MID VALLEY SEPTICS
Septic Tank & Trench Systems: Design and Installation
The septic tank and absorption trench system is the traditional on-site solution for homes that aren’t connected to town sewer, and on the right property, it’s hard to beat. It’s simple, it’s often gravity-fed, and it usually costs less upfront than other options. The catch is that it only works where the site suits it. Mid Valley Septics designs and installs septic tank and trench systems across the Mid North Coast, and we start by checking whether your block can actually support one.
25+ years experience
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Septic Tank Trench Systems
How a Septic Tank and Trench System Works
Wastewater flows from the house into the septic tank. Inside, solids settle to the bottom as sludge, fats and oils float to the top as scum, and bacteria begin breaking the waste down. The clarified liquid, called effluent, flows out through an outlet filter and into the absorption trenches, which are shallow trenches that spread the effluent into the soil. The soil does the final treatment, filtering and breaking down what remains before it reaches groundwater.
Is a Tank and Trench System Right for Your Property?
- The block is large enough for the trenches, the required buffer distances and, where council asks for one, a reserve area
- The soil absorbs effluent at a suitable rate, neither too tight (heavy clay) nor too open
- Groundwater sits well below the trenches
- The land isn't steep or flood-affected
- The site is well clear of creeks, dams and bores
It’s usually not the right choice on small lots, in heavy clay, where the water table is high or the land floods, or in sensitive environments. In those cases we’ll look at alternatives such as an aerated wastewater treatment system or a sand filter system, and explain why.
IS IT RIGHT FOR YOU?
Tank and Trench vs Other Systems
Septic tank and trench: lower upfront cost, simple, often no electricity needed. Needs space and well-draining soil, and regular pump outs.
AWTS: higher level of treatment and a smaller footprint, suits difficult sites. Higher upfront cost, needs power and quarterly servicing.
Sand filter: suits poor soils. Needs space for the filter bed.
What's Involved in Installing a Septic Tank and Trench
- Site and soil assessment to confirm the trench area and any reserve area
- Design of the tank size and trench layout for your household
- Council approval, including the Section 68 application
- Excavation and installation of the tank, pipework and absorption trenches
- Council inspections at the required stages
- Reinstatement of the area, commissioning and handover documentation
Our in-house team handles each step, from the first site visit to the final handover.
Why Choose Mid Valley Septics
- Septics and wastewater is all we do, not a side job for a plumber
- Design, installation and servicing all done in-house, with nothing subcontracted
- 25+ years of experience across the Mid North Coast
- Honest advice, including telling you when a tank and trench isn't the right system
Looking After a Tank and Trench System
A tank and trench system will serve a property well if it’s looked after:
Have the tank pumped out about every three to five years
Keep vehicles, livestock and heavy loads off the trenches
Keep tree roots away from the trench area
Spread laundry across the week and fix leaking taps and toilets
Keep fats, wipes and harsh chemicals out of the drains
Have systems over 15 years old inspected annually
Service Areas
Council Approval Across the Mid North Coast
Where your property is decides who assesses your design. We prepare designs for properties across Coffs Harbour City Council, Nambucca Valley Council, Kempsey Shire Council, Port Macquarie-Hastings Council and MidCoast Council areas, and we’re familiar with how each handles on-site sewage applications. Installing or altering a system needs Section 68 approval, and operating one needs an approval to operate. A design prepared with your council’s requirements in mind avoids rounds of requests for more information.
Coffs Harbour
Kempsey
Taree
QUESTIONS
Frequently Asked Questions
Get clear, reliable answers from the experts.
Do I need council approval for a septic tank and trench system?
Yes. Installing a system needs approval under Section 68 of the Local Government Act 1993, and operating it requires approval to operate. We manage the application.
How much land do I need for absorption trenches?
It depends on your soil, the number of bedrooms and your council’s buffer requirements. A site and soil assessment gives you a definite answer for your block.
Can I put a septic tank and trench on a small block?
Usually not. Small lots rarely have room for the trenches and buffers. An AWTS is the more common choice.
How often does a septic tank need pumping out?
Most residential tanks need pumping about every three to five years, depending on household size and use.
How long will a tank and trench system last?
With the right design and regular maintenance, a system can serve a property for many years. Soil, household size and how well it’s maintained all affect that.
Is a septic tank and trench better than an AWTS?
It’s simpler and cheaper upfront, but it needs a big, well-draining site. An AWTS suits harder sites but needs power and quarterly servicing.
MID VALLEY SEPTICS
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