IS1437 Maintain a Sanitary Septic System

Some homes are connected to a community sewer system that channels liquids and human wastes through underground pipes to sewage treatment plants. There, wastes are treated before they are discharged into streams and lakes.

In Mississippi, most rural homes, however, have individual septic systems that handle wastes in a different manner. A septic system carries wastes into underground tanks where solid materials settle to the bottom. The waste liquid is allowed to flow into pipes that disperse it slowly over a large area of soil (drain field) where it is further broken down by natural-occurring soil microorganisms.

Septic tank problems usually can be divided into those related to the septic tank itself and those related to the drain field. An important extenuating fact of septic-tank-system problems is that the system is hidden below the ground surface. Coupled with the generally disagreeable nature of the process, this makes it easy to ignore necessary maintenance.

Septic Tank Problems

Excessive sludge accumulation and inadequate tank size are common septic tank problems.

The principal septic tank problem occurs when the inert-solids accumulation occupies too much of the septic tank capacity and greatly reduces the treatment volume of the septic tank. Residence time of household wastewater in the septic tank is inadequate, and partially treated wastes are discharged to the drain field. This condition promotes clogging the drain field and reduces its capacity to dispose of septic tank effluent.

Also, if excessive quantities of sludge are present, the sludge may be discharged to the drain field. This can promote plugging of the drain field. The recommended solution to this problem is to have the septic tank contents--sludge, scum, and liquid--pumped out.

Because of the variety of conditions that can be found in individual homes, it is not possible to predict septic-tank-cleaning intervals. You can have the tank inspected annually, however, and cleaned when the sludge depth at the outlet end is one-half the total liquid depth in the septic tank. Another accepted general rule is to have the tank pumped out every 3 to 5 years.

Overloading the System

Another usual septic tank problem--inadequate size--results in poor treatment and unnecessary load into the drain field. Septic tank size is commonly based on the number of bedrooms in the home served. The number of bedrooms is an indicator of the number of people serviced and the quantity of waste to be treated. Recommendations include the following:

No. of bedrooms		Tank capacity gal (cu ft)
2	or fewer	750	(100)
3		900	(120)
4		1,000	(133)

Septic tanks that may have been adequate in size may no longer be when family size increases or as the house is enlarged.

Households use and flush away some compounds that may be toxic in the case of large quantities or accidental spills. These could reduce the effectiveness of the septic tank. However, in normal quantities, common household materials--for example, detergents, bleaches, disinfectants, and drain cleaners--have no significant effect on the function of a properly sized septic tank. Do not make excessive demands on your system's capacity. Several loads of laundry in a day, extremely long showers, or whirlpool tubs put extra strains on a septic system. Do not put bacon drippings, cooking oils, and other greasy wastes down your drains because they can clog the drainage field.

Never put storm water or runoff from roofs in a wastewater system. Too much water flowing too fast through the system can cause solid materials to pass into the drain field without undergoing the gradual anaerobic digestion process that takes place in the tank.

Drain Field Problems

Drain field problems often are related to overloading the soil with liquid (hydraulic overload), plugging the soil pores with excess organic matter from the septic tank (organic overload), and roots plugging the drain pipe.

An inadequate hydraulic capacity of the drain field might be corrected by adding to the drain field. Base such additions on a reliable percolation test. A dosing chamber or an alternate loading of multiple drain field segments can be used in some cases.

Excess organic loading in the drain field is probably a two-part solution. First, the excessive organic load is likely because of an inadequate tank size or excessive sludge accumulation. Solving the first part of the problem first is essential. It may require a larger septic tank, reducing the organic load to the existing septic tank, or cleaning out the tank. The second part of the solution is to restore the hydraulic capacity of the drain field.

Tree roots, especially those of a water-seeking tree such as a weeping willow can plug drain- field lines. One solution is to employ a commercial establishment to cut and mechanically remove the clogging root mass. This may be necessary to remove the offending roots.

Another solution to less severe cases of clogging roots is chemical treatment. A time-honored (though scientifically unproven) remedy is to add copper sulfate to the drain field. The recommended dosage ranges from a few crystals to a few pounds, depending on the extent of the problem. Small quantities, as a preventative, may be added through a household drain and passed through the septic tank. Add larger quantities directly to the drain field. Commercial products containing copper sulfate are available for this purpose.

Discharge systems must maintain all of the wastewater on the property of the generator. A minimum distance of 50 feet must be between the property line and the point where the wastewater will stop flowing, not the discharge point during dry and wet seasons.

Information Sheet 1437
Mississippi State University does not discriminate on the basis of race, color, religion, national origin, sex, age, disability, or veteran status. Extension Service of Mississippi State University, cooperating with U.S. Department of Agriculture. Published in furtherance of Acts of Congress, May 8 and June 30, 1914. RONALD A. BROWN, Director

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