Yeast for Septic Tanks: A Brilliant Life Hack or a Total Hoax?

Is Yeast A Brilliant Life Hack or a Total Hoax?

If you own a septic system you have most likely heard from a neighbor, parent/grandparent or perhaps even an old DIY blog: “Just flush a packet of yeast once a month and you’ll never have to pump your tank.” The use of yeast for a septic tank was once a popular home remedy and has been an old “secret” passed down from generation to generation. While yeast is a living organism, a septic tank is not a loaf of bread and yeast in septic tanks can actually do more harm than good in your septic system. When asking is yeast good for septic tanks it is important to understand that while yeast eats sugar/starch, it does not eat the fats, oils, and proteins that make up the bulk of septic sludge. 

How Does Yeast Work in a Septic Tank?

Many homeowners find themselves asking, does yeast help septic tanks? It is important to remember when asking should you put yeast in your septic tank that yeast is not a replacement for good bacteria which typically already exists in a healthy septic system. When using yeast for septic tank maintenance you must realize that although septic tanks need bacteria to function properly not just any bacteria will do. Anaerobic bacteria must be present in order to successfully digest solid waste. The University of Minnesota (Care and maintenance | Onsite Sewage Treatment Program) provides care and maintenance tips for septic systems without the use of yeast and focuses on how to protect and maintain the good bacteria that is already in the tank.

Why the “Yeast Life Hack” went Viral

Baker’s yeast in septic tank also known as dry yeast for septic system became a common home remedy in the mid-20th century before modern enzymatic treatments existed. This was due to yeast being cheap, organic, and easily accessible. Yeast for septic tank maintenance became the original DIY solution due to the belief that it can help jump-start bacterial growth due to being a living organism.  Unfortunately, yeast is a fungus that feeds on simple carbohydrates such as sugars and starches which are scarce in septic systems. Without the proper food source yeast cannot multiple. 

Can You Put Too Much Yeast in a Septic Tank?

If you have already decided you wanted to try yeast the next question you may ask is can you put too much yeast in a septic tank? Too much yeast causes excessive gas production and can even be counterproductive. This can agitate the “scum layer”, causing solids to bypass the baffle and head straight for the drain field. Once in the drain field clogs and system failure may take place. Yeast fermentation also produces alcohol, which in high enough concentrations can actually inhibit the growth of the beneficial bacteria you want in your tank. When yeast thrives too well, it can create a thick, frothy mass that clogs inlet pipes. 

Yeast for Septic Tank vs Professional Bacteria Treatments

What Real Septic Professionals Say About Yeast in Septic Systems

Does yeast help septic tanks – the professional consensus is “no”. Most plumbers and septic professionals can agree that when yeast is used in tanks this results in “yeast heavy” tanks which tend to have clogged baffles and prematurely failed leach fields. When questioning how to care for your septic system it is best to bypass the old wise tale and listen to the EPA (How to Care for Your Septic System | US EPA) and the Clemson Cooperative Extension (Be Septic Safe: Best Practices for Septic System Maintenance | Home & Garden Information Center) who both agree that proper maintenance is far more effective. The EPA confirms that “septic system maintenance is not complicated, and it does not need to be expensive. Upkeep comes down to four key elements: inspect and pump frequently, use water efficiently, properly dispose of waste, and maintain our drain field. When these four elements are put into practice, yeast and others additives should not be needed. The natural bacteria from household waste is sufficient enough to keep a septic system bacterial levels balanced. 

Better Alternatives for a Healthy Septic Ecosystem

1. Human Waste. This is the best bacteria you can flush directly into your septic tanks. Best of all – it is free!
2. Enzymatic Additives. There are products on the market that are specifically designed and engineered to eat “FOG” (fats, oils and grease). 
3. Avoiding “The Killers”. By being cautious of what you put down your drains such as not using Drano, excessive bleach or cleaning products is fair more effective than adding yeast.

Frequently Asked Questions About Yeast and Septic Care

How much yeast do you put in a septic tank?

Although not recommended, if you still choose to do so most “old recipes” suggest ¼ cup. Again, this is not recommended due to the risks associated with it and the potential harmful effects. The use of yeast is now considered unnecessary and even counterproductive for septic systems.

Does yeast dissolve toilet paper?

The simple answer is no. Yeast does not contain the cellulase enzyme required to break down paper. Since yeast is used for fermentation it does not assist in the breakdown of toilet paper or other fats, oils or proteins. Studies have shown that yeast does not improve digestion or reduce buildup. In fact, it can even disrupt the natural bacterial balance and prevent the breakdown of toilet paper. 

Can I use expired yeast?

It will not hurt the tank, but it also will not do anything either. 

How often should I put yeast in my septic tank?

While some DIY sites suggest once a month, experts advise against it entirely due to the risk of sludge agitation. Healthy septic systems do not need yeast or any other additives on a regular basis. 

Does raw meat or rotten tomatoes help a septic tank?

Again, this is another common myth that we see used. Like yeast, these introduce organic matter that requires digestion rather than providing the specific bacteria needed for tank health. It is best not to put rotten meat or any other rotten matter directly into your septic tank. 

Will yeast stop a septic tank from smelling?

Usually no. Odors are caused by gasses like hydrogen sulfide. Yeast fermentation actually produces more gas, which can cause exacerbate odor issues. If your septic system is omitting an odor it is best to look at potential causes and solutions recommended by a septic professional.