Kentucky Registered Environmental Health Specialist (REHS) Practice Test 2025 - Free REHS Practice Questions and Study Guide

Increasing the capacity of a septic tank to accommodate a garbage disposal unit is based on the additional waste load that this type of appliance introduces into the system. When a garbage disposal is used, it contributes organic waste, which requires more treatment and processing than typical household wastewater.

The recommendation of a 50 percent increase in septic tank capacity is grounded in the need to ensure that the tank can effectively manage the additional solid waste. This adjustment helps prevent issues such as tank overflows, reduced separation efficiency, and increased strain on the entire septic system. An adequately sized tank is crucial for maintaining system performance, ensuring solids are properly retained, and allowing sufficient time for the anaerobic digestion of waste material.

When a garbage disposal is in use, it not only increases the volume of effluent but also potentially alters the composition of the waste, as more food particles can lead to more solids that need to be settled and decomposed. Therefore, doubling the capacity may be excessive and inefficient, while a 25 percent increase might not sufficiently accommodate the extra load. A 50 percent increase strikes a balance, providing enough capacity to handle the added waste without overburdening the septic system.