Can I Have a Garbage Disposal With a Septic Tank?

Last Updated:  November 3, 2020

should i use a garbage disposal with septic systemIf you are coming from a more urban environment, where your pipes lead to a sewer system instead of a septic tank, you may think of a garbage disposal as a convenient appliance. You may think using one is a minor imposition on the system or no imposition at all. Or you may just not have thought about it at all.

But you need to understand that septic systems work differently from city sewer systems. Living with a septic system is a bit like moving to a foreign country. It’s a whole new culture, so to speak.

A septic system needs to be handled differently from a sewer system in terms of what you put into it and how you interact with it. Those differences in handling occur primarily in the form of modifying your day-to-day behavior at home.

You mostly won’t be interacting directly with the septic system. In fact, you want to interact with it directly as little as possible.

Instead, you will be interacting indirectly with it. But you need to understand that when you interact directly with household items like the toilet or disposal, you are interacting indirectly with the septic system.

You need to think about how you are impacting that system. ‘Out of sight, out of mind’ is a dangerous position in this case. It can lead to serious problems.

Convenience Costs

Let’s say you are peeling potatoes and historically you would have put those peels down the disposal. Now you are in a home with a septic system and wondering what to do.

Maybe you feel it’s a small thing and your other options are less convenient in the here and now. It seems like more hassle to put them in the trash can or start a composting heap.

Think again. That short term convenient answer can have substantial costs in terms of time, money and hassle.

Putting large quantities of food down the disposal when you have a septic tank can lead to increased clogs, the need to pump the tank more frequently and the risk that the tank will need to be dug up. If you think starting a composting pile is too much hassle, do you really want to spend additional time, money and energy scheduling septic tank maintenance and waiting around for a plumber? Can you even afford to take that many days off from work?

Why It Matters

Septic tanks are designed to handle human waste, not kitchen waste. Feces and urine are already broken down to some degree. Food waste from the kitchen is not.

Septic systems are already typically in a delicate state of health that is easily upset. There are lots of harsh chemicals you shouldn’t be putting down your sink or toilet because they can kill the microbes in the system that are breaking down wastes. Adding “foreign” matter that the system wasn’t designed to handle just makes this problem worse.

The system was simply not designed to deal with food waste. It’s as simple as that.

When you put food waste into the system, especially in large quantities, it changes the chemical and microbial environment. This actively interferes with the system’s ability to do its job.

Microbes are essential to the process of breaking down waste. Disrupting the microbial system causes the system to stop working.

Food wastes also tend to cause clogs in the system. This is especially true for some foods, such as fats and grease and foods that expand in water, such as rice and noodles.

Best Practices

In order to understand how to deal with a disposal when you have a septic system, you should understand how the system works generally. It will be easier to understand what you should and shouldn’t do if you have some larger context.

Let’s go over a little of that now, along with talking about some general best practices. Seeing what you shouldn’t do generally may help you better understand the restrictions on disposal use.

A septic system involves a holding tank and a leach field. No, it is not intended to be a permanent, maintenance-free solution. Although you need to be mindful of the chemical and microbial balance, it doesn’t simply break everything down completely where you can forget the tank even exists.

It needs to be inspected annually and pumped out about every three to five years. The more use of your system, the more your tank needs to be pumped out.

So as your family grows or if you start throwing more parties or otherwise having more people in the house, this will put a higher load on the system. If you misuse your system, this will also cause problems.

There are actually lots of videos on the topic of how a septic tank works. Here’s a nice illustrated video to get you started:

There are different kinds of designs. You should know which one you have and how it works. Here is a good overview of single compartment, double compartment and pump systems from the King County, Washington government.

Don’t put anything down the toilet other than toilet paper and bodily wastes. Do not flush household cleaners, diapers, tampons, condoms, cigarette butts, unwanted medication, oil or grease or any number of other things that people commonly put down toilets.

Be water wise. Running too much water through the system is a common cause of or factor in septic tank failure.

Be mindful of not negatively impacting the tank physically. This includes both landscaping choices and lifestyle choices.

You don’t want to use plants with deep roots that can invade the tank. You don’t want to park a car above the tank. It will impact the soil and can potentially break pipes.

Dos and Don’ts For Your Disposal

The gold standard rule of thumb is simply don’t use a disposal at all with a septic system. However, that may not be the most realistic expectation.

Maybe you moved into a house that already has a garbage disposal and a septic system. Maybe you have some reason why you feel you need to add one.

So let’s go over some other dos and don’ts. Hopefully, that will minimize problems if you do have a disposal in the house and a septic system out back.

So, should I Use a Garbage Disposal with a Septic System?

The best advice you can get is to just not use a garbage disposal with a septic system. The second best advice you can get is to use it minimally and responsibly.

If you have bought a house with a septic system and it doesn’t already have a disposal, don’t add one. It’s much easier to find other solutions if turning on the disposal is simply not an option.

In fact, if you have bought a house with a septic system and it has a disposal, you should consider having it removed. If you do so, get it removed by a professional plumber who can replace it with the appropriate pipes.

Yes, that’s counter-intuitive for most people. People typically don’t like giving things up. But it can’t be more expense or hassle than having your septic system pumped more frequently or having your septic system fail.

If you are renting a home and can’t remove the garbage disposal, then use it minimally. Generally speaking, the less you use it, the better.

If you are on good terms with your landlord, you might ask if they would remove the disposal.

Perhaps you can educate them as to why this is the cheap, logical solution by sending them articles like this one or just talking with them about the issue.

Humans are creatures of habit and will tend to do what they have always done. It can be hard to get them to change their habits. Renters are notoriously bad about not knowing how to take proper care of the property. Some folks simply don’t care.

The bottom line is that garbage disposals and septic systems simply don’t play well together. It makes more sense to simply not pair them up in the same home, even if that means removing the existing garbage disposal, though it works just fine.