01 JAN

French drains and septic tanks by-laws

Written by Drain Ratz Plumbing , Posted in Sewage Treatment Solutions

What are the french drain and septic tank municipal by laws?

Before installing any underground features like sewerage lines or even septic tanks or french drain systems, always call your local Municipality First!

Once you have received the proper permit for your septic tank and french drain/soak away, we are good to go. If unsure about the rules and regulations of septic tanks and french drains/soak aways, Drain Ratz Plumbers & Builders are just a call away.

As a general policy the municipality is only prepared to permit the installation of a french drain/soak away when the soil conditions are ideal.  The municipality reserves the right to insist on the removal of a septic tank and french drain/soak away at any time in their sole discretion.


  1. Size of plot must be considered. (900 square metres)

  2. The soil must be suitable for the installation of a french drain/soak away. In more than one case the municipality has allowed for the installation of a septic tank but not a french drain/soak away. If this is a case, the most long term cost effective solution would be to install a treatment plant. Drain Ratz Plumbers & Builderswould be able to assist you as they are leaders in this field.

  3. There must be a stable water source.

  4. The septic tank and french drain/soak away if feeding a dual or single pipe line must be excavated 2 to 3m away from the building it services.

  5. The inlet and the outlet must be accessible from the inspection covers in the top of the tank.

  6. The Director of Health Services may condone a combined drainage system depending on the absorption capacity.

  7. Most important rule: septic tanks must be watertight.

  8. Most sites are comfortably fitted with durable plastic tanks and it is recorded that the precast concrete and the everite asbestos cement tanks have been approved by the municipality and may be permitted in certain circumstances but not in conjunction with a combined drainage system.

  9. When a sewerage system is installed, all buildings must be connected to the sewer, septic tanks and french drains/soak away closed down.

    New rules for septic tanks and french drains 

(Old fashioned way of just digging a hole and filling it with building rubble and stones – Not permitted, according to the new rules and regulations.) Follow these below and you will be safely on your way of having an approved unit.

  1. A trench-style french drain/soak away with walls of cement blocks,hollow tile brickwork and cavities to be in tile horizontal plane.

  2. Standard size: 600 mm x 600 mm x 7 5mm paving slabs. The trench must have a surround of stone/half burned bricks and width must be 450 mm and to the full depts. Of the walls. Should your permit, stipulate differently, implement that which is stated on your permit.

  3. Should have a system of agricultural drainpipes guided by the circumstances, not less than 3 metres from any building or boundry.

  4. Pit: should be round constructed with cement blocks or hollow clay tiles with cavities in the horizontal plane. The pit size should be 2 metres in diameter and dept as circumstances indicate. The pit should have reinforced slab over the top to contain a 600 mm x 150 mm inspection cover.

  5. Most important factor: it must be parallel to the contours of the ground.

  6. The length of the french drain/soak away must be determined in relation to the soil and general site conditions and the number of appliances seved by the french drain/soak away.

Low lying ground

If you have a low lying ground with a high water table, the municipality may allow the round/circular soakage pit Subject To Terms & Conditions.

  1. The level of the site around the french drain/soak away to be considered. It must be raised above the level attained by storm water.

  2. Use a channelling system like gutters, down pipes to carry all roof water away from the french drain/soak away to the nearest road.

  3. Buildings must be damp proof at least 2 courses above the level of the filling.

  4. French drain/soak away must be an adequate size, the depth being dependent upon the summer water table in any particular area.

  5. There must be a clearance level of at least 25rnrn between the invert level of the final discharge pipe into the french drain/soak away and the maximum water table in the french drain/soak away pit.

  6. In cases where your french drain/soak away is not functioning properly, and you have an arrangement with the municipality for the removal of wastewater, a watertight sump may be permitted in placer of, or in addition to a french drain/soak away.the watertight sump should be able to capacitate 4500lites, it must be properly ventilated and situated not more than 12 metres from a vehicular approach to permit of future servicing which will be the responsibility of the owner.

For a job like this, it is always wise to contact the professionals and here at Drain Ratz Plumbers & Builders . We are always willing to assist, whether it is a New installation or a simple repair!


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