Should I Add Bacterial Additives or “Boosters” to My Septic Tank?

What Are Bacterial Additives or Boosters?

Bacterial additives, sometimes called septic tank boosters, are products designed to increase or replace the naturally occurring bacteria within a septic system. They typically come in packets, powders, tablets or liquid solutions and are usually poured down the toilet or directly into the septic tank. The idea behind them is that they add beneficial bacteria or enzymes that break down waste more effectively.

Manufacturers often claim that these products help reduce solids within the tank, improve drainage, eliminate odours and sometimes even reduce the frequency of emptying. Some people use them believing they are essential for the health of their system, while others remain sceptical. Understanding their purpose is the first step to deciding whether they are necessary.

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How Does a Septic Tank Work Naturally Without Additives?

A septic tank is a self-contained wastewater treatment system that relies on natural processes. When wastewater from toilets, sinks and showers enters the tank, it separates into three layers. Solid waste settles at the bottom to form sludge, fats and oils float to the top to form scum, and the liquid between these two layers is called effluent. This effluent slowly flows out into a soakaway or drainage field, where it is filtered naturally through the soil.

The most important part of this process is the naturally occurring bacteria already present in human waste. These bacteria start breaking down solids as soon as they enter the tank. They do not need to be added because they already exist in the waste itself. As long as the system is used regularly and not overloaded with harsh chemicals, healthy bacteria will continue to thrive and keep the tank functioning efficiently.

This means that under normal conditions, septic tanks are designed to run without any form of additive. Regular use, proper maintenance and periodic emptying are usually all that is required.

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Do Septic Tanks Really Need Bacterial Additives?

In most working septic systems, bacterial additives are not necessary. A well-maintained tank with regular usage will naturally maintain its own bacterial balance, making additional boosters unnecessary. The bacteria responsible for breaking down waste already enter through everyday use of toilets and drains.

However, there are a few specific situations in which bacteria levels can become disrupted. For example, if a tank has just been installed, has not been used for a long period of time, or has been exposed to high levels of disinfectants, bleach or antibiotics, the natural bacteria may be reduced. In these circumstances, an additive might help reintroduce or boost bacterial populations.

Even so, it is important to remember that additives cannot fix serious problems. If a septic tank is damaged, overflowing, blocked or if the soakaway has failed, no amount of bacteria will resolve the issue. These problems require professional assessment and repair.

Advantages and Disadvantages of Using Additives

Some homeowners choose to use additives for peace of mind, and in certain cases, they may offer small benefits. For example, after a tank has been emptied, an additive might help to re-establish bacteria more quickly. They may also offer slight improvements in odour control in systems that are used very little.

However, there are disadvantages. Relying on additives can sometimes lead people to believe they no longer need regular emptying or inspections, which can result in bigger problems later. Certain chemical additives can even damage the delicate balance inside the tank or harm the soakaway. It is also worth noting that many claims made by some manufacturers are not supported by evidence.

A well-maintained tank that is emptied when needed does not require additional bacteria, and using additives should never replace proper care, inspections or professional advice.

Myths and Facts About Septic Tank Bacteria

One of the biggest myths is that adding bacteria means the tank will never need emptying again. This is false. Sludge still builds up over time because not everything can be broken down by bacteria, and this sludge must be physically removed.

Another common misconception is that septic tanks lose all their bacteria and need constant topping up. In reality, unless harmful chemicals or antibiotics are used in high quantities, most tanks maintain a stable bacterial environment by themselves.

Some people believe bad smells always mean a lack of bacteria and that additives will solve it. In truth, odours can be caused by a blocked vent, a full tank or a drainage issue, none of which can be fixed by bacteria.

Chemical-based additives are also sometimes marketed as safe, but in some cases, they can damage essential parts of the system or pollute the surrounding soil.

When Additives Might Help and When They Should Be Avoided

Additives can be useful in specific situations. If a property has been unoccupied for a long time and the septic tank has not been used, natural bacteria levels may have dropped and a booster could help reintroduce bacterial activity. They can also be beneficial after a tank has been professionally emptied or after a period of heavy cleaning chemical use where bacteria may have been killed.

They should be avoided in systems with structural issues such as cracks, leaks or collapsed soakaways. They are also not recommended when tanks are overflowing or when there are drainage issues. Using additives in these cases can delay proper treatment and potentially make things worse.

Additives should never be considered as an alternative to routine emptying or maintenance. They are optional, not essential.

Expert Advice from Pro Septic Tanks

At Pro Septic Tanks, we believe in honest, practical advice. In our professional experience, most septic tanks do not require bacterial additives to work effectively. The focus should instead be on proper system care. This includes routine emptying, avoiding flushing items such as wipes, fats and chemicals, and ensuring the soakaway is not driven over or flooded.

We recommend that tanks be emptied every twelve to thirty-six months depending on household size and usage. For holiday cottages, rental properties and commercial sites, this might need to be more frequent.

Additives can be used if a customer wishes to, especially after emptying or long-term disuse, but they should only be biological and never chemical. They are a supplement, not a solution to bigger problems.

Pro Septic Tanks provides inspections, installations, maintenance and full system replacements across Dorset, the surrounding counties and nationwide.

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Frequently Asked Questions

Do septic tanks naturally contain bacteria?
Yes. Human waste naturally contains bacteria that break down solids. As long as the tank is used regularly and not flooded with chemicals, it will maintain healthy bacterial levels on its own.

Can additives fix a failing or overflowing tank?
No. If a septic tank is overflowing, backing up or if the soakaway has failed, additives will not solve the issue. Professional emptying, repair or replacement may be required.

Are septic tank boosters safe for the environment?
Biological additives are usually safe, but chemical-based ones can cause harm to the system and environment. Always choose a natural biological product if you decide to use one.

How often should a septic tank be emptied in the UK?
Most households should arrange emptying every one to three years, although larger households or properties with high water use may need it more often.

What harms the bacteria in septic tanks?
Excessive use of bleach, disinfectants, antibacterial cleaners, paint, solvents and certain medications like antibiotics can reduce or kill bacteria inside the tank.

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