A septic tank is only as good as the way it goes into the ground. Septic tank installation covers far more than digging a hole: the layout has to be approved, the tank bedded and levelled, the pipes laid to fall and the effluent sent to a drainage field that the soil can absorb. Tell us about your plot and the tank you have in mind, and drainage contractors who work in your area will send you a quote directly.
Approval and plans before any digging
In most municipalities a septic tank is a building work, so the layout goes on your plans and must be approved before you dig. The municipality will usually want a site plan showing the tank, the drainage area, the house and any boreholes, and sometimes a percolation test result. Drainage design in South Africa follows SANS 10400 Part P, which sets out in general terms how wastewater must be collected, treated and disposed of safely.
Some areas also ask for a letter from the water authority, or for a registered plumber to sign off the work. Ask the contractor early what your municipality requires, and have a look at septic tank design to settle the size first.
How the installation is done
A typical installation follows the same order on every site:
- Excavation: a hole slightly wider than the tank, deep enough for the inlet to sit below the house drain with a fall of about 1 in 50 to 1 in 40.
- Bedding: a compacted layer of sand or fine gravel, levelled so the tank does not tilt or settle.
- Setting the tank: lowered by hand, truck crane or excavator, then checked for level in both directions.
- Pipework: a 110 mm inlet pipe, tee fittings, an outlet to the drainage field and a vent pipe above roof height or garden level.
- Backfilling: sand in layers around the sides while a plastic tank is filled with water to stop it floating or deforming.
The drainage field and safe distances
The tank only treats part of the waste. The liquid that leaves it must soak away through a soakaway or french drain, so the position and soil type decide how big that field must be. Clay, high water tables and shallow rock all reduce what the ground can take.
Keep the tank and field well away from sensitive points. As a general guide, aim for at least 30 m from a borehole or well, several metres from buildings and boundaries, clear of driveways that carry heavy vehicles, and away from streams and flood lines. Your municipality will give the exact distances that apply.
What affects the installation price
Quotes differ because sites differ. Rock or a high water table slows excavation, a long run between house and tank needs more pipe and manholes, and a large drainage field adds gravel and labour. Compare quotes on what is included, such as plans, the tank, the field, the vent and the compaction, and see septic tank prices for typical figures.
What to include in your request
- Plot size and where the house drain leaves the building
- Number of bedrooms or people using the system
- Distance to any borehole, well, boundary or stream
- Soil type, rock or a high water table if known
- Whether municipal approval and plans are done or needed
Septic Tank Installation for different properties
- Houses: a new tank and drainage field for a house built or extended away from the sewer
- Smallholdings and plots: a full system on a smallholding, with a larger field and a long pipe run
- Estates and complexes: tanks and drainage laid for each stand or shared units before the units are occupied
- Farms and game farms: separate systems for the homestead and worker housing, kept clear of boreholes
- Lodges, guesthouses and venues: larger tanks and fields sized for guest numbers, often with a treatment plant
- Restaurants, shops and offices: approved systems for shops, restaurants and offices outside the sewer network
- Schools, churches and clinics: large tanks for schools and clinics, with plans signed off by a professional
- Factories, mines, sites and events: site tanks for construction camps and workshops, installed to a set programme
Frequently asked questions
How much does septic tank installation cost?
Do I need approval to install a septic tank?
Can I install a JoJo septic tank myself?
How long does an installation take?
Septic Tank Installation by province and city
- Johannesburg
- Pretoria
- Centurion
- Midrand
- Sandton
- Randburg
- Roodepoort
- Krugersdorp
- Randfontein
- Germiston
- Boksburg
- Benoni
- Kempton Park
- Alberton
- Vanderbijlpark
- Vereeniging
- Durban
- Pinetown
- Pietermaritzburg
- Richards Bay
- Newcastle
- Ladysmith
- Gqeberha (Port Elizabeth)
- East London
- Kariega (Uitenhage)
- Mthatha
- Cape Town
- Bellville
- Paarl
- Stellenbosch
- George
- Worcester
- eMalahleni (Witbank)
- Middelburg
- Secunda
- Mbombela (Nelspruit)
- Rustenburg
- Brits
- Klerksdorp
- Potchefstroom
- Mahikeng
- Polokwane
- Tzaneen
- Kimberley
- Upington
- Bloemfontein
- Welkom
- Sasolburg