Stormwater Tanks 101

When a heavy Australian downpour hits, your property needs to handle a massive volume of water in a very short amount of time. This is where Stormwater Tanks come into play.

Unlike a standard storage tank, a stormwater system is an engineered solution designed to satisfy local council requirements and protect your property from flooding. At Polymaster, we specialise in Retention and Detention systems that provide “Measurement Honesty” and certified structural integrity.

Retention vs. Detention: What’s the Difference?

Understanding the terminology is the first step in choosing the right stormwater tank. While they look similar from the outside, their internal plumbing serves two very different purposes.

The Comparison Table

1. Retention Systems (Sustainable Storage)

These tanks are designed to keep the water “retained” for your own use. By harvesting stormwater, you take the pressure off the mains supply.

• Best for: Watering gardens, washing cars, and flushing toilets.

• Polymaster Value: Our food-grade, BPA-free poly ensures the water stays clean and safe for all household applications.

2. Detention Systems (Flood Mitigation)

A detention tank is designed to remain empty (or partially empty). During a storm, it captures the “peak” surge of water from your roof and slowly releases it into the council drains through a small orifice.

• Best for: Meeting council “Permissible Site Discharge” (PSD) requirements.

• Polymaster Value: We factory-drill the orifice outlets to your exact engineer’s specifications, ensuring you pass your final council inspection without a hitch.

3. Dual-Use (Retention & Detention Combo)

The most popular modern solution is a Dual-Use Tank. One single tank acts as both a storage unit (the bottom half stays full for your garden) and a flood-mitigation tool (the top half stays empty to catch storm surges).

Why Stormwater Flow Control Matters

Without a stormwater tank, a heavy rain event causes a “Peak Flow” spike. This is what leads to burst pipes, eroded landscapes, and flash flooding in our suburbs.

As shown in the graph above, a detention tank “flattens the curve” of the water discharge, protecting your property and the broader community infrastructure.

The Polymaster Promise: Engineering You Can Trust

When you invest in a Stormwater Tank, you are investing in the structural safety of your home. A poorly built tank can buckle under the rapid pressure changes of a storm.

Why choose Polymaster for Stormwater?

• Measurement Honesty: We provide the exact air-gap and usable volume measurements required by your hydraulic engineer.

• Factory Fitting: We fit all overflows, orifice outlets, and valves in the factory. This reduces stormwater tank installation costs because your plumber doesn’t have to spend hours on-site drilling and sealing.

• Certified Quality: Every tank is independently certified to AS/NZS 4766, ensuring it can handle the weight of the water and the heat of the sun for decades.

• Aesthetic Range: Available in a wide variety of colours to match your home’s colorbond roof or fencing.

Summary: Getting Your Council Approval

Most new builds in Australia now require a registered stormwater management plan. Don’t leave it to the last minute—a custom-fitted Stormwater Tank from Polymaster ensures you meet your legal obligations while gaining a valuable asset for your property.

Ready to specify your tank? Explore the Polymaster Stormwater Range and download our technical spec sheets today.