If you’re planning wastewater for a genuinely off-grid property, a composting toilet paired with a separate greywater system is a real alternative to a standard septic or AWTS setup — not just a fringe option. It’s worth understanding how the two approaches actually compare before you commit, because they solve the same underlying problem in very different ways.
How They Differ
A septic or AWTS system treats all of your household wastewater– toilet (blackwater) and sink/shower/laundry (greywater), together, through one system, before dispersing it on-site. A composting toilet removes blackwater from the equation almost entirely: waste is broken down aerobically in a dedicated composting chamber rather than being flushed and treated as wastewater. Many modern composting toilets are urine-diverting — separating liquid waste from solids at the source — which speeds up composting, cuts odour significantly, and is one of the main reasons composting toilets have moved well beyond their old reputation. Greywater from the rest of the house still needs its own treatment and disposal system, just a much smaller one than if it were handling blackwater too.
Where a Composting Toilet Makes Sense
- Very constrained sites where even a compact AWTS disposal area is difficult to fit
- Properties with genuinely poor soil where any form of effluent disposal is a challenge
- Owners specifically prioritising an eco-friendly, water-conserving setup, since most composting and urine-diverting toilets use little to no water
- Cabins, sheds or secondary dwellings where a full septic system would be disproportionate to the level of use
Where a Standard Septic or AWTS Still Makes More Sense
- Full-time family homes where household buy-in to composting toilet upkeep (turning/managing the compost, emptying it) is a genuine consideration
- Properties being sold in the near-to-medium term, septic and AWTS systems are far more familiar to buyers and valuers than composting toilet setups
- Sites with reasonable soil and space, where a standard system is simpler and requires less hands-on management
Maintenance: What’s Actually Involved
A composting toilet needs regular attention from the household, adding bulking material, periodically turning or rotating the compost, and emptying the finished compost material, typically every few months depending on the unit and usage. Urine-diverting models also need the liquid container emptied more frequently, though this is a quick job. A septic or AWTS system needs far less day-to-day input from the household, but requires periodic professional servicing and pump-outs instead. It’s a trade-off between more frequent, hands-on but low-cost household maintenance versus less frequent but professional (and paid) servicing.
What About Council Approval?
Composting toilets still fall under NSW on-site sewage management requirements, and the greywater system that runs alongside one needs its own Section 68 approval, the same as it would with a standard system. Composting toilet approval can vary more between councils than septic approval does, since it’s a less common system — worth confirming your specific council’s position early rather than assuming it’s a given.
Which Should You Choose?
For most off-grid properties, a well-designed septic or AWTS system remains the simpler, lower-maintenance-from-the-household’s-perspective option, and it’s what most councils, buyers and lenders are set up to deal with. A composting toilet, particularly a modern, urine-diverting design, is a genuine option worth considering specifically where site constraints are severe, eco-friendly water conservation is a real priority, or the property’s use pattern (a cabin, a shed conversion) doesn’t justify a full system. The right call comes down to your specific site and how the property will actually be used.
FAQ
Do I still need a septic system if I install a composting toilet?
You’ll still need a system for greywater (sinks, shower, laundry) — a composting toilet only removes blackwater from the equation, not household wastewater generally.
Is a composting toilet cheaper than a septic system?
Upfront costs can be lower for the toilet itself, but you still need a compliant greywater system alongside it, and ongoing household maintenance (turning, emptying) replaces professional servicing rather than eliminating maintenance altogether.
Do councils approve composting toilets in NSW?
Generally yes, alongside a compliant greywater system, but approval requirements can vary more by council than standard septic approval does, worth confirming with your specific council early.