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Garbage disposals can be used with septic systems

(ran HP HC editions)

Question: We live in a rural area that is not served by public sewers. Our household wastewater flows to a septic tank.

I have been told that I can't have a garbage disposal because the food scraps will clog the system. Is this true?

If I do decide to install a disposal, will I have to pump out my septic tank more frequently? What about septic tank additives? Do they work?

Answer: Garbage disposals can be used with septic systems that have been sized and built properly and are maintained regularly. Grease and oils are the only food waste I would not pour into the disposal. Grease buildup can cause major problems within a septic system.

Septic systems are very good at breaking down common body wastes and ordinary food wastes. A regular septic system accomplishes this with a two-part system.

The first part is the actual septic tank. These containers range in size from 750 to 1,500 gallons. Tanks are sized in accordance with the number of the home's occupants. Your county health officials often have sizing guidelines.

The primary purpose of the tank is to collect and separate the components of the waste that flows from your house into the septic system. The tank also acts as a holding area where the initial breakdown of the waste takes place.

The second part of the septic system is the drain field, which consists of interconnected perforated pipes surrounded by gravel. The pipes fan out from the septic tank.

The final cleansing of waste occurs within the drain field. Each time new water waste is added to the septic tank, some 1- to 2-day-old, partly-treated wastewater flows from the other end of the tank to the drain field.

The waste water flows slowly through the drain field pipes and into the surrounding gravel. Organisms within the gravel and soil act as natural filters, removing toxins, bacteria, viruses and pollutants.

The waste that leaves our bodies and typical food waste contain bacteria, which work within the septic tank to begin the waste breakdown process. Too often, people inject household chemicals, antibacterial soaps and other items that can kill this beneficial bacteria.

When this happens, the wastewater that flows into the drain field can contain nearly invisible solid waste particles that clog the gravel and soil within the drain field.

Standard garbage disposals actually help the breakdown process. Their grinding action increases the surface area of the food particles by hundreds of times, which increases the speed with which food particles are broken down by the bacteria within the septic tank.

If this does not happen, the particles can settle to the bottom, forming a thick layer of sludge. As the sludge mass increases, it effectively reduces the working size of your septic tank, which causes sludge to build up even more quickly.

You can now purchase garbage disposals made especially for people with septic systems. These disposals come with a liquid biochemical dispenser.

Each time you operate the disposal, some of the biochemical additive is automatically injected and mixed with the food sludge. Hundreds of millions of beneficial bacteria are transported into the septic tank and immediately begin to break down the food waste. These added bacteria help to keep the bacteria count within the tank at a healthy, active level.

Tests show that these new disposals minimize the amount of sludge buildup within a septic tank. The intervals between normal septic tank maintenance calls can increase, saving you money.

Certain septic tank additives contain chemicals that can damage your septic tank and contaminate natural groundwater resources. Make sure that they contain no toluene, chlorobenzene, vinyl acetate or isoprene. Never poison your septic tank with gasoline, paint thinners, harsh cleaners, pesticides or antifreeze. Always keep in mind that you want the beneficial bacteria within the tank to thrive and survive.

Send for Builder Bulletin No. 220 listing 30 safe septic tank additives, septic garbage disposal manufacturers and other tips on maintaining septic tanks. Send $3 and your name and address to Tim Carter, c/o St. Petersburg Times, P.O. Box 36352, Cincinnati, OH 45236-0352, or visit his Web site at

Tim Carter is a licensed contractor. Got a question for him? Call toll free from 10 a.m. to noon today at (888) 737-1450 on his radio call-in show (not broadcast in the Tampa Bay area).