Building or installing a granny flat in Queensland?

Statewide Wastewater
Aug 12, 2025
3 min read

Whether you're planning a modular home, a secondary dwelling, or a self-contained unit on acreage – this is the must-read guide for wastewater and septic system compliance, costs, installation, and council rules.

From council approval and installing we break down everything you need to know to get your granny flat up and running fast.

Do Granny Flats Need a Septic System or HSTP?

Yes – if your property is not connected to town sewer, you are legally required to install a compliant onsite wastewater system for your granny flat.

This applies to:

Modular granny flats on rural or acreage land
Tiny homes or relocatable dwellings
Self-contained second dwellings with bathrooms and kitchens
Airbnb granny flats or rental units

You need wastewater if the granny flat includes:

A toilet
Shower or bath
Kitchen or laundry sink

Council will not issue final approval without a working wastewater treatment system.

Council Approval Process in Queensland

Every council in QLD requires approval before installing a wastewater system for a granny flat.

We manage the process for you, including:

Site & soil tests
Wastewater design plans
Application forms
Supply & Install
Plumbing compliance & final sign-off

Areas in:

Scenic Rim
Moreton Bay
Brisbane
Somerset
Lockyer Valley
Sunshine Coast Hinterland
Toowoomba
South Burnett
And Beyond

Done for you. Stress-free. No delays. One point of contact.

How We Help Modular Home & Granny Flat Builders

We work with:

Granny flat companies
Modular home installers
Owner-builders
Site managers

And provide:

Site-ready wastewater designs
Trade pricing
Fast compliance sign-offs
All drainage and plumbing included

Need multiple installs across SEQ? We can coordinate it all.

Areas We Service for Granny Flats, Modula Home etc.

We cover rural, hinterland, and fast-growing areas where granny flats are in demand:

Scenic Rim
Moreton Bay
Brisbane
Somerset
Lockyer Valley
Sunshine Coast Hinterland
South Burnett
Gympie
Toowoomba
Tamborine / Maleny
And Beyond

FAQs

Q: Can I put a granny flat on a septic system in QLD?

A: Yes, if approved by your local council. Soil type and lot size matter.

Q: Do I need a separate wastewater system for the granny flat?

A: Often yes – unless the main house system is large enough and up to code.

Q: What is the best septic system for a granny flat?

A: Brands like Taylex, Ozzi Kleen, Fuji Clean, Aqua Nova, BioCycle etc, HSTPs are recommended due to their size, quality and compliance. But we tailor the best suited system to your site and needs.

Q: How much space do I need for a septic system?

A: There are specific requirements for septic / HSTP system placements thats where we come in with a wastewater design.

Q: How long does installation take?

A: Each site is different and depends on approvals etc. We aim to complete jobs quickly to match your granny flat, modula build.

Why Choose Statewide Wastewater?

Trusted by granny flat & modular builders across QLD
Fast council approvals
Full install with plumbing, drainage & gas if needed
Fully Licensed & Insured
Ongoing servicing available

We take care of the entire wastewater side of your granny flat project.

Get Started Today

📞 Call us or request a quote to get your wastewater system approved and installed – fast, compliant, and stress-free. Call - 0406 288 142 Online Form - HERE