No Such Thing as “Good” Grease for Your Septic System

No good Grease for Septic System

Most septic owners are aware that pouring down the drain meat drippings, butter, and other greases that congeal at room temperature is a bad idea. Even if they don’t know the effect these FOGs (Fats, Oils, Grease) have on their septic system, they know they can create nightmare clogs in their pipes. But what most septic owners don’t realize is that all greases—even those that remain liquid even below the freezing point of water—can wreak havoc on their septic systems. Read on to learn the pitfalls of flushing these FOGs into your septic system as well as to discover the best practices for keeping these greases out of your drains.

No good Grease for Septic System

Differences in Types of Grease

Generally speaking, the greases in our homes can be categorized as either solidifying or liquid. As you can probably guess, solidifying greases become solid at room temperate or colder. These include butter, high quality olive oil, shortening, non-fractionated coconut oil, etc. Liquid grease remains liquid even at very low temperatures. Vegetable oils, fractionated coconut oil, and baby oil are some of the most common of these.

Solidifying Greases

Solidifying grease are those that become solid (or semi-solid) at room temperature (76 degrees) down to the freezing point of water (32 degrees). Many people recognize the potential plumbing catastrophes that can result from pouring solidifying greases down the drain. Butter, hamburger grease (and any meat grease), and the like are generally known to cause problems for our plumbing. These greases can cause nasty clogs in the pipes underneath your sink as well as those much deeper in your home’s plumbing, including those leading into your septic tank. Once there, these solidifying greases can clog up your inlet and outlet baffles, which can lead to sewage backing up into your home or flowing out into the drainfield.

Many septic owners mistakenly believe that flushing hot water down the drain with these greases will prevent these problems. However, while the grease may stay liquid in the immediate plumbing underneath your sink, as soon as it hits cooler temperatures, that grease will separate from the greywater and cling to the walls of your pipes. Eventually, you’ll find yourself dealing with an epic plumbing and/or septic disaster.

Liquid Greases

Liquid greases are those that remain liquid even below the freezing point of water. Because they do not solidifying but for under extreme temperatures, most homeowners believe pouring these down the drain is okay. Though they may not cause clogs, these liquid greases can create significant problems for your septic system.

The wastewater within your septic tank separates into three, fairly distinct layers—sludge, scum, and effluent. The layer of sludge is composed of the solids that have settled to the bottom of your tank. A layer of “scum” floats at the top and made up of all the things that don’t sink, like fats, oils, and greases (FOGs). The effluent is the relatively “clear” gray water in between these two. The tank receives wastewater from your home through the inlet baffle. Effluent leaves your septic tank and flows out into your drainfield through the outlet baffle. While there is typically may be an effluent filter on the outlet baffle, the more FOGs a septic tank contains, the higher the likelihood that these or other solids will find their way out into the drainfield. As we’ve mentioned before, solids or FOGs in the drainfield can cause catastrophic system failure if the drainfield pipes become clogged.

Any grease—whether solidifying or liquid—will add to the FOGs within your tank, so it’s important to protect your septic system by limiting the amount of FOGs that find their way into your tank.

Unexpected Sources of Grease

One big aspect of keeping grease out of your septic system is in knowing how the grease finds its way to your septic system in the first place. Obviously, pouring cooking grease directly down the drain will flush FOGs into your septic system, but there are some less obvious sources that may contribute significantly to the layer of FOGs in your tank.

Garbage Disposals

When it comes to FOGs, most people already know the most common sources found in the kitchen. When we cook with grease, we know cleanup will involve somehow disposing of that grease. But one of the most surprising sources of FOGs in the kitchen is the garbage disposal. Typically, when we finish a meal, our gut instinct is to scrape our plates and dishes into the sink with the garbage disposal before flipping the switch that miraculously carries the after-dinner mess away. But these undigested foods not only contain their own natural oils but also the oils used during preparation. This is one significant reason we recommend against using a garbage disposal in a home that relies on a septic system.


While excellent for skin health, moisturizing toiletries are another common, though unexpected, source of grease. With names like body butter, oil, and cream it should come as no surprise that these toiletries contain FOGs. But most septic owners pay no mind to the potential greases found in their bath products. However, these products, especially when used in the bath or shower, deposit far less moisturize oil onto your skin than end up washing down the drain and into your septic system. Products high in coconut oil are particularly troublesome because coconut oil becomes solid at 74-76 degrees. Coconut oil in the ever-popular bath bombs, body butters, and moisturizing creams becomes solid pretty much the moment it leaves the tub.

Keeping FOGs Out of Your Septic System

Knowing the pitfalls of flushing grease, in any form, down the drain is the first step in keeping FOGs out of your septic system. Being aware will help you be mindful of where your grease goes.

Kitchen FOGs are some of the easiest to avoid. Drain cooking grease into a disposable container—glass jars or aluminum cans work well—before disposing of them in the garbage. Put food scraps into the garbage or compost bin (as appropriate) and wipe dishes with a paper towel to limit the amount of food grease that enters your septic system. If you have one, limit your use of the garbage disposal to only clearing whatever remnants may have been present after you wiped down the dishes and disposed of the scraps in the garbage.

Check the ingredients in your favorite body washes. Those high in oils — coconut oil, shea butter, etc. — will add to the layer of FOGs in your septic tank and possibly create nasty clogs in your pipes (especially if they’re mixed with hair). Use body and hand lotion rather than moisturizing body washes or hand soaps.

Keep Your Septic FOGs in Check with Routine Service Visits

Unfortunately, it’s impossible to completely prevent all FOGs from entering your septic system. By sticking to these best practices, you can greatly limit the amount of FOGs in your septic tank, but you’ll still need to have your septic system regularly serviced to ensure the layer of scum isn’t getting out of hand in your septic tank. With more than 52 years serving as Northeast Ohio’s most trusted septic provider, Supeck Septic is happy to provide routine or emergency septic care. Contact us today to schedule your next service visit!

Related Articles

Disposing of Fats, Oils, and Greases (FOGs) in Your Home

Are Bath Bombs Septic-Safe?

Garbage Disposals and Your Septic System