Of all the modern conveniences afforded to us these days, garbage disposals are possibly the most detrimental home appliance to the functioning of your septic system. While you do have to be careful about staggering the use of washing machines and dishwashers to ensure you don’t overwhelm the septic tank with greywater, garbage disposals create problems by inundating your septic system with solids, often fatty solids. Fats, oils, and greases (FOGs) create their own set of issues for your septic system, and the onslaught of food solids puts added strain on the bacteria working hard in your septic tank. CAPE COD SEPTIC SERVICES strongly recommends you do not use a garbage disposal with your septic system, but if you must, we urge you to do so minimally.


One of the biggest problems created by garbage disposals for septic systems is related to homeowners using them as trash cans for all of the home’s food waste. Anything and everything that will fit down the drain is often put through the garbage disposal. In many cases, homeowners will cram the contents of weeks’ worth of forgotten leftovers, the grounds from their daily coffee, and food bits (like egg shells, potato peels, and fruit pits) down the disposal. All of this finds its way to the septic tank, where bacteria will work, tirelessly, trying to break it down. Regardless of how big your septic tank is, there is not nearly enough bacteria present to break down these solids, as well as those found in the rest of the home’s wastewater. Many of these solids – egg shells, coffee grounds, fruit pits, etc. – will never be broken down. These solids not only overwhelm the bacteria in your septic tank, but because they cannot be broken down, add significantly to the layer of sludge in the bottom of your tank. In fact, when our technicians service a septic tank, they are immediately able to identify a home with a garbage disposal when they find piles of food caked under the inlet pipe of the septic tank. The added strain a garbage disposal puts on your septic system will lead to a need for more frequent pumpings and will negatively impact your septic’s bacterium, making it less efficient in treating your home’s wastewater.

Alternative to Using a Garbage Disposal with Your Septic System

While we cannot overstate the negative impact of having a garbage disposal feed into your septic system, we understand every home creates food waste that must otherwise be managed. Rather than pouring these down the drain, composting is a more environmentally friendly alternative to garbage disposals. Composting is the practice of collecting organic materials in a special composting bin and allowing them to decompose. These organic materials break down naturally, leaving behind an organic and potent fertilizer that can be used to feed your garden, lawn, or indoor plants. Composting not only keeps food waste out of your home’s septic system, but also out of the landfills, where it creates methane (a greenhouse gas).

Using a Garbage Disposal with Your Septic

  • In some instances, garbage disposals are already installed when a homeowner buys a home with a septic system. Ideally, homeowners would remove the garbage disposal to avoid any temptation to funnel food waste into the septic tank. In the state of Massachusetts, garbage disposals may not be used with a septic system unless the system has been specifically designed to accommodate a garbage disposal.

But if you must use a garbage disposal, please follow these guidelines.

Use your garbage disposal minimally.

And we mean minimally! Break the habit of emptying your leftovers or coffee grounds into the drain (in fact, coffee grounds are a great addition to your compost bin). Never throw food into your sink to be processed by your disposal. Only use the disposal to clear out crumbs or remnants left behind after you’ve washed your dishes.


  • Fibrous or stringy foods, including celery, asparagus, or corn husks – They can get tangled and create clogs deep in your plumbing or within the septic tank itself.
  • Coffee grinds – The bacteria within your septic system cannot break these down, and they add significantly to your tank’s layer of sludge.
  • Fats, oils, and greases (FOGs) – These may appear to smoothly glide into your drain when they’re hot, but they become solid as soon as the temperature dips below freezing and add significantly to your tank’s layer of scum.
  • Egg shells – The bacteria in your septic tank cannot break these down, and because they float, they can cause other significant problems once inside your septic tank. These are another wonderful addition to your compost pile though!
  • Any starchy food – Whether beans, rice, or pasta, these starchy foods expand once they hit water (even when fully cooked) and lead to significant clogs within your plumbing and especially in your septic tank.
  • Potato peels – The starch in potato peels is especially damaging because it combines with water to form a glue-like substance that clings to pipes, creating clogs and all sorts of problems for your septic. The nutrients in these peels make them a powerhouse addition to your compost bin!

If you’ve been using a garbage disposal, you likely need more frequent service visits to ensure to continued and proper functioning of your septic system. Contact us today!

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