FlushMax™ Brochure

Ausdrain’s FlushMax™ system is an innovative inspection, cleaning and maintenance system designed to provide permanent access to Ausdrain EnviroModule™2 modular tanks. The system offers designers, builders and property owners a cost-effective and practical solution to enable the long-term maintenance of EnviroModule™2 tanks.

FlushMax™ modules are supplied pre-assembled and are easy to install. The modules create continuous rows of 300mm perforated pipes that run in either single or multiple rows throughout the tank. The flow rate of the inlet pipe(s) can be matched to the number of FlushMax™ modules required. For pipe dimensions greater than 300mm a manifold system can be designed to match the inflow rate of larger inlet pipes.

Stormwater entering the inlet pit will first be filtered by a Gross Pollutant Trap (GPT) or maxi mesh screen attached over the inlet to the FlushMax™ row. In the event that silt or debris enters the FlushMax™ row, secondary filtration will occur as the first flush carries any suspended solids into the outlet pit where they can be easily removed.

Any solids that remain within the FlushMax™ row will settle on the base where they can be flushed out by a high pressure hose via the inspection pits at maintenance intervals.

In addition to the benefits of permanent tank access for maintenance, FlushMax™ also provides an efficient and even discharge of water throughout the Ausdrain tank and draw down of water to external pump systems for irrigation purposes.

Download our our FlushMax™ Product Brochure:

FlushMax™ Brochure
FlushMax Maintenance Module

FlushMax™ Technical Data



Maximum Load



Inlet Diameter




Outlet Diameter




Flow Rate


Compressive Strength

17.8 tonnes/m2

Manning Valve (k)




Reprolene (Recycled Polypropylene)





Installation Procedure for 300mm Drainage Cell

1. Refer to EnviroModule™2 installation guide for instructions on module assembly, installation and backfilling of each tank type.

2. Identify the row(s) of FlushMax™ on the plan and align the 600mm side of the FlushMax™ modules with the 600mm side of the adjacent EnviroModules™2. Note: For residential rainwater harvesting and onsite detention tanks the FlushMax™ row must be at the base of the tank. For infiltration tanks the FlushMax™ row must be at the top of the tank.

3. Place the pre-assembled FlushMax™ modules from end to end of the tank within the liner/geotextile layer and butt together.

4. Place all remaining EnviroModule™2 on either side of the FlushMax™ row(s). Note: for multiple rows of FlushMax™ ensure they are separated by at least one row of regular modules.

5. Connect a piece of 300mm PVC pipe to the inlet and outlet of the FlushMax™ row(s) for connection to the adjacent pit(s).

6. Install all remaining EnviroModule™2’s to complete the tank structure.

7. Cut an X in the geotextile and 300mm diameter hole in the liner where the inlet and outlet pipes are to allow them to fit through. Wrap the impermeable liner and/or geotextile completely around the tank allowing for the 300mm inlet/outlet pipes
to protrude.

8. Secure the geotextile with duct tape around the pipes and clamp using an adjustable band clamp. If using an impermeable liner, fit the self-adhesive pipe boot over the inlet and outlet pipes as per the instructions provided.

9. Connect the 300mm inlet/outlet pipes to each adjacent pit. A galvanised mesh screen should be bolted over the inlet pipe only. Backfill the tank as per the EnviroModule™2 Installation Guide.