There are times, even with new systems, when the problem causing a whole — house backup is in the septic tank. These occasions are rare, but they do exist. When this is the case, the top of the septic tank must be uncovered. Some tanks, like the one at my house, are only a few inches beneath the surface. Other tanks can be buried several feet below the finished grade.
Once a septic tank is in full operation, it works on a balance basis. The inlet opening of a septic tank is slightly higher than the outlet opening. When water enters a working septic tank, an equal amount of effluent leaves the
tank. This maintains the needed balance. But, if the outlet opening is blocked by an obstruction, water can’t get out. This will cause a backup.
Strange things sometimes happen on construction sites, so don’t rule out any possibilities. It may not seem logical that a relatively new septic tank could be full or clogged, but don’t bet on it. I can give you all kinds of things to think about. Suppose a septic installer was using up old scraps of pipe for drops and short pieces, and one of the pieces had a plastic test cap glued into the end of it that was not noticed? This could certainly render the septic system inoperative once the liquid rose to a point where it would be attempting to enter the outlet drain. Could this really happen? I’ve seen the same type of situation happen with interior plumbing, so it could happen with the piping at a septic tank.
What else could block the outlet of a new septic tank? Maybe a piece of scrap wood found its way into the septic tank during construction and is now blocking the outlet. If the wood floated in the tank and became aligned with the outlet drop, pressure could hold it in place and create a blockage. The point is that almost anything could be happening in the outlet opening, so take a snake and see if it is clear.
If the outlet opening is free of obstructions, and all drainage to the septic tank has been ruled out as a potential problem, you must look further down the line. Expose the distribution box and check it. Run a snake from the tank to the box. If it comes through without a hitch, the problem is somewhere in the leach field. In many cases, a leach field problem will cause the distribution box to flood. so, if you have liquid come rushing of the distribution box, you should be alerted to a probable field problem.
