Adelaide Hills Council: the facts that change a job
Seven CWMS townships
Council is wholly responsible for community wastewater systems serving about 1,850 properties in Birdwood, Mount Torrens, Kersbrook, Charleston, Verdun, Woodside and Stirling (Golf Links Road).
Everyone else: on-site
Council's information sheet says sewer in the district is limited, and properties outside the CWMS townships have, or need, on-site wastewater systems.
Adelaide's water catchment
The council region is the primary catchment for Adelaide's water supply, so a wastewater system must be approved before planning consent is granted.
Houses, owned
At the 2021 Census, 95.9% of occupied homes in the council area were separate houses. 40.6% were owned outright and just 10.6% rented.
How the Hills CWMS works
The networks combine gravity drains, pumping stations and pressure mains. Birdwood has its own treatment plant, Kersbrook a lagoon, and Stirling, Woodside and Verdun discharge into SA Water's system. Council's 2025-26 Rating Policy says CWMS properties pay a service charge that covers running, maintaining and replacing the infrastructure.
On the CWMS, Council's sheet says a new house with a CWMS connection point needs a septic tank plumbed into it, so the tank stays part of your system. Our septic systems page explains how a plumber checks one.
Extending a house with an on-site system
Council's information sheet sets out a simple test. Minor alterations, where the existing system is working well, only need an application for the changes to the drains. Additions that let more people live in the house, a new spa bath, or a system that's already failing mean the waste control system must be upgraded.
The sheet dates back many years, so confirm the current requirements with Council's environmental health team before you design the renovation.
Buying in the Hills? Ask these first
- Is the house on mains sewer, the CWMS or its own on-site system?
- When was the system last serviced or pumped out, and are there records?
- Has Council approved any changes made to the drains or the system?
- Are exposed water pipes and tank lines lagged against frost?
Frost in the higher Hills
The Bureau's Mount Lofty station, at 685 m, averages 4.6 days a year at or below 2°C, with a July mean minimum of 5.0°C. Exposed pipes, tank pump lines and outside taps are the ones to lag before winter. A split pipe is a job for burst pipes in Adelaide.
Nearby Hills pages
Stirling has its own page, and so does Mount Barker, which is a different council. For water heaters, see hot water in Adelaide and heat pumps.
What we would do
Find out which of the three systems your property uses before you plan any work: mains sewer, the CWMS or on-site. That decides who approves the plumbing and what a plumber needs to bring. If you're adding a bedroom or a spa, talk to Council's environmental health officers early, because an upgrade can be a condition of approval. Then let us find you a specialist in Hills wastewater.