Q&A / 

Disposals Harm Septic Systems – Garbage!

DEAR TIM: My husband and I 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 disposer because the food scraps will clog the system. Is this true? If I do decide to install a disposer will I have to pump out my septic tank more frequently? What about septic tank additives? Do they work? Patsy M., Tortilla Flat, AZ

DEAR PATSY: I have heard that same claim from other people including some septic system professionals. The truth of the matter is that garbage disposers can be used with septic systems that have been sized and built properly and are maintained on a regular basis. Grease and oils are the only food waste I would not pour into the disposer. Grease buildup can cause major problems within a septic system.

Septic systems are very good at breaking down common body wastes and regular food wastes. A regular septic system accomplishes this using a two part system. The first part is the actual septic tank. These large containers come in sizes that range from 750 to 1,500 gallon capacities. The tanks are sized in accordance with the number of occupants in the house. 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 drainfield. The drainfield 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 partially treated wastewater flows from the other end of the tank to the drainfield. The waste water flows slowly through the drainfield 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. These bacteria work within the septic tank to begin the waste breakdown process. However, all too often people inject household chemicals, anti-bacterial soaps, and other items that can kill this beneficial bacteria. When this happens, the wastewater that flows into the drainfield can contain nearly invisible solid waste particles that can and will begin to clog the gravel and soil within the drainfield.

Standard garbage disposers actually help the breakdown process. The grinding action that happens each time you turn on the disposer actually increases the surface area of the food particles by hundreds of times. This allows the food particles to be broken down that much quicker by the bacteria within the septic tank. If the waste particles are not broken down quickly within the septic tank, they can settle to the bottom of the tank forming a thick layer of sludge. As the sludge mass increases, it effectively reduces the working size of your septic tank. This in turn causes sludge to build up even more quickly.

You can now purchase fantastic garbage disposers made especially for people with septic systems. These disposals differ from ordinary ones in that they come with a nifty liquid biochemical dispenser. Each time you operate the disposer, 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 breakdown the food waste. These added bacteria help to keep the bacteria count within the tank at a healthy, active level. Tests have shown that these new disposers actually minimize the amount of sludge buildup within a septic tank. The intervals between normal septic tank maintenance can increase thus saving you money.

Certain septic tank additives contain chemicals that can hurt your septic tank and contaminate natural groundwater resources. Check the label and make sure they do not contain toluene, chlorobenzene, vinyl acetate, and 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!

Author's Notes:

June, 2000

New Sink Switch for Disposers!

Do you operate your current disposer with a wall switch or a switch hidden in the sink base cabinet? There is a better way! Get a sleek sinktop switch from In-sink-erator. This handy switch mounts right on the sink deck, eliminates the need for a wall switch and simplifies the electrical installation. Available in either white or chrome, this switch will complement any kitchen decor. You can retrofit existing installations, but if you are building a new home, this is a must have item that you need to incorporate in your sink. For more information about In-Sink-Erator products, visit the Insinkerator Web site or call 800-558-5700.

Author's Note: We've received other questions with similar problems or questions. Here's one from Howard Stein of Oklahoma City, OK, regarding his home septic system.

"We have ten inches of snow and the temperature is near zero Fahrenheit. It will stay like this for several days.  Is it safe to use our washing machine (doing regular laundry) in this frigid weather since we have a septic tank and fear that the "arms" cannot properly dispose of large volumes of water into the ground?  Many thanks for your help."

Howard, typically in most septic systems, the tank and drainage fields are located well below the frost line.

Related Articles:   Septic Tank MaintenanceSeptic Tank Garbage DisposalGarbage Disposal for Septic Tank ManufacturerSafe Septic Tank Additives


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