Did You Know that a properly designed and installed septic system can be the safest, most economical way to treat your wastewater as long as it is properly maintained? If you are like most homeowners, you probably never give much thought to what goes down your drain, or what happens to it. If you own a car and understand how important it is to do preventive maintenance (like changing your oil), then you can understand how maintaining your septic system can save you money and headaches "down the road". This guide can help you be sure that your septic system is used and maintained properly.


System Description.  A septic Tank system uses natural processes to treat and dispose of the wastewater generated in your home. It typically consists of a septic tank and a drain field or soil absorption field. The septic tank provides the first step in treatment. As wastewater flows into the tank, the heavier solids settle to the bottom to form a sludge layer and the lighter solids, greases and oils float to the top to form a scum layer. The liquid in the drain field where it is distributed via perforated pipes and then treated by the natural soil system. The diagram below shows the components of a typical septic system.

System Operation. A septic tank is simply a big concrete or steel tank that is buried in the yard. The tank might hold 1,000 gallons (4,000 liters) of water. Wastewater flows into the tank at one end and leaves the tank at the other. The tank looks something like this in cross-section:

septic tank

In this picture, you can see three layers. Anything that floats rises to the top and forms a layer known as the scum layer. Anything heavier than water sinks to form the sludge layer. In the middle is a fairly clear water layer. This body of water contains bacteria and chemicals like nitrogen and phosphorous that act as fertilizers, but it is largely free of solids. Wastewater comes into the septic tank from the sewer pipes in the house, as shown here:

Piping diagram

A septic tank naturally produces gases (caused by bacteria breaking down the organic material in the wastewater), and these gases don't smell good. Sinks therefore have loops of pipe called P-traps that hold water in the lower loop and block the gases from flowing back into the house. The gases flow up a vent pipe instead -- if you look at the roof of any house, you will see one or more vent pipes poking through. As new water enters the tank, it displaces the water that's already there. This water flows out of the septic tank and into a drain field. A drain field is made of perforated pipes buried in trenches filled with gravel. The following diagram shows a view of a house, septic tank, distribution box and drain field:

System components

A typical drain field pipe is 4 inches (10 centimeters) in diameter and is buried in a trench that is 4 to 6 feet (about 1.5 m) deep and 2 feet (0.6 m) wide. The gravel fills the bottom 2 to 3 feet of the trench and dirt covers the gravel, like this:


The water is slowly absorbed and filtered by the ground in the drain field. The size of the drain field is determined by how well the ground absorbs water. In places where the ground is hard clay that absorbs water very slowly, the drain field has to be much bigger. A septic system is normally powered by nothing but gravity. Water flows down from the house to the tank, and down from the tank to the drain field. It is a completely passive system. You may have heard the expression, "The grass is always greener over the septic tank." Actually, it's the drain field, and the grass really is greener -- it takes advantage of the moisture and nutrients in the drain field.

System Operation. The septic tank provides some biological treatment of the sludge and scum layers that accumulate there. The majority of treatment occurs in the drain field where the effluent enters the soil and is treated as it percolates to the groundwater. The soil acts as a biological and physical filter to remove harmful substances including disease-causing bacteria, viruses, toxic organics and other undesirable wastewater constituents remaining in the effluent


Why Maintain Your System? There are three important health reasons for maintaining your septic system.

  • The first reason is the health of your pocket book. Poor maintenance results in failed systems requiring repairs at a minimum and possibly system replacement. Repairs or replacement cost can be thousands of dollars whereas a periodic inspection and pumping cost about $200.00 - $400.00
  • The second reason is the health of your family, your community and the environment. Untreated sewage water contains disease-causing bacteria and viruses, as well as unhealthy amounts of nitrate and other chemicals. Failed septic systems can allow untreated water to seep into wells, ground-water and surface water bodies where people get their drinking water and recreate.
  • The third reason is the health of your economy. Contamination of water bodies by failed septic systems pollutes water supplies, closes recreational areas and creates offensive odors. Quality of life, recreational opportunities and tourism decline and with them the property values and economic vitality of the area.

How do you maintain your System? Proper care of your system require day-to-day management as well as periodic maintenance. It also requires that you know where your system is. The more you know about how your system operates and how it should be maintained, the better able you will be to protect your investment in your home and property, protect your family's health and protect your environment.


AN OUNCE OF PREVENTION IS WORTH A TON OF CURE! Committing a little to the care of your system can help to avoid the nightmare of a failing system. Assuming that your septic system was properly located, designed and installed according to state codes, you are now in the driver's seat for the care of your system. By following the recommendations below, you can help your system to work properly for the years to come.


  • Conserve water to reduce the amount of wastewater that must be treated and disposed of by your system. Doing laundry over several days will put less stress on your system.
  • Repair any leaking faucet or toilets. To detect toilet leaks, add several drops of food dye to the toilet tank and see if it ends up in the bowl.
  • Divert down spouts and other surface water away from your drain-field. Excessive water keeps the soil from adequately cleansing the wastewater.
  • Have your septic tank inspected yearly and pumped regularly by a licensed septic tank contractor. See the chart below for suggested pumping frequencies.
  • Keep your septic tank cover accessible for inspections and pumping. Install risers with lids if necessary.
  • Contact your licensed septic tank contractor whenever you experience problems with you system or if there are any signs of system failure.
  • Keep a detailed record of any repairs, and when the system was pumped out.

Suggested Pumping Frequency (Years)

  Number of people using system
Tank Size
1 2 4 6 8
1000 5 3 2 1 1
1250 10 6 3 2 1
1500 15 12 4 3 2
*Pumping your septic tank is probably the single most important thing you can do to protect your system. If the buildup of solids in the tank becomes too high and solids move to the drain-field, this could clog and strain the system to the point where a new drain-field will be needed.


  • Don't drive over your drain-field or compact the soil in any way.
  • Don't dig in your drain-field or build anything over it and don't cover it with a hard surface such as concrete or asphalt.
  • Don't plant anything over or near the drain-field except grass. Roots from nearby trees and shrubs may clog and damage the drain-line.
  • Don't use a garbage disposal or at least limit its usage. Disposals increase solids loadings to your tank by about 50%, so you have to pump you tank more often than normally suggested
  • Don't use your toilet as a trash can or poison your system and the ground water by pouring harmful chemicals and cleansers down the drain. Harsh chemicals can kill the bacteria that help purify your wastewater. See the list below for examples.
  • Don't put in a separate pipe to carry wash waters to a side ditch or the woods. This gray-water contains germs that can spread disease.
  • Don't pour additives into your system. The bacteria needed to treat wastewater are naturally present in sewage. Though additives might be needed occasionally, they do not eliminate the need for routine pumping of your tank.
  • Don't allow backwash from home water softeners to enter the septic system.
  • Never enter a septic system -Toxic gases from the tank can kill. If your system develops problems, get advice from your county health department or a licensed tank contractor.

image of toilet

Do Not Flush

Coffee Grounds Disposable Diapers Sanitary Napkins Cigarette Butts Fats, Grease or Oil Paints Thinners Photographic Solutions Dental Floss Kitty Litter Tampons Condoms Paper Towels Varnishes Waste Oils Pesticides

How to know if your system is failing

These symptoms tell you that you have a serious problem:

  • Sewage backup in your drains or toilets. This is often a black liquid with a disagreeable odor.
  • Slow flushing of your toilets. Many of the drains in your house will drain much slower than usual, despite the use of plungers or drain cleaning products.
  • Surface flow of wastewater. Sometimes you will notice liquid seeping along the surface of the ground near your septic system. It may or may not have an odor associated with it
  • Lush green grass over the absorption field, even during dry weather. Often, this indicates that an excessive amount of liquid from your system is moving up through the soil, instead of downward, as it should. While some upward movement of liquid from the absorption field is good, too much could indicate major problems.
  • The presence of nitrates or bacteria in your drinking water well. This indicates that liquid from the system may be flowing into the well through the ground or over the surface. Water tests available from your local health department will indicate if you have this problem.
  • Buildup of aquatic weeds or algae in lakes or ponds adjacent to your home. This may indicate that nutrient-rich septic system waste is leaching into the surface water. This may lead to both inconvenience and possible health problems.
  • Unpleasant odors around your house. Often, an improperly vented plumbing system or a failing septic system causes a buildup of disagreeable odors around the house.

Occasionally a system suffers an upset, when the septic tank bacteria are harmed or destroyed. This can happen if the home is vacant for a long period and the tank receives no fresh wastewater, or if strong cleaning agents are flushed down the drain. After a few days of normal use, the biological system in the tank will re-establish itself. In this situation the biological additives may help speed the recovery of the septic tank.

Could an additive harm my system?

The biological additives are unlikely to be harmful. The chemical additives could definitely harm your system. These products have the potential to sterilize your system temporarily. The resulting passage of raw sewage into the drainfield will hasten its failure. The acid and alkali products can corrode the plumbing and the tank. The organic solvents pass through the system unchanged. They can then infiltrate into the groundwater, creating a chemical plume that endangers nearby wells.

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