The septic tank and any part of the leaching area, excluding approved tight-joint pipes, must be at least:
25' from house foundation wall. (If there are no footing drains - no drainage around the foundation to keep the basement dry (which generally applies only to a crawl space) - the setback is 15', and recently, may be reduced to 10' for a tank or pump chamber setback.
5' from a deck or shed when the structure is built on piers (like"sonotubes"), or 10' if the "accessory structure" is built on a foundation wall, unless it has footing or groundwater drains (making it 25').
25' from a curtain drain or other groundwater drain that is upslope of the system. (Fifty feet if downslope of the system) The same 25' setback applies to solid pipes carrying surface or ground water unless they are "tight pipe", such as SDR 35 or Sch 40 with joints of compression gaskets or 2-step solvent glue process, in which case the setback is 5 ft..
10' to "top of embankment", meaning, for example, that if you drew a level line from the top of your most downhill leaching structure the line should not emerge from underground till it was at least 10' from the edge of that structure.
10' from the property line; increase to 15' for elevated systems.
10' from a water line (potable water or irrigation lines under pressure)
75' from a well with a withdrawal rate of less than 10 gallons per minute (doubled - 150' - in very fast draining soils where there's ledge within 8' of system bottom and also if the well withdrawal rate is 10 to 50 gallons per minute)
50' from an open watercourse (streams, ponds, etc.) This is also the setback locally from a wetlands the "regulated area" extends greater than fifty feet in many towns. boundary, and
25' from an in-gound pool.
10' from an above-gound pool.
5' from a utility service trench (underground electric, gas, phone, etc.) but you are not allowed to backfill the trench with "free draining material" if within 25' of the system.