For Annex IV compliance, which statement is correct about type approval?

• A. Type approval is not required for any of the systems
• B. Only treatment plants require type approval
• C. Only holding tanks require type approval
• D. Any of the above, provided the system is type approved

Answer: (D)

For Annex IV compliance, the essential idea is that the system used must have undergone type approval. Type approval is a formal certification by the competent authority showing that a design or model meets defined performance and safety standards. Because Annex IV covers different types of components that can achieve the required treatment, any of those components—whether a treatment plant, a holding tank, or another suitable unit—can achieve compliance as long as that specific model has been type approved. If a system lacks this approved status, it cannot be considered Annex IV compliant, regardless of its category. So, the correct stance is that any of the above can be compliant, provided the system chosen is type approved.