What must all pretreatment units and distribution boxes have?

All pretreatment units and distribution boxes are required to have KY approval numbers. This requirement ensures that these systems meet state regulations and standards for performance and safety before they are installed. Having an approval number indicates that the unit has been tested and certified by the appropriate regulatory authority, which is crucial for ensuring that the system will function properly in its intended environment. This adds a layer of assurance for both installers and property owners that the septic system components conform to applicable laws and guidelines, thus promoting public health and environmental protection.

In contrast, while having installation instructions, maintenance logs, and manufacturer's warranty certificates may be beneficial for operational and legal reasons, they are not mandated for all pretreatment units and distribution boxes in the same way that approval numbers are. Therefore, the critical aspect highlighted in the question pertains specifically to the necessity of regulatory approval.