What is the minimum amount of water required for a presoak during a perc test?

The minimum amount of water required for a presoak during a percolation test is 12 inches. This practice ensures that the soil is adequately saturated, allowing for an accurate assessment of its ability to absorb water. During the presoak, water infiltrates the soil, enabling the percolation rate to be measured effectively. By utilizing a depth of 12 inches, testing reflects conditions that are realistic for the soil's ability to handle effluent from a septic system. This depth is consistent with guidelines established to simulate the seasonal high groundwater level, which is vital for determining the suitability of soil for septic systems. Properly conducting the presoak is crucial, as insufficient soaking can lead to misleading perc rates and an inadequate understanding of the soil's behavior when it encounters wastewater.