Septic tank
While a properly maintained and located septic tank does not pose any more environmental problems than centralized municipal sewage treatment, certain problems can arise with septic tanks in unsuitable locations. Since septic systems require large drainfields, they are not suitable for densely built areas.
Septic tank
In many council districts (e.g. Sunshine Coast) septic systems have been banned and need to be replaced with much more expensive small scale sewage treatment systems that actively pump air into the tank producing an aerobic environment. Septic systems need to be replaced with any new building applications, regardless of how well the old system performed.