What is the minimum time for a perc test hole to remain filled?

The minimum time for a perc test hole to remain filled is 15 minutes because this duration allows for an accurate assessment of the soil's permeability. During this waiting period, the water in the hole stabilizes, enabling observers to measure how quickly the water level drops. This information is crucial for determining the soil's ability to absorb water, which directly impacts the design and viability of onsite wastewater disposal systems. A shorter duration may not provide a clear understanding of the soil's properties, while a longer duration might not be necessary for an effective evaluation. Therefore, 15 minutes is considered the appropriate minimum time for effectively conducting a percolation test.