Septic System Basics

By Frank G. Ross

Wastewater leaving a home must be treated and cleaned before it can be released into the environment.  In municipal locations this sewage is collected and routed to a treatment facility.  However, in rural locations homes will have their own onsite wastewater treatment system or individual sewage disposal system more commonly referred to as a septic system.  The EPA reports that one-fourth of US homes use septic systems.

A septic system consists of four main components: a pipe from the home, a septic tank, a drain field and the soil. 

The pipe carries the water from the house to the septic tank. 

The septic tank, a watertight container typically made of concrete, fiberglass or polyethylene, is buried somewhere near the home.  It holds the wastewater long enough for the solids to settle out and the oil and grease to float to the surface.  The design of the interior is intended to prevent the sludge and scum from exiting the tank. 

The wastewater leaving the tank ends up in the drain field for further treatment by the soil.  Each time new wastewater enters the septic tank partially treated wastewater is discharged into the drain field.

Once the water reaches the drain field, it percolates into the soil through a series of perforated pipes.  The soil then filters the wastewater and soil microorganisms decompose many contaminants in the wastewater.  Suitable soil is needed for the system to work properly.  Alternative systems are available for areas that don’t have suitable soil.

As with many other systems in the home, the septic system requires regular maintenance or it can fail.  A failed system can be expensive to repair or replace.  The cause of many failures is poor maintenance.  The EPA recommends that a typical system be inspected at least every three years by a professional.  The inspection should include locating the system, uncovering access holes, flushing the toilets, checking for signs of back up, measuring the scum and sludge layers, identifying any leaks, inspecting mechanical components and pumping the tank if necessary.  The tank should be pumped every three to five years or as recommended by the inspector.  Find a service provider by logging onto the Septic Yellow Pages at www.septicyellowpages.com. 

Causes of failure include household toxic chemicals and cleaners, large quantities of water entering the system, excess solids directed to the septic tank and improper design or installation.  A septic system functions best when users take precautions to avoid these sources of breakdown. 

Keep oil-based paints, solvents, disinfectants, pesticides and large volumes of toxic cleaners from entering the septic system.  They are harmful to the friendly bacteria needed to treat the wastewater.  The system should be able to accommodate small amounts of mild household cleaners.  Don’t use caustic drain openers for a clogged drain.  Instead, use boiling water or a drain snake.

As mentioned above, water flows out of the septic tank as new water flows into it.  For this reason large amounts of water flowing through the system don’t allow the partial treatment in the tank to take place. In fact, solids can even be stirred up and pushed out to the drain field which may cause a clog.  Don’t drain hot tubs or swimming pools into the septic tank or drain field.  Spread laundry loads out over the week rather than doing several in one day. 

Using a garbage disposal frequently can significantly contribute to the amount of sludge or scum in the tank leading to a need for more frequent pumping.  Also, don’t flush dental floss, feminine hygiene products, condoms, diapers, cotton swabs, cigarette butts, coffee grounds, cat litter, paper towels, or other items that can potentially clog the system and damage the components.

By following water efficient practices, homeowners can reduce the amount of wastewater the system needs to treat.  Having the tank and drain field regularly inspected reduces the chance of failure.

The drain field is an important and somewhat delicate part of the septic system.  Care for it in the following ways:  Plant only grass over and near it.  Tree roots can clog or damage it.  Don’t drive or park vehicles on any part of it because the soil may become compacted and pipes may be broken.  Direct rainwater and other surface water away from the drain field so as not to overload it.  Flooding the drain field slows down or stops the treatment process and can cause plumbing fixtures to back up.

A complete septic inspection is generally excluded from a home inspection; however the septic system must be in good working order when a home is sold.  For more information, consult local health officials, the local plumbing inspector or the EPA’s website at www.epa.gov/owm/septic.  Other great sources of information are the National Small Flows Clearinghouse (www.nesc.wvu.edu/nsfc/nsfc_septicnews.htm), the Rural Community Assistance Program (www.rcap.org) and the National Onsite Wastewater Recycling Association, Inc. (www.nowra.org).

Frank Ross is a Certified Utah Home Inspector for Pillar to Post Professional Home Inspection and a full member of the National Association of Certified Home Inspectors and a member in good standing with the Utah Better Business Bureau.  Readers may contact Mr. Ross at (435) 867-6400 or frank.ross@pillartopost.com or www.pillarposthomeinspection.com