Department of Food, Agricultural and Biological Engineering

 


Articles Contributed to Ohio's Country Journal  
April  2003

 


FABE Homepage

Ohio's Country Journal

OCJ Articles 

 

 

 

 

 

January -  2004

Applied Engineering

Why septic systems malfunction  
Karen Mancl  

A contaminated well, untreated sewage discharging to a stream, or a soft smelly spot in the yard with lush grass growth - these are just some of the signs that a septic system has malfunctioned.

Not every sign of a malfunction is obvious. In improperly designed systems, untreated sewage can move for hundreds of feet from a home before contaminating the environment or threatening the public health. The offending property owner may not even know that a problem exists.

The purpose of a septic system is to remove pollutants from wastewater. Systems can be out of compliance for two major reasons. The system may be malfunctioning or it may be failing.

System malfunctions
A system malfunctions by definition can be fixed. With proper care, oversight, repairs and occasional upgrades the system should work for decades. Malfunctioning systems were initially properly designed and installed to match the soil and other conditions on the home lot.

The reasons for a malfunction may be:

  • A household water leak or excess water use that overloads the system.

  • Changes in landscaping that paves over, crushes or damages a portion of the system.

  • Changes in position of downspouts, rain gutters and paved areas that drain excess water into the area of the yard with the septic system.

  • Failure to pump the septic tank to remove excess sludge and scum.

Avoiding system malfunctions
For systems that are properly designed and constructed it is easy to avoid malfunctions. Four simple steps should be followed.

  1. Avoid excess water use. Using too much water is the single biggest reason for system malfunction. The soil under the septic system must absorb all of the water used in the home, therefore it is important to limit the amount of discharged water. It is also important to space out water use by staggering loads of laundry to one per day and timing showers throughout the day.

  2. Be careful when changing landscaping. The septic system is buried just beneath the ground surface and can be damaged if vehicles drive over or are parked on top of it. Paving over even a portion of the system can damage it leading to a malfunction. Most importantly, be careful not to direct excess rainwater to the area where the septic system is buried. Make sure downspouts and drainage off roofs and pave areas flow to other areas of the home lot.

  3. Install risers and inspection ports. Because the system is buried, it is difficult to inspect to check for problems leading to a malfunction. To facilitate quick and frequent inspection, small inspection ports should be installed at the end of each lateral line. By extending the inspection ports up to the ground surface they can be easily mowed over, while still providing easy access to check for ponding in a lateral, which is an early warning sign of malfunction. Risers over the lid of a septic tank make it easy to inspect and pump the septic tank.

  4. Regular professional inspection. Each year a quick inspection of the lateral lines reveals possible problems. If ponding is observed, first check for excess water use or changes in drainage of rainwater on the lot. Fixing a water leak or moving a downspout may correct the problem. If not, a portion of the field may have to be rested to restore its treatment capacity. Fortunately most counties require the construction of two lateral fields with a valve to switch them, which  makes resting easy at no additional cost. If this is not the case, additional lateral lines may need to be installed with a valve to allow for resting a portion of the system.

Septic tanks should be checked for damage every three years and pumped when needed. See AEX-740 Septic Tank Maintenance for recommended septic tank pumping frequency. This and other publications are available from local county Extension offices or at http://ohioline.osu.edu

System failures can't be fixed
A system failure by definition cannot be fixed to bring the system back into compliance. In these difficult situations, the existing system must be abandoned and a new system constructed. Unfortunately, many home lots do not have an adequate site to construct a new system and the property owner has few options. If the soil conditions are suitable and space is available, a property owner may be able to construct a mound system or a sand bioreactor with an onsite irrigation system to replace a failed septic system. For more information on mound, sand bioreactor or irrigation systems, consult OSU Extension Bulletins 813, 829, 860, and 876 which are for sale at local Extension offices.

If available, a home may be able to connect to a sewer that carries the wastewater to a system that can treat it. If no other options exist, the property owner may have to rely on a holding tank to collect and pump out sewage at considerable expense.

Why systems fail
Systems fail for three major reasons:  Inadequate design, poor construction practices, or the system is old and beyond its useful life.

Siting a system on unsuitable soil and improper construction are common errors.

Septic system age should also be considered. Tanks and pipes buried in the ground can be expected to last 20 to 30 years before they begin to deteriorate and require repair or replacement. Design and construction practices have improved over the past 30 years. Systems built before the 1970s may be inadequately designed by today's standards.

Avoiding system failures
Most failures can be avoided at the time of construction. The soil is the most important portion of any septic system. The soil must be carefully considered and protected during and after construction.

Three ways to avoid system failure should be considered.

1.  Analyze the soil in detail.
2.  Construct the soil in detail.
3.  Do not pipe sewage to the ditch or storm sewer.

To find a list of septic system designers, manuals on mound and bioreactor systems, and more information on how septic systems work, check the website for the OSU Soil Environment Technology Learning Lab, http://www.ag.ohio-state.edu/~setll

Co-author for this article is Brian Slater, assistan professor and Extension soil scientist, OSU School of Natural Resources.

Karen Mancl, professor and Extension water quality specialist, can be reached at 614-292-6007, or mancl.1@osu.edu. 

This column is provided by the OSU Department of Food, Agricultural, and Biological Engineering.