GWMWater

Wastewater is different to stormwater

Understanding the difference helps protect your home, your community and our waterways.

Wastewater

Wastewater is used water from inside your home, including:

  • Toilets

  • Showers and baths

  • Sinks and washing machines

This water flows through the sewerage network to a treatment plant, where it’s cleaned before being safely released.

Stormwater

Stormwater is rainwater that falls on:

  • Roofs

  • Driveways

  • Paths

  • Lawns and gardens

Stormwater should flow into the stormwater system, which carries it directly into creeks and rivers without treatment.

Why stormwater must not enter the sewerage system

The sewerage system is designed for wastewater only.

When rainwater enters the sewer system:

  • Pipes can become overloaded during wet weather.

  • Sewage may overflow into streets, parks and private properties.

  • Waterways can be polluted.

  • Treatment and pumping costs increase for everyone.

That’s why connecting stormwater to the sewerage system is not allowed.

What we’re doing

We work to reduce stormwater entering the sewerage system by:

  • Investigating areas with wet‑weather overflows.

  • Using smoke testing (sewer fogging), dye testing and CCTV inspections to find incorrect connections.

  • Working directly with property owners when issues are found.

If an illegal or incorrect stormwater connection is identified on private property, we’ll explain what needs to be fixed and follow up in writing if required.

What you can do to help

Check your overflow relief gully (gully trap)

An overflow relief gully is a small drain outside your home that allows sewage to escape safely if pipes become blocked, helping prevent sewage backing up inside.

To make sure it works properly:

  • Ensure the ground around the gully slopes away from your house.

  • Make sure it sits at least 75 mm above ground level.

  • If the gully is too low, rainwater can enter the sewer.

  • If it’s too high, sewage could back up inside your home.

If you’re unsure, contact a licensed plumber for advice.

Maintain your property’s sewer pipes

You can help prevent problems by:

  • Keeping maintenance holes clear and uncovered.

  • Avoiding planting trees over sewer pipes.

  • Never connecting roof downpipes to sewer drains or gullies.

  • Directing downpipes at least one metre away from buildings.

  • Repairing broken water or sewer pipes promptly.

  • Checking internal drainage pipes are in good condition.

See a problem?

  • On your property: Contact a licensed plumber.

  • On public land or another property: Call 1800 188 586 any time and we’ll investigate.

Do our 5-minute audit

Walk around your property and tick these off. Anything you spot is worth a call to a licensed plumber to fix.

  • Roof downpipes

    Do they run into a stormwater drain — not a sewer pipe or gully?

  • Rainwater tank overflow

    Where does the overflow pipe go? It should not enter the sewer.

  • Yard and surface drains

    Confirm they discharge to stormwater, not sewer.

  • Roof water direction

    Water should flow at least 1 metre away from buildings.

  • Manhole and gully covers

    Look for cracks, missing covers or pooling water around them.

Need more information?

Whether you’re after more information or would like to discuss things further, please reach out to us.