What is Drainage work?

Get to know the regulation

Under Part 4 of the Plumbing Regulations 2018, Drainage work is the construction, installation, replacement, repair, alteration, maintenance, relining, testing or commissioning of any part of:

  1. a below-ground sanitary drainage system from the above-ground sewage or waste pipes to and including:
    1. the land application system
    2. the connection to a holding tank; or
    3. the connection with the discharge reticulation system exclusively vested in an authority that has a sewerage district under the Water Act 1989;
  2. a below ground stormwater drainage system from the above-ground stormwater pipes to the point of discharge
  3. any design work that is incidental to, or associated with, any work described in Regulation 15(1)(a).

Drainage work does not include:

  1. the construction, installation, replacement, repair, alteration, maintenance, relining, testing or commissioning of:
    1. a subsoil drain for the sole purpose of subsoil water collection; or
    2. stormwater pits, channels that are grated or below-ground storage or retention tanks; or
  2. any excavation of trenches, excavations using trenchless technology or directional boring.

Typical Drainage work

Drainage plumbing removes sanitary waste or stormwater from a site. Experienced Drainage plumbers typically do the following work (and more):

  • prepare trenches and laying of stormwater and sanitary drains
  • installing, connecting and testing underground sewerage treatments systems such as septic tanks and pressurised treatment systems
  • installing grease traps
  • installing drains, while ensuring the use of adequate support systems
  • cutting and sealing disused underground drains
  • repairing and replacing below ground drains
  • installing onsite disposal systems such as mulchers, neutraliser tanks, above ground grease interceptors and septic tanks
  • installing overflow provisions, including overflow relief gullies and reflux valves
  • installing drainage vents and inspection shafts
  • locating and clearing blockages in underground drains.

What do Drainage plumbers need to know and do?

A drainer’s work is critical to the efficient installation and design of below ground sanitary and stormwater systems within and from a building. So, drainage plumbers need critical knowledge and skills to ensure the installation of sanitary/stormwater systems protect the health and safety of the building occupants. What does this mean for you?
As a registered practitioner, you must be able to understand and apply the compliance requirements of Drainage plumbing work. These requirements include:

  • AS/NZS 3500 National Plumbing and Drainage Code.

To undertake Drainage work to a safe and competent standard, you must also be able to:

  • read a site/ building plan including a property service plan and interpret the plan’s symbols and terms to identify drainage systems and requirements
  • install trench support when drains are installed at a depth of 1.5 m or deeper, move the support along the trench, and remove the support safely.

What competencies and experience do you need?

The VBA publishes a set of units of competency for each class of plumbing work. Each unit of competency describes a work outcome, all the knowledge and skills needed to do the work to the expected standard, and how they should be assessed.

The VBA uses the units of competency to assess your skills and experience if you apply to register in a class of plumbing work.

To be eligible to register in the Drainage class, you must be able to show:

  • you have the relevant competencies plus recent and relevant experience in work related to the Drainage class of plumbing, or
  • you have knowledge equal to the competencies for Drainage work of Certificate II or higher, plus at least two years of experience while working under the supervision of a plumber who is licensed in Drainage work.

You must also prove you successfully completed an accredited training course in Install Trench Support.

Before applying for registration or licensing, please read the current approved units of competency for Drainage.

Units of competency for Drainage work


Common units

A common set of eight units are required for all of the main classes, except Refrigerated air-conditioning and Type B gasfitting.

  • Carry out interactive workplace communication (CPCPCM2039A)
  • Read plans and calculate plumbing quantities (CPCPCM2040A)
  • Work effectively in the plumbing and services sector (CPCPCM2041A)
  • Carry out WHS requirements (CPCPCM2043A)
  • Handle and store plumbing materials (CPCPCM2045A)
  • Use plumbing hand and power tools (CPCPCM2046A)
  • Carry out levelling (CPCPCM2047A)
  • Provide basic emergency life support (HLTFA211AP)
Class specific
  • Carry out simple concreting and rendering (CPCPCM2054A)
  • Locate and clear blockages (CPCPDR2021A)
  • Install domestic treatment plants (CPCPDR2022A)
  • Maintain effluent disinfection systems (CPCPDR2023A)
  • Install stormwater and sub-soil drainage systems (CPCPDR2024A)
  • Drain work site (CPCPDR2025A)
  • Install prefabricated inspection openings and enclosures (CPCPDR2026A)
  • Plan layout of a residential sanitary drainage system (CPCPDR3021A)
  • Install below ground sanitary drainage systems (CPCPDR3022A)
  • Install on-site disposal systems (CPCPDR3023A)
  • Install trench support (RIICCM210A)
  • Install pre-treatment facilities (CPCPSN3025A)


Common units
  • Establish legal and risk management requirements of small business (BSBSMB401A)
  • Carry out work based risk control processes (CPCPCM4011A)
  • Estimate and cost work (CPCPCM4012A)
Class specific
  • Design and size sanitary drainage systems (CPCPDR4011B)
  • Design and size stormwater drainage systems (CPCPDR4012B)
  • Design and size domestic treatment plant disposal systems (CPCPDR4013B)