Your home uses a septic system and you need to perform maintenance on the piping. To do this you need access to the distribution box, but you have no idea where the box was installed. All you know is that somewhere under your lush green lawn lies a concrete box that you need to find. In some instances it won't take long to find the distribution box of a septic tank, but in others it is a study in frustration and perseverance.
Check for installation records. A record of your system may have been filed when the installer applied for a permit. If so, a diagram may have been included. The diagram will show you the location of the septic tank, the routing of the pipes, the field line locations and the location of the distribution box. Remember the diagram was the original plan and may not indicate the exact location of the distribution box, but it provides a good starting point to work from.
Locate the area where you believe the field lines to be located. This should be a large, level area free of trees or large shrubbery. In most cases any lawn or vegetation over the field lines will be lush and green. Look for a pattern in the grass that may indicate the exact locations of the field lines. The grass may appear darker, thicker or faster-growing in these areas. Follow this lines toward your home. If there is a common intersection point, this will be the location of your distribution box. Dig down to confirm the location. The distribution box will be buried from 2 to 4 feet below the surface.
Rent or borrow a metal detector if no plans are available and no pattern can be detected in the grass or vegetation. Once again go to the area where you believe the field lines to be located. Slowly scan the ground as you move toward the house. While the distribution box is made of concrete, there should be reinforcing metal re-bar built into the box that the metal detector will locate. Identify a pattern to your search so you do not inadvertently cover the same area multiple times.
Drive a metal rod or prybar into the ground in the area where you believe the distribution box is located. Consider this your "last ditch, nothing else has worked" effort. It is by far the most work with the worst odds of locating the distribution box. Drive the rod deep enough in the ground, 2 to 4 feet, to strike the distribution box. When you strike something, dig a small test hole to determine if it is the box or only a large rock. Keep track of where you have searched so you do not waste time going over the same area twice.