Size a conventional gravity drainfield from percolation test results using a state code table

Steps

1. Obtain the percolation rate (minutes per inch) from a properly conducted perc test
2. Look up the required square footage per bedroom for that percolation rate in the state's onsite wastewater rules (e.g., Nebraska ties drainfield square footage to both bedroom count and perc rate under its Title 124 onsite wastewater rules)
3. Calculate total drainfield area needed by multiplying the per-bedroom square footage by the design bedroom count
4. Apply any required soil/site reduction or additional factors (slope, groundwater separation) called out in the state design standard
5. Lay out trenches or beds to meet the calculated area while respecting minimum setback distances