First install the tile disposal field where there will be least danger
of polluting water supplies, at least 100 feet from water sources if
possible and always at a lower surface elevation. This is of greatest
importance. Even though selecting a more distant location would result
in greater initial cost, it would be a good investment as protection
against diseases that might result from pollution of water sources.
The site should slope away from the house and away from the source of
water. Gentle unshaded slopes free of trees or shrubbery are best.
Root-free locations are important because the open-jointed tile cannot
be "rootproofed." Porous, well-drained, gravelly, or sandy soil allows
greater purification. Do not have the disposal field in vegetable
gardens, under roadways, in swampy land, in muck soils, or in areas
having rock substrata sloping toward the water supply. Allow sufficient
area, where available, to enlarge the field later if needed.
The septic tank may be close to the house, but a more distant site
would reduce the likelihood of odors if leakage occurs. The tank should
also be kept 50 feet or more from any source of water supply and at a
lower elevation. It should not be placed under driveways, pavements, or
flower beds, as these would make it not readily accessible for periodic
inspection. Care should be taken to insure that surface drainage from
the area around the tank will not reach the vicinity of the water
supply.