A Home Buyer's Guide to Septic Systems

Overview of Septic Systems

The purpose of a home's subsurface sewage disposal system (septic system) is to dispose of the water generated by the occupants in such a manner that the soils on the property can disperse it without causing an adverse effect on ground water and in turn on public health and the environment. To accomplish this a septic system consists of the following elements:

1. A sewer line that connects the home's plumbing to the septic tank;

2. A septic tank that allows for the settling of soils and provides the initial treatment of the sewage. 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 and to prevent solids from leaving the tank. Tanks installed since January 1991 usually consist of two compartments in order to do a more effective job of attaining the above objective;

3. A distribution system that directs the flow of effluent from the septic tank to the leaching 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;

4. A leaching system, which disperses the sewage effluent into the surrounding natural soils. There are many types of leaching 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.

For a leaching system to function properly it must:

1. Provide enough application area. The application area is the amount of surface area of soil within the leaching system where sewage effluent is applied (referred to as "wetted" area). The amount of application area needed for a given house depends on the characteristics of the soils on the property and the daily flows (in gallons) generated from the house.

2. Be surrounded by natural soil conditions which will be able to dissipate and disperse the discharge without becoming over saturated.

3. Provide enough capacity to store effluent during periods of unusually heavy use or when rainfall or subsurface flooding reduces the ability of the system to disperse the liquid. Note: Curtain drains or ground water interceptor drains are sometimes installed upgrade of the leaching system to minimize high ground water conditions.

It is important to realize that, once a system has been installed, only one of the above factors can be controlled by the homeowner. The homeowner can control how much water is actually being discharged to the system. Since each system has a set maximum capacity, it behooves the homeowner not to exceed that amount.

If a system starts to experience difficulties, what are some of the common symptoms?

1. Plumbing fixtures may exhibit difficulty in releasing their contents (slow draining, bubbling, backups, etc.). This condition may be system-related but it could also indicate just a clog in the interior piping or sewer line. You should have the interior piping checked before proceeding with an investigation of the sewage disposal system.

2. Large volume discharges (such as, washing machines, dishwashers and bathtubs) cause either a backup, as noted above, or, an overflow of sewage above the septic tank or leaching field. If this condition is usually at its worst during and/or directly following a heavy rain event, then the septic system is indeed suspect. If backup alone occurs independent of wet weather, you might first check for a partial blockage of the main drain that has occurred some distance from the house. In such cases a small discharge will simply be held by the main waste pipe, draining slowly past the blockage, while a large discharge will cause a backup.

3. Foul septic odors in storm drainage piping, catch basins, footing drain piping or curtain drain discharges may indicate that sewage from your property or an adjacent one is entering these ground water systems.

Sources of Information about your particular system

What can a prospective purchaser of a home do to gather as much information as possible relative to the present condition of a system and about possible future expenses associated with the septic system? Here are a few suggestions:

Obtain Information from the present property owner

• Ask for any drawings regarding the actual location (an "as-built drawing) of the existing septic system.

• Ask for the records regarding maintenance of the system; Has the septic tank been pumped at a frequency of at least 3 to 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.  Have any of the symptoms described earlier manifested during the life of the system?

Do a Site Inspection of the Property

• Once the locations of the septic tank and leaching fields are known, walk over the entire area and observe whether there is any evidence of a sewage overflow condition. Greener grass in the leaching area may not necessarily indicate a system problem. If, however the area is completely saturated and odorous you should be very concerned. It most likely indicates an active failure.

• Try to get a sense of how natural conditions are effecting the capacity of the property to disperse water. Is the sewage disposal area located In a depression which would have a tendency to collect run-off of rain water? Is the lot flat? Is there a water course of wetland (swamp) near the leaching system? Is the system virtually at the same elevation as nearby wetlands? Are there steep slopes and/or ledge outcrops which reduce the available area for leaching purposes? All of the above factors could indicate that the existing system will experience difficulty or, that there may not be much additional area suitable for sewage disposal on the lot if needed in the future.

Go to Municipal or State Health Department to Review the Property's File

• Ask the 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?

• Ask for the records regarding maintenance of the system; Has the septic tank been pumped at a frequency of at least 3 to 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?

• 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 wm 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.

Obtain Additional Information from Outside Sources

1. Presently many home sales are contingent upon a home Inspection. Part of the inspection may include a test of the existing septic system. [Note: Septic Tests are beyond the scope of a professional home inspection but are sometimes offered as an additional for-fee service by some home inspectors who serve areas where private systems are common.] The people performing these tests are often involved in the maintenance of septic systems and may not have a complete understanding of how such systems function. Therefore, the conclusions reached from these tests are often misleading.

   Three common septic tests performed during or concurrent with a home inspection are:

   1. The Dye 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 can take from 20 minutes to several days to appear and the amount of water introduced with the dye is critical.

   2. Probe Test is a procedure whereby the inspector attempts to locate the "key" elements of the system (septic tank and leach fields) and determine if they are experiencing hydraulic distress (meaning the septic tank and fields are flooded). This test is basically inaccurate since it only takes a single "snapshot 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; 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.

   3. The flooding "test" is actually the process of discharging a vast amount of water into the existing system. Depending on the number of fixtures utilized, an additional 500 to 1,000 gallons of water can enter the  system during the course of an inspection. The inspector then examines the leaching area to observe any signs of an "overflow condition." If none is noted, it is assumed the system is functioning property. This type of test is most disturbing since it can actually do harm to the system by "artificially" flooding the septic tank and fields. This could lead to suspended solids escaping the tank, causing increased clogging to the leaching fields. Also, the results of such a test can be misleading in that the prior use of the system (both over and under utilization) will have a direct bearing on the outcome of the "test." The Septic Information Website describes appropriate procedures for performing various septic tests based on a national survey of inspection and engineering practices.

2. Use the Soil Conservation Service, County Soil Maps, if available, to try to identify the type of soil most likely present on the site in order to predict the feasibility of future repairs to the existing leaching system.

3. 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 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 property; not wanting to spoil the sale of a friendly neighbor, etc.)

4. Hire your own consultant either a professional engineer specifically familiar with septic system design and repair or, a licensed septic system installer, who performs a great deal of work in the particular town. They can give you advise as to the condition of the soils and septic systems in the area and what might be expected (especially pertaining to costs) if/when you find problems with the existing system.

5. Obtain water meter readings (if the home is serviced by a municipal water supply) to determine what the present occupants of the home are utilizing. Then compare those results with what your family is presently using. If your family is using significantly more water than the former occupants, you may be asking for trouble if the sewage system is undersized by today's standards.

6. Additional useful information which may be available from the service company who has pumped the tank recently including the following:

   • Type of tank material - old steel tanks may be at or end of their useful life

   • Tank size - along with usage determines appropriate pumping frequency and system capacity

   • Evidence of damage to tank components - broken baffles mean the leach fields are probably ruined

   • Evidence of backflow into the tank during start of pumping - indicates flooded leach field, probably failed

   • High sludge level and/or excessive floating scum level - indicate high risk of having pushed solids out into the leach field, destroying it

   If the system has not been cleaned in several years and if the seller will permit, have the tank pumped to obtain this additional information.  If the tank location is unknown, extra costs will be involved to locate and excavate it - steps to which a seller is likely to object.

Final Overview

When buying a home, especially one that is old and does not have a sewage disposal system that meets today's standards, the fundamental question that should be answered is: "When the existing system fails, how will we repair it and how much will repairs cost? If accurate soil test data is not available through the local health department the only sure way of answering the 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. Therefore the more information a buyer can obtain, the better able he or she will be able 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.

 

 [This text was copied, edited and supplemented from a public document of  
    the Connecticut State Department of Health Services.]

Additional information may be obtained from the State of Alaska, Department 
of Environmental Conservation at:
http://www.state.ak.us/dec/water/wwdp/onsite/buying_a_home.htm