Prospective buyers of a single family home often have many questions regarding the septic system serving the dwelling. They may wish to know what the existing septic system consists of, if it's working properly, its predicted longevity or the cost of replacing the system. The information that follows will help answer those questions.

The purpose of a home's subsurface sewage disposal system (septic system) is to dispose of the waste water generated by the occupants in such a manner that the soils on the property can disperse it without causing an adverse effect on groundwater and, in turn, on public health and the environment. To accomplish this a system consists of the following elements:
  • A sewer line which connects the home's plumbing to the septic tank.
  • A septic tank which allows for the settling of solids and provides the initial treatment of the sewage. This is where waste material is broken down by bacterial action. A properly functioning septic tank will reduce pollutant levels and produce an effluent of fairly uniform quality. This is accomplished by providing inlet and outlet baffles to reduce the velocity of liquid moving through the tank. New tanks (installed since January, 1991) consist of two compartments in order to accomplish this more effectively.
  • A distribution system which directs the flow of effluent from the septic tank to the drainage system in such a manner to insure full utilization of the system. Most systems are "gravity" systems, meaning the flow runs through piping and distribution boxes without the assistance of any mechanical device such as a pump or siphon.
  • A drainage (leaching) system which disperses the sewage effluent into the surrounding natural soils. There are many types of drainage systems. The specific type utilized on a particular property is usually dependent on the soil conditions which exist on the site. Most residential installations utilize stone filled leaching trenches, but galleries, pits and beds have historically been used.
Where can a prospective purchaser of a home gather as much information as possible relative to the present condition and possible future expenses associated with the existing septic system? Here are a few suggestions:

The Present Property Owner
  • Ask for the records regarding maintenance of the system: Has the septic tank been pumped at a frequency of at least 3- 5 years?  What pumping contractor was used?  If the system contains a pump, how often has it been maintained?  If major repairs have been made, when and to what extent?
  • Ask about the past performance of the system.
The Town Health Department
Ask the town sanitarian to review the file with you. Is there enough information in it for him/her to give you an opinion on how the existing system and/or lot meets present health code requirements?
  • Your goal is to confirm and supplement information received from the property owner.
  • Obtain guidelines concerning the proper maintenance of a subsurface sewage disposal system.
  • If you are contemplating an addition to the home or plan on renovating an unfinished basement, discuss the possibilities with the sanitarian and determine the procedures you would have to follow to accomplish your plans. In some cases, it will not be possible to "enlarge" an existing home.
  • Ask about the general neighborhood, the frequency of repairs, ability to install proper size repair systems, average life of systems in the area, etc.
Additional Information From Outside Sources
Presently, many home sales are contingent upon a home inspection. Depending upon whether or not the present owner of the property will permit it, examining key elements of an existing sewage disposal system is the most reliable means to determine the present condition of the system. This examination is best done by a septic tank servicing company. Examining the inside of the septic tank(s) and distribution boxes may indicate that the system is experiencing difficulties dispersing the volume of sewage generated by the home. If access to the existing system is not available, home inspectors sometimes use other methods to ascertain the status of an existing system. Unfortunately, some home inspectors performing these tests do not completely understand how a system functions, therefore, the conclusions reached from these tests can be misleading. (For example: testing a system in summer may indicate a functioning system, when in spring that same system may be under groundwater and not be able to function properly). A home inspector may offer to perform the following tests:
  • The Dye Test. This test is used to trace the movement of septic tank effluent into the leaching system. The theory is that if the dye "surfaces" to the ground or appears in a brook or catch basin, the system is in trouble. Although this is indeed true, the opposite result does not necessarily mean the system is functioning or will function properly in the future. In order for the dye to appear, it must flow through the septic tank and leaching fields prior to arriving at the breakout point. This would usually take a large amount of water and sufficient time to occur and most home inspections do not last long enough to fulfill this requirement. This type of test would only detect grossly failed systems (ones which have a direct discharge of sewage to the environment). Some mortgage companies have been known to require this test.
  • The Probe Test. This is a procedure whereby the inspector attempts to locate the "key" elements of the system (septic tank and drainage fields) and determine if they are experiencing overflow conditions (meaning the septic tank and fields are flooded). This test is basically inaccurate since it only takes a single "snapshot" of the condition of the system. It may be a "good" day for the system (very little water was used by the homeowner that day, the house may have been empty for some time or it may be the middle of the summer when soil conditions are at their best) and a judgment is being made with very little long-term information.
  • The Flood Test. Sometimes referred to as a "push test", the Flooding Test is actually the process of discharging a substantial quantity of water into the existing system to simulate a typical "peak" usage of water by a family. The purpose to the test is to expose those systems which no longer have the capability to disperse "peak" flows and, therefore, may not be adequate to satisfy the needs of the prospective buyers. After a certain amount of water is "flushed" down sinks, tubs and toilets, the inspector examines the leaching area to observe any signs of an "overflow" condition. If an "overflow" is noted, the conclusion reached by the inspector is that the system is not functioning properly.
    It should be noted, however, that ''passing'' the test does not necessarily mean that the system is working properly. This type of test is conducted by many inspectors, who feel it would be a disservice to their clients not to obtain information on the present status of an existing system. We, however, have concerns that unless this test is performed in a responsible, site specific manner, it could cause harm to the existing system or lead to erroneous conclusions.

  • If this test is conducted, we suggest the following items be considered before conclusions are reached:
  • The present occupancy of the home.
  • The possible water usage of the occupants within the last 24 hours prior to conducting the test
  • Soil conditions in the leaching area such as, the degree of saturation due to groundwater levels, rain fall events or time of year.
  • The application of water to the system (by running water through the plumbing fixtures) which must be performed in a slow, uniform manner to prevent a "slug" of water from entering the septic tank and disturbing the contents.
  • The procedure be limited to the amount of water utilized for the test based on the information listed above but should not exceed 50 gallons per bedroom in a fully occupied home (two people per bedroom).
To repeat: the above testing is meant to discover obvious malfunctioning septic systems. None of the above tests can lead to a guarantee that the existing sewage disposal system for a home will continue to work properly in the future. The best option is to have the septic system evaluated by a qualified septic tank service company prior to closing.

Talk to neighbors about the general performance of septic systems in the area and specifically the system on the property you're interested in. However, this is suggested only for those comfortable in approaching this subject with strangers and with the realization that the information gathered may not be totally factual for various reasons (devaluation of their own properly, not wanting to "spoil" the sale for a friendly neighbor, etc.).

Hire your own consultant, either a professional engineer who specializes in septic system designs or a licensed septic system installer who performs a great deal of work in that particular town. They can give you advise as to the conditions of the soils and septic systems in the area and what might be expected (especially pertaining to costs) if you did have problems with the existing system.

It is our opinion that when buying an existing home, especially one which is old and does not have a sewage disposal system which meets today's standards, the fundamental question which should be answered is: If the existing system fails, how will we repair it and how much will those repairs cost? If accurate soil test data is not available through the local health department, the only sure way of answering this question is to actually perform all the deep hole testing and percolation tests required by code. As you can understand, most sellers would take a dim view of prospective buyers wanting to tear up their property to perform these tests. It follows then that the more information a buyer can obtain, the better able he or she will be to judge the adequacy of the existing system and what will most likely be required to repair the system when needed. In that way, the buyer will not be caught unaware when that day arrives since it was part of the financial assessment establishing the value of the property at the time of purchase.

Phone/Fax (203) 874-3449