Septic System Engineering
Properties not connected to mains sewerage require an on-site wastewater management system. Septic systems must be properly designed to handle the wastewater volumes generated by the household, treat effluent to the required standard, and dispose of it safely without impacting groundwater, waterways, or neighbouring properties.
Our engineering team provides comprehensive septic system design services — from initial site and soil assessment through to detailed engineering drawings for council approval. We design systems that meet all regulatory requirements while being practical and cost-effective for your site.
System Types
Conventional Septic
Traditional two-chamber tank with absorption trench disposal. Suitable for larger blocks with appropriate soil permeability. The most common and cost-effective on-site system.
Aerated Treatment
Mechanically aerated system producing higher quality effluent. Suitable for smaller lots and more sensitive environments. Requires ongoing maintenance and power supply.
Sand Filter
Secondary treatment through engineered sand media. Produces high-quality effluent suitable for sub-surface irrigation. Ideal where soil conditions limit conventional absorption.
Constructed Wetland
Natural treatment system using aquatic plants and gravel beds. Environmentally sensitive solution for rural properties. Requires larger land area but minimal ongoing energy use.
Sizing & Site Assessment
Correct sizing of the septic system is critical to ensure effective treatment and disposal of wastewater. The design must account for the number of occupants, daily water usage, soil permeability, site slope, and setback requirements from boundaries, waterways, and bores.
Tank Sizing Factors
- Number of bedrooms (equivalent persons)
- Daily wastewater generation estimates
- Retention time for adequate treatment
- Sludge accumulation and pump-out intervals
Site Assessment
- Soil percolation testing (permeability rates)
- Groundwater depth and seasonal variation
- Site slope, aspect, and vegetation cover
- Setback distances from buildings, boundaries, and waterways
Council Approval Process
All on-site sewage management systems require approval from your local council before installation. The approval process involves submitting detailed engineering designs, site assessments, and environmental impact considerations. Our team prepares all documentation required for a smooth approval process.
- Section 68 application preparation (Local Government Act 1993)
- Detailed engineering drawings showing system layout, setbacks, and disposal area
- Site and soil evaluation report per AS/NZS 1547
- Environmental impact assessment for sensitive locations
- Ongoing operation and maintenance plan documentation
Need septic system design?
From septic tanks to treatment systems, our team delivers compliant, environmentally responsible solutions.