, pesticides etc.
  • Excessive food scraps

There is a range of biological cleaning products that are made specifically


It is normal in the first few weeks of operation for your septic tank to produce some odours which after a short time will disappear or be replaced with a slight earthy smell. If there is much change to your situation you may find you have used some chemicals or have put a large amount of washing through the laundry. If this is the case the unit will correct itself in a few days; try to spread the laundry evenly over the week as much as possible.

Remember: less water used means less water to be treated and disposed of.

Ground Maintenance

Septic systems have a network of drainage pipes that allows the wastewater to seep into the subsurface soil. The area over this ‘drainfield’ should be left undisturbed with only a mowed grass cover. Divert excessive ground/stormwater away from this area and be aware that roots from nearby trees or shrubs may clog and damage your drain lines. Do not allow anyone to drive or park over any part of the drainage system.

Desludging your septic tank

Septic systems overtime will build up with an excess of accumulated solids that should be pumped out every 3-5 years. This depends a lot on the volume that is put through the tank so varies greatly on applications.

Make sure the tank is pumped out by a licensed liquid waste contractor, please see the local council in your area about any special EPA regulations.

Always leave a small volume of effluent in the tank to ensure tank does not float up or become dislodged. Bacteria levels in the tank will restore once wastewater enters the system again.

For more information about maintenance or inspection of your Polymaster Septic System contact the plumber who installed your tank or the local council.

Please Note: Never allow anyone at any time to enter the septic tank as it is a confined space and once operating is an extreme health risk.

Thank you

Thank you for purchasing a Polymaster Septic Tank. The purpose of a septic tank is to provide a complete septic tank system which complies to Australian Standards, and gives you guaranteed performance.

Stringent testing

Some of the stringent testing and standards we have complied to are listed below:

  • Complies with AS/NZS1546.1:2008 for the construction of septic tanks.
  • Tanks have been designed using engineering design methods including finite element analysis.
  • By following the installation requirements. You will find this tank will give you many years of trouble free service.

Warranty details

Polymaster septic tanks come with a 10 year manufacturer’s warranty. It also meets with accreditation guidelines designed for a service life of 15 years.