What Is a Septic Tank and How Does it Work?
Septic tanks are essential components of wastewater management systems, particularly in rural areas where access to mains sewerage is unavailable. These watertight underground chambers collect wastewater from sinks, washing machines, toilets, and showers, preventing it from contaminating the environment.
What is a septic tank?
A septic tank separates solids from liquids in the wastewater. As the wastewater flows into the tank, solids settle at the bottom to form sludge, while lighter substances like fats and oils float to the top, forming a layer known as the crust. The clearer liquid in the middle is then directed to a soakaway system or drainage field, where it is safely dispersed into the ground.
At Universal Tankers, we provide specialist septic tank emptying services to domestic and commercial clients across the UK. Our team ensures that your septic system operates smoothly. We also offer a convenient reminder service, so you never have to worry about missing a crucial maintenance schedule. In the following guide, we explain everything you need to know about septic tanks, including how to maintain them.
Why are Septic Tanks Used?
Septic tanks are commonly used when there is no access to mains sewerage so wastewater can be safely collected, contained, and disposed of when necessary. This is often in rural locations where access to mains sewers is not even an option.
Septic tanks collect all liquid produced from a property or collection of properties. With there being no connection to a wider network of drainage, it is a necessity for septic tanks to be emptied on a regular basis.
The Types of Septic Tank Systems
In the UK, there are two main types of septic tanks, each with its unique design and benefits. Both require regular maintenance, including emptying and inspection, which is vital to prevent issues like slow drainage, water pooling, and sewer backups.
Brick-Built Septic Tanks
Brick-built septic tanks are the traditional type of septic tank but are still just as effective as more modern glass-reinforced tanks.
A brick-built septic tank usually uses two main chambers. These tanks are usually constructed with an inlet pipe on one side and an outlet pipe on the other. These will be either T-pipes or dip pipes depending on the age of the tank. Once the wastewater fills the first chamber, the second then fills with the surplus volume. The wastewater is then released out of the outlet pipe into either a soakaway or drainage field.
Glass Reinforced Plastic Septic Tanks
Also known as onion septic tanks, GRP tanks work in a similar way to brick-built septic tanks. Despite differences in design, the principles of how these work remain the same. Their main key difference is that GRP tanks contain a fitting at the top of the septic tank called a buffer. This prevents the backflow of solids and fats back into the drainage pipe and instead acts as a sieve to hold onto the solids.
How Does a Septic Tank Work?
Despite what the name may suggest, septic tanks do not actually provide wastewater or sewage treatment, but instead aid in the separation of solids and liquids. After wastewater has entered a septic tank, it is separated into one of three areas (these areas can also be known as layers or zones):
- Top layer: this is where the least dense matter settles. Waste such as fats, oil and grease (FOG waste) sit here as they have not yet broken down. The top layer is often referred to as the 'crust'.
- Middle layer: the middle layer is the least viscous section of a septic tank. When the waste flowing into the tank has been broken down and solids separated, what is left is the free-flowing waste that settles in this section of the tank. As a result, this section contains the wastewater without any remaining solids. It is from the middle layer of the septic tank that the wastewater leaves and flows into the soakaway system or drainage field (more on this later).
- Bottom layer: the bottom layer is where the most dense waste settles. Matter known as sludge sinks to the bottom of the tank over time. This is the matter (along with the crust) that needs to be removed regularly from the tank for it to keep functioning without issues.
When the septic tank becomes full, it must be emptied safely - meaning in a way that does not compromise the environment. There are a few ways in which this can be done:
Soakaway System
A soakaway is a common drainage system used to disperse water from a septic tank into the surrounding area. A regular soakaway consists of a hole dug into the ground filled with a combination of coarse stone, rubble and plastic crates. Having the hole filled with these materials makes a soakaway the perfect holding area for large volumes of liquid, giving adequate time for the liquid to disperse into the surrounding ground.
Soakaway systems are highly effective at allowing the flow of liquid out of a septic tank, whilst also ensuring the surrounding ground does not get overly saturated with large volumes of water.
Drainage Field
Similar to a soakaway, a drainage field serves a similar function to a septic tank. A drainage field allows water from the septic tank to drain via perforated pipework, into the ground surrounding the pipe.
This managed flow of liquid allows for consistent dispersion of water into the adjacent subsoils. This prevents the ground surrounding a septic tank from getting oversaturated whilst ensuring the septic tank drains a sufficient volume of liquid allowing it to function and work effectively.
Wastewater Services
While the previous two methods are generally safe, the most secure way to empty a septic tank is to transfer the septic tank effluent to a sewage treatment plant so it can be processed before being disposed of. At Universal Tankers, we collect wastewater using our fleet of tankers and transport it so you do not have to worry about the hazards involved with emptying it through a soakaway or drainage field.
How Often Do I Need to Empty My Septic Tank?
As a general rule, septic tanks should be emptied annually. However as previously mentioned, this is entirely dependent on the size of the tank and the amount of waste going into it. Our wastewater experts can advise you on this.
Here are some signs that your septic tank may be full and requires emptying:
- Water pooling: when a septic tank is full, excess water can flow over into the nearby drainage areas.
- Slow drainage: this could also be a sign of a blockage in the drainage system.
- Excessive odours: as the dense sludge starts to fill a tank, the smell of the waste can start to escape the tank.
- Sewer backup: when a septic tank is full and there is no space in the tank, waste no longer has anywhere to go, so will back up the drainage system and eventually back into the property. This is one of the most unpleasant ways to find out your septic tank needs servicing and can result in a costly repair bill. When this happens, the drains nearest to the tank will be the first to show signs of backup. If sewer backup occurs, have your septic tank emptied immediately.
What Are My Legal Obligations for Maintaining and Emptying a Septic Tank?
Maintaining and emptying a septic tank system goes beyond efficient operation - it is also an environmental legal requirement. In the UK, the maintenance and emptying of septic tanks are governed by various regulations, such as The Environment Agency, Building Regulations, and local council bylaws.
Septic tanks should be inspected regularly by qualified professionals to check for any issues, and all inspections, pumping activities, and repairs must be recorded.
Any leaks, overflows, or system failures must be reported to the relevant authorities immediately to mitigate environmental damage.
Failing to meet legal obligations can result in significant penalties:
- Fines and legal action: the severity of the penalties depends on the extent of the violation.
- Environmental damage liability: you could be held liable for cleanup costs and additional fines.
Our Septic Tank Services
Universal Tankers can empty your septic tank to ensure you comply with your legal requirements and that your waste does not get backed up. We offer septic tank emptying services to domestic and commercial clients. We also offer a regular reminder service should you require this service to make sure you never get any of the signs of a full septic tank discussed previously.
For more information, simply get in touch with our team today by calling 0800 180 4474 (England) or 01236 434422 (Scotland), or fill out an online contact form and we will be in touch at a time suitable for you.
