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.
Principles of intelligent urbanism
There is an appropriate balance to be found somewhere on the line between wasteful low-density individual systems and over-capitalized mega systems. Individual septic tanks and water bores servicing individual households in low-density fragmented layouts, allow the use of filtered greywater for free irrigation of gardens, but, if not maintained, can cause a local pollution of subterranean aquifer systems. The bores can dramatically lower ground water levels especially during droughts. The vantage of septic tanks an bores is to be managed by the very users, at no cost for the community.
Alternatively, large-scale, citywide sewerage systems and regional water supply systems are capital intensive and prone to management and maintenance dysfunction, if not corruption or extortion by private companies. Operating costs, user fees and cost recovery expenses are high. There is a balance wherein medium-scale systems, covering compact communities, utilize modern technology, without the pitfalls of large-scale infrastructure systems. This principle of urbanism promotes the middle path with regard to public infrastructure, facilities, services and amenities.