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Garbage Disposals for Septic Tanks: What You Should Know

Garbage Disposal under counter designed for septic tanks

If your home uses a septic system you likely either don't have a garbage disposal, or you're wondering if you can have a garbage disposal with a septic tank. Although, many homeowners choose to play it safe and not install one, the fact of the matter is, you actually can use a garbage disposal with a septic tank.

In fact, there are garbage disposals especially designed for septic systems. We'll show you our top septic tank garbage disposal recommendation, and explain how to use a garbage disposal safely with a septic tank.


In-Sink-Erator 3/4 HP Garbage Disposal, 120 Voltage - Evolution Septic Assist(TM)

Best Garbage Disposal for Septic Tanks

Although, technically any garbage disposal will work with a septic tank, it's a good idea to buy one that's designed specifically to help break down food in a septic system.

All garbage disposals chop food into small pieces, but garbage disposals such as the InSinkErator Evolution Septic Assist will actually add a shot of Bio-Charge Fluid into the grind chamber.

InSinkErator Evolution Septic Assist

InSinkErator Evolution Septic Assist 3/4 HP Household Garbage Disposal

InSinkErator Evolution Septic Assist Garbage Disposal

The Bio-Charge Fluid contains roughly 300 million micro organisms that begin to breakdown the food waste before it even leaves the garbage disposal!

The micro organisms continue working within the septic system to breakdown food solids more quickly.

Although, you'll always need to be careful when using a garbage disposal with a septic tank, using one specifically designed for the job can eliminate the need to add other products to your septic system. 

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How a Septic Tank Works

Before discussing how to use a garbage disposal with your septic tank, let's first look at how the septic tank actually works. 

We know, this isn't really what you want to talk about, but understanding how your septic system works will help you understand how to use a garbage disposal with your septic system.

Septic Tank System

All of the water that drains from your home runs through your septic system. This includes water used in sinks and showers, and of course, when you flush the toilet.

As the waste water enters your septic tank, it passes into the first section where it separates into 3 layers: Scum (grease and oil) makes up the top layer; Liquid, in the middle; and the Sludge (solids) fall to the bottom.

Microbes begin to break down the solids in the sludge layer, and excess water and smaller sludge particles pass into the second compartment where the microbes continue to degrade the sludge.

Finally, the excess liquid flows into ta leaching bed, or sometimes called a drain field where the filtering continues.

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How a Garbage Disposal Affects Your Septic Tank

The food waste ground in your garbage disposal is chopped into tiny pieces and washed down the drain into your septic tank.

The food particles settle in the sludge layer, and compared to other solids such as toilet paper, they take more time to breakdown.

If you only use your garbage disposal sparingly and are careful about what you grind, you probably will be just fine. However,  depending on how frequently you use your garbage disposal, the natural microbes may not be able to decompose the sludge layer fast enough.

When this happens, the sludge will overtake the tank and you'll need to have someone out to pump it from the septic system.

Food scrapes in a kitchen sink

Should You Use a Garbage Disposal with a Septic Tank?

Ask any plumber, and he'll likely tell you NO, or at least be extremely careful and proceed with caution.

Septic systems have a very delicate bacteria ecosystem and disrupting it, or overwhelming it could require more frequent pumps . . . which of course, means more money and headache.

But that doesn't mean you're not without options.

Garbage Disposal Options

As mentioned above, there are specially designed garbage disposals for septic tanks. These disposals typically include a solution of enzymes to help breakdown the food waste and sludge.

InSinkErator sells the Evolution Septic Assist. Which is a 3/4-hp garbage disposal that injects their exclusive Bio-Charge Enzyme Treatment to add over 300 million enzyme-producing microorganisms to your septic tank.

InSinkErator Evolution Septic Assist 3/4 HP Household Garbage Disposal

InSinkErator Evolution Septic Assist Garbage Disposal

Of course, another option is to bypass the garbage disposal altogether and start composting. You can select a place in your yard and add a compost pile put your food scraps.

In a short period of time, you'll have wonderful compost that can be added to your garden or flowerbeds. However, it's a good idea to have an enclosed bin with a cover for food waste, or rats and other critters may discover your scrapes.

We like tumbling composters like the one in the picture below manufactured by FCMP Outdoor.  Learn more about this product here. They are off the ground, covered and protected from critters, and you can give it a tumble when you walk by.

IM4000 Dual Chamber Tumbling Composter (Black)

Eggs shells and other items not to put down garbage disposal with a septic tank

Foods to Avoid Grinding in a Garbage Disposal on a Septic Tank

Since a garbage disposal grinds food scraps into small bits, not a smooth liquid, it makes it extremely easy to overfill the sludge layer in your septic tank.

By paying attention to what you're putting down your disposal, you can protect your septic system from needing a pump sooner than you'd like.

Much of the ground food scraps will become hard and granular after grinding, however using your garbage disposal for soft foods won't cause as much stress on your septic tank.

Foods such as oranges, bananas, and tomatoes add fewer solids into septic systems, lowering the need for pumping.

Don't Grind These Foods in Your Garbage Disposal With a Septic Tank

Some foods such as coffee grounds, rice, pasta, and grease/oil should never be put down your garbage disposal, but there are a few others that you should avoid:

  • Egg Shells
  • Potato Peels
  • Grapes
  • Oatmeal
  • Beans
  • Seafood Shells
  • Avocado Seeds
  • Nuts
  • Asparagus
  • Fruit Pits

Any of these items could damage your garbage disposal with or without a septic tank, but if you have a septic tank they could be especially problematic.

With a little extra care and effort, using a garbage disposal with a septic tank is perfectly fine.