Promax Underground Tank 30000L 1.9m dia

The Promax Underground Stormwater / Wastewater tanks are suitable for the retention or detention of stormwater or the storage of potable water.

The plastic stormwater tanks are fully tested and designed to withstand ground and water pressure at depth.The Promax Underground retention tank is engineered by geotechnical experts and Finite Element Analysis tested (FEA).

Distinctive Benefits for:

  • Stormwater retention, detention and Wastewater storage
  • Large range from 10000 lt to 30000 lt with 1.9m diameter (larger on request)
  • Suitable to be installed under driveways, footpaths, car parks, forecourts and much more
  • Save time and money with multiple inlet/outlet plumbing ports
  • Vehicular Traffic - Tested to AS/NZS 2566:1-1998 with a load rating of 28kpa. 
  • Non Vehicular Traffic - Tanks in non-critical areas can be placed at any depth that is required
  • Certification to AS/NZ 4766 - Polyethylene storage tank standard

Click here to download full installation guide

NZ Regional Stormwater Management Requirements

NZ Councils Approved List of TP58 Writers


Code Description Capacity(L) Diameter(mm) Length(mm) Weight(kg)
PMXUT30000 Promax Underground Tank 30000L 1.9m dia 30000 1900 12540 1800

We recommend contacting your plumber - he can advise on planning the project and ensuring your plans will work.

Click here to download Promax Big Tank Installation Guide PDF.

Click here to download Underground Tank and Septic Tank Installation Guide PDF.

If you would like to install the tank yourself this video will be very helpful:

Promax Corrugated tanks are so tough you can bury them up to 1 metre in the ground - and they still retain their 20 year warranty!

Often a project can have height restrictions but also the need for a large amount of water storage - the Promax Corrugated big tanks are a perfect solution to this problem.


Promax Underground tanks are vehicular traffic approved - tested to AS/NZS 2566:1-1988 with a load rating of 28kpa. 

Click here to learn how to purchase Promax product online.