The 7 main causes of failure

1. The on-site system (including the disposal field) not being designed and/or installed correctly, including inadequate site investigations, a lack of appropriate technical knowledge of systems by installers, and lack of innovation in developing systems applicable to a wide range of environments.

2. The system not being operated in accordance with the manufacturer’s guidelines.

3. The property owner (or occupier) not managing what goes into their system, or making sure the system receives regular servicing and maintenance as and when required. The report pointed out this is often because a property owner doesn’t know how to do it.

4. A system reaching the end of its effective life span and needing replacing, which could be identified early if a system was regularly managed and maintained, potentially saving a lot of money for a property owner.

5. The owner or other unqualified people undertaking repairs that were not in compliance with current standards.

6. Inadequate lids, vents, mushrooms and gully traps, some due to poor or old materials and/or construction, some to root intrusion.

7. A specific problem identified by Environment Southland was having disposal fields in close proximity (or over) tile drains, creating direct flow paths to ground and surface water.