Can you have a garbage disposal with a septic tank?

Rather than putting food scraps into the trash, many homeowners put them into garbage disposals mounted under their kitchen sinks. These systems collect waste and then shred it into tiny pieces that are washed down the drain.

The technology works well enough in communities with municipal sewer systems. But is it wise to install a garbage disposal if you own a home with a septic system?

Based on our decades of experience in the wastewater treatment industry, the simple answer is no. We recommend that you avoid using a garbage disposal with a septic system for several reasons.

Table of contents

1.	Reduction in septic system performance
2.	Additional expenses
3.	Alternatives to garbage disposals
4.	Tips for using garbage disposals (if you must)

Garbage disposals reduce the effectiveness of your septic system

Wastewater solids that sink to the bottom of your septic tank are called sludge. In healthy tanks, bacteria have enough time to break down organic matter and keep sludge levels in check.

You overwhelm these bacteria if you continually put pieces of food down a garbage disposal. When this happens:

sludge levels rise
the capacity of your tank decreases
bacteria have less ability to treat your wastewater

Simple two-dimensional diagram of sludge levels rising in a residential septic tank.

Garbage disposals create additional expenses

If the bacteria in your septic tank do not have enough time to break down food particles, sludge levels are sure to rise. That means your tank will need to be pumped more frequently — up to twice as often according to some estimates.

The average price to pump a septic tank in the United States is about $400. For most homeowners, the advantages of garbage disposals seem small compared to the cost of additional pump-outs that could otherwise be avoided.

There are greener ways to dispose of food waste

Garbage disposals do not solve the problem of food waste — they merely deflect it.

Composting is a more environmentally responsible approach. It transforms organic waste into a sustainable and natural resource that adds nutrients to lawns, gardens, and flowerbeds.

This strategy is so simple that anyone can make it work. All you need is a compost bin or compost pile, a bit of know-how, and a place to spread the finished material.

The beauty of compost is that it has practical uses for gardeners and non-gardeners alike. With it, you can:

fertilize lawns and gardens
make potting soil for indoor plants
create moisture-holding mulch
help a neighbor who has a green thumb
support your local community garden

Vegetables, fruits, and other food waste in a wooden compost bin located in a back yard with green grass.

Tips for using a garbage disposal with a septic system

We know not everyone will follow our advice about garbage disposals and septic tank systems. If you choose to use a garbage disposal, here are a few tips to help you avoid problems.

What can you put in a garbage disposal?

Garbage disposals are designed to dispose of soft foods and non-dairy liquids. The following items are safe:

fruit flesh
soft and non-fibrous vegetables
cooked meat
ice cubes
biodegradable dish soaps

Vegetable peels and other food scraps being flushed down an Insinkerator Evolution garbage disposal system.

What not to put in a garbage disposal with a septic tank

Garbage disposals are designed for easily biodegradable food scraps. They are not equipped to cope with:

fruit pits and peels
stringy or tough-skinned vegetables (especially celery, corn husks, and artichokes)
onion skins
eggshells
pasta, rice, and oats (they expand in water and can clog your pipes)
nuts
bones
coffee grounds
potting soil
fats, oils, and greases (including dairy)
non-food items like plastic, paper towels, and twist ties

Remember: Even if these items pass through your garbage disposal, they will not break down inside your septic tank. Instead, they will accumulate until a pumper removes them.

Hot or cold water with a garbage disposal?

Food waste is more likely to get stuck in your garbage disposal or septic pipes if it is warm. Avoid clogs by running a steady stream of cold water just before and while you grind food in your system.

Regular maintenance is critical

Take care of your garbage disposal by maintaining it according to the manufacturer’s instructions.

Preventive action is also the best strategy for your septic system. Have a professional regularly inspect your installation and measure the sludge in your septic tank. If it is time for a pump-out, book your appointment as soon as possible to avoid system failures.

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