Contact your county planning or health department and ask for a record drawing of your septic system. A formal plan of your septic layout was required to be filed and approved before construction. This drawing, if available, will show the locations of your septic system components. Measure the distance as shown on the diagram to locate your drain field. If this drawing is not available, proceed to step 2.
Examine grasses and other plants on your property. Plants that cover a drain field will receive larger amount of water than other areas of your property, and the effects should be visible. Look for areas that grow faster, turn green quicker in the spring, or stay green longer during droughts and in autumn.
Examine your property during periods of snow melt. Because of the heat present in waste water, the drain field will often show as an area where snow and ice melt quicker.
Examine the contour of your property. The drain field may have depressions, furrows, or other evidence of underground water flows. The drain field will typically be lower in elevation than the house and septic tank.
Call a septic professional as a last resort. Metal pipes can often be located with electronic detectors.