What You Should Know About Septic Inspections in NM

Homeowners are often surprised to find that their septic system doesn't pass inspection.  In their mind everything works great!  The problem is the difference in the definition of "working" between homeowners and the State regulators.  Most homeowners think that if everything "goes away" when the toilet is flushed, everything is working fine.  The State doesn't consider it working unless the waste is being treated before entering the ground.  Septic systems are not "disposal" systems, but rather "treatment" systems that rely on living organisms to clean and disinfect waste before letting it back out into the environment.  See the septic system page for further info on how a septic tank treats waste.

Specific requirements for a conventional septic system: 

_{This is not a complete list of requirements, but provides information on typical issues.}

1. The primary treatment area (tank) must be water tight.  This includes every portion of the tank and the connections between the inlet and outlet pipes.  A crack in the top of the tank will cause the tank to fail if it allows liquid in or out of the tank.  If the tank will not hold a vacuum, it is not water tight. 

2. The tank must have baffles to prevent churning and allow proper treatment times in the tank before the effluent is discharged.  Systems installed after September 1 of 2005  must also have an effluent filter installed and risers that extend the manholes to ground surface.

3.  The secondary treatment area (leach field) must accept effluent without creating saturated flow into the soil.  This means that the water flows only along the surface of the soil particles, but does not fill in the voids between soil particles.  The air in those voids is necessary for treatment of the effluent.  For this same reason it is important that the leach fields not be too deep.  Since there is no oxygen below 6' underground, the waste cannot be treated beyond this depth.  The state does not allow installations deeper than 6' to the bottom of the excavation for the leach field.  Also if the leach field is saturated it will not pass inspection.  If the leach field is saturated, the best remedy is to install another leach field while leaving the failed leach field in place.  Both leach fields should be connected to a distribution box so that they can be alternated (use only one of the leach fields at a time).  The reason for this is that most leach fields fail because the organisms that feed off of the effluent become overfed.  These fat and lazy organisms plug the bottom of the trench, preventing water from getting out.  If you put the organisms on a diet for about a year by not using their trench, they will slim down and go back to work.  Once there are two leach fields installed you should never have trouble again because you can always use one while the other one diets.  This overfeeding is caused by not pumping the tank often enough, so if the tank is neglected it is possible to have problems with both leach fields at the same time, but you would not let your tank go too long before pumping would you?