Installing on-site sewerage facilities

On-site sewerage facilities treat domestic sewage in unsewered areas. The facility can treat, store and dispose of sewage generated on the premises. A facility may include either:

• an on-site sewage treatment plant, which uses mechanical, biological and filtration methods to treat waste before discharging through either above- or below-ground irrigation systems
• a septic system, which uses biological methods to treat waste before discharging through a below-ground system
• dry-vault toilets that are chemical, composting or incinerating toilets.

Approvals for on-site sewerage facilities

Installing an on-site sewage treatment plant requires:

• local government approval
• treatment plant approval in accordance with the Plumbing and Drainage Act 2018. A septic system does not require treatment plant approval.

If homeowners don't have approval, the system can't be installed in Queensland.

Check the Queensland Plumbing and Wastewater Code (PDF, 1.1MB) and Australian Standard AS1546.3:2017 for details on the performance requirements and criteria used to assess on-site sewage treatment and greywater treatment facilities.

Who issues approvals?

The Department of Housing and Public Works issues chief executive approvals for on-site sewage treatment plants to treat sewage from fewer than 21 equivalent persons.

The Department of Environment and Science issues approval for systems treating sewage from 21 equivalent persons or more.

Composting toilets

Composting toilets use a process of biological degradation to convert nightsoil into a humus-like substance through the aerobic action of micro-organisms and invertebrates.

New composting toilet installations presented for sale in Queensland must comply with Part F1.4 Composting, chemical and incinerating toilets of the Queensland Plumbing and Wastewater Code (PDF, 1MB).

Consumers who purchase a composting toilet must request a written statement of compliance from the manufacturer or distributor. Submit this statement to the local government with the approval application. We won't accept composting toilets previously approved by Queensland Health or the Environmental Protection Agency as evidence of compliance.

Pre-approved systems

The Department of Housing and Public Works has already approved wastewater treatment systems for varying qualities of effluent. Find out more about these qualities and their approved systems below:

• secondary
• advanced secondary
• advanced secondary with nutrient removal.

Secondary quality

Compliance characteristics of secondary quality effluent:

• 90% of the samples taken over the test period have a BOD5 less than or equal to 20g/m³, with no sample greater than 30g/m³.
• 90% of the samples taken over the test period have total suspended solids less than or equal to 30g/m³, with no sample greater than 45g/m³.
• Where disinfection is provided, 90% of the samples taken over the test period have thermotolerant coliform count not exceeding 200 organisms per 100ml, with no sample exceeding 1,000 organisms per 100ml.
• Where chlorination is the disinfection process, the total chlorine concentration is greater than or equal to 0.5g/m³ and less than 2.0g/m³ in 4 out of 5 samples taken.

Approved facilities

Advanced secondary

Compliance characteristics of advanced secondary quality effluent:

• 90% of the samples taken over the test period have a BOD5 less than or equal to 10g/m³ with no sample greater than 20g/m³ .
• 90% of the samples taken over the test period have total suspended solids less than or equal to 10g/m³ with no sample greater than 20g/m³ .
• Where disinfection is provided, 90% of the samples taken over the test period have thermotolerant coliform count not exceeding 10 organisms per 100ml with no sample exceeding 200 organisms per 100ml.
• Where chlorination is the disinfection process, the total chlorine concentration is greater than or equal to 0.5g/m³ and less than 2.0g/m³ in 4 out of 5 samples taken.

Approved facilities

Advanced secondary with nutrient removal

Compliance characteristics of advanced secondary quality effluent with nutrient removal:

• 90% of samples taken over the test period have a BOD5 less than or equal to 10g/m³ with no sample greater than 20g/m³ .
• 90% of samples taken over the test period have total suspended solids less than or equal to 10g/m³ with no sample greater than 20g/m³ .
• Where disinfection is provided, 90% of the samples taken over the test period shall have a thermotolerant coliform count (not exceeding 10 organisms per 100ml with no sample exceeding 200 organisms per 100ml.
• Where chlorination is the disinfection process, the total chlorine concentration is greater than or equal to 0.5g/m³ and less than 2.0g/m³ in 4 out of 5 samples taken.
• 90% of the samples, with 95% confidence limits, taken over the test period have a total nitrogen concentration less than or equal to 10mg/l.
• 90% of the samples, with 95% confidence limits, taken over the test period have a total phosphorus concentration less than or equal to 5mg/l.

Approved facilities