Drainfield Size Calculator Guide

The Drainfield Size Calculator determines the required leach field area based on daily wastewater flow and soil percolation rate.

How to use it:

Enter the daily wastewater flow in gallons per day (GPD)

Enter the soil percolation rate from a perc test (minutes per inch)

Select the system type (conventional gravity, pressure distribution, etc.)

Click Calculate for the recommended drainfield area

Soil percolation rates and what they mean:

1-10 min/in: Sandy soil — smaller drainfield needed, but may require pretreatment

10-30 min/in: Loam — ideal range for conventional systems

30-60 min/in: Clay loam — larger area required, may need pressure distribution

Over 60 min/in: Heavy clay — usually unsuitable for conventional drainfields

Always verify drainfield sizing with a professional engineer and your local permitting authority.