Septic Tank Additives: Which Ones Work Best?
Some homeowners opt to use septic tank additives, hoping that these additives will keep their system running efficiently and extend the time between pump-outs, as well as extend the life of their septic system. Others may purchase additives hoping to save a failing system.
Should I use any septic tank additives to make it work better?
Common Septic Tank Additives Compared
Let’s take a quick look at a few of these septic tank additives:
Calcium
Calcium can be used to raise the pH level in your septic system in order to increase the function of the good bacteria that breaks down your sewage. However, too much calcium can negatively impact the pH level in your system and end up killing off the good bacteria instead.
As well, too much calcium can as act as a flocculant (a substance that promotes clumping), which can prevent the solid waste from settling properly and lead to the premature clogging up of your septic field.
Baking Soda
There is no proof to suggest that baking soda (sodium bicarbonate) can improve the rate of flocculation in your septic system.
To see any change in flocculation in your septic system, a huge amount of baking soda would need to be added, and that could, in turn, upset the chemistry of your septic system (for example, the pH) and negatively impact the existing bacterial communities that are essential to a healthy, properly functioning system.
Yeast
The bacterial colonies that live in your septic system do not eat yeast and are not made up of yeast, so adding yeast does nothing to boost their efficiency. While you might think that yeast would be harmless to a septic system, that isn’t necessarily the case.
Yeast causes frothing and agitates the contents of the tank, which prevents the solids from settling to the bottom of the tank and fats from coagulating on the surface.
This results in solids escaping to the drain field, where they can clog soils and shorten the lifespan of the soil absorption system, and that can lead to the need for expensive repairs.
Bacteria
There are times when the natural bacterial communities living in your septic tank may be killed off by poor homeowner practices or may die off due to unavoidable circumstances.
Here are a few examples:
- Chemical treatment with drain cleaners, solvents, or antibacterial agents
- Heavy household use of antibacterial soaps/detergents/cleaning agents
- Extensive or prolonged use of antibiotics
- A cottage or vacation home that is vacant for six months or longer
While there are bacteria “starter” additives on the market that will replenish the bacterial communities in your septic tank and rejuvenate the system, these are not really needed if you care for your septic system properly. See more in our Septic System Care Guide: 37 Dos, Don’ts and Nevers.
Also, keep in mind that the addition of new wastewater effluent and sewage will dilute the contents of your septic tank over time and continue to reinoculate the system with bacteria.
Also, while the smaller quantities of bleach and drain cleaners that most households normally use are not likely to harm a healthy septic system, please keep in mind that it’s still better not to add these to your system at all.
Finally, keep in mind that if you don’t address and fix the cause of a bacteria die-off in your septic system, the underlying problem will persist.
The new bacteria will also be killed by whatever killed your initial bacterial community if it is still being added to the mix – no matter how much bacterial starter you throw into your tank.
As soon as you stop adding harmful chemicals, disinfectants and/or antibiotics to the system, the tank will be reinoculated with natural bacteria when human waste is flushed down the toilet. So, there really is no need to purchase a starter culture to add bacteria to the system in most cases.
Chemical Additives
Chemical additives are often used to clear clogged pipes or unclog a drain field, control odour problems, or act as degreasers.
Chemical additives include:
- hydrogen peroxide
- caustic soda (sodium hydroxide)
- sulphuric acid
- commercial drain cleaning products.
These are often used in septic systems to clear clogged pipes or to unclog a drain field.
However, these chemicals are extremely harsh and can actually damage the system rather than fix it. For example, hydrogen peroxide can agitate fine particles in clay and loam soils, disrupting the soil structure and reducing soil permeability.
Sulphuric acid, the key ingredient in many commercial septic system products, is extremely corrosive in its concentrated form and can not only negatively impact the bacterial colonies that are hard at work in the septic tank and drain field but can also weaken the structure of a concrete tank.
Commercial chemical products that are marketed to address odour problems typically contain formaldehyde, quaternary ammonium, and zinc sulphate as their active ingredients. They combat odour by controlling the growth of anaerobic bacterial communities, or more specifically, by targeting bacteria in the septic system.
Considering that these bacterial communities form the backbone of a healthy septic system, this is not just counterproductive, it is also extremely destructive. Use of these products can result in an unbalanced system that potentially does not function efficiently, or (in a worst-case scenario) could lead to complete system failure.
Dead Chicken / Roadkill / Raw Meat
An old wives’ tale which (thankfully) isn’t seen much anymore is that tossing a chicken carcass, roadkill, or even some raw meat into a septic tank will boost bacterial activity within the tank and improve the rate of digestion which, in turn, will reduce the need to have the septic tank pumped out.
The thinking behind this folklore is that adding a dead animal or some raw meat to the tank will add bacteria to the system or and/or provide a source of food to existing bacteria, which will then stimulate the growth of the bacterial colonies living within the system. The reality is that bacteria is added naturally when human waste enters the system, and that waste also provides all the food the bacteria colonies in your septic system need to survive.
Best Septic Tank Additives?
In summary, using septic tank additives will not compensate for a poorly designed system, regular system maintenance and inspection, or having your tank pumped out every 3-5 years (or as needed).
In fact, in some jurisdictions where the municipality has concerns regarding the impact on groundwater, building codes prohibit the use of septic tank additives, drain cleaners, degreasers, root killers, etc. all together.
There is no need to throw chemical or biological additives, raw meat, dead chickens or roadkill to stimulate digestion. Harsh chemicals such as sulphuric acid and caustic hydroxides should never be used in a septic system as they can kill the bacterial communities living within the tank, cause the soil in the drain field to become less permeable, and leach into the environment and contaminate groundwater sources.
If you have a well-designed septic system that is properly operated and maintained, bacteria will be added to the system naturally with the human waste that enters the system.
These naturally occurring bacteria get all the food and nutrients they require from the waste that’s in the tank. There is no need to add more bacteria, nor do you need to add anything to feed them or stimulate their activity.
By adding more bacteria without adding any additional waste, the bacteria will either die off as there will be insufficient food to sustain the artificially enlarged colony, or they may resort to feeding on each other. Either way, their numbers will die back to keep in the system in balance.
