How Does a Septic Tank Work?

Septic systems are a type of sewage treatment method that uses a large tank – typically made from precast concrete or special types of reinforced plastic. Septic tanks work by taking the wastewater from a property and treating it inside the tank – before pumping out the treated waste via an outlet pipe.

There are a few different variations, but the essential principles of a septic tank sewage treatment system are as follows:

  1. Wastewater (effluent water) and solid waste enters the tank from a house
  2. The waste naturally reacts and breaks down within the tank, allowing scum and slurry to separate from the water
  3. The treated liquid is pumped out, usually in a drain field or a waste tanker

Septic tanks typically have 1, 2 or 3 chambers. The tank is essentially a type of filter and most designs look similar to below.

As leading providers of a wide range of plumbing services, including the maintenance and installation of many kinds of septic tanks, we are well-placed to explain how they work in more detail. We offer excellent rates for all sorts of high-quality plumbing work in the southeast of the UK with no call out charges.You will see our first-class team are ready to spring into action whenever you need – simply get in touch with us for a free quote. We will now explore a little bit more about different types of septic tanks and how they work.

How 2 Chamber Systems Work, Benefits and Drawbacks

A 2 chamber septic tank system is more than enough to handle human waste, oils and grease or other wastewater contents. The first chamber works like a container, handling the waste and allowing scum and sludge to settle within it.

Various aerobic and anaerobic processes will take place in the chamber, allowing the solid waste and the dirty water to separate. The water is then pumped into the second chamber, where an effluent pump disperses it after filtering.

The main benefits of a 2 chamber septic tank system include the following:

  • Cost-effective
  • Small size
  • Suitable for rural areas

Although they offer more effective treatment for sewage than a single chamber, there are a couple of drawbacks to 2 chamber systems – including the following:

  • Less room for sewage than 3 chamber designs, which may not be suitable for some properties
  • Smaller sizes can mean more frequent pumping and cleaning is necessary

Draining a 2 chamber septic tank is not as frequent as a single chamber design – but this could change depending on the level of use. 

How 3 Chamber Systems Work, Benefits and Drawbacks

3 Chamber Septic Tank Installation

How does a septic tank work? Very efficiently if you use a 3 chamber design. 3 chambers in your system give you extra filtration – but the principle of the septic tank design remains the same no matter how many chambers you have.

As the chambers in the tank fill with waste, they will drain into the next chambers and ultimately the drainage pipe. With 3 chambers you will have a bit more time for the scum and sludge to settle meaning you get cleaner wastewater in the end.

The main benefits of a 3 chamber septic tank system include the following:

  • Capable of handling large volumes of waste
  • Better filtration and a higher breakdown of fat, grease, sludge and slurry
  • Less chance of a system failure, and consequent groundwater pollution

Although they are excellent at what they do, 3 chamber septic tank designs come with the following drawbacks:

  • Cost, large systems can be very financially cumbersome to install
  • Maintenance, more chambers means there is a higher chance that the system will go wrong so extra maintenance is often necessary

3 chamber septic tank designs will offer the best outcomes in terms of filtration, but their large size, high cost and complex design can make them a less desirable option.

How Often Should a Septic Tank be Emptied?

Blocked drain in Brighton quick response by local experts from Blockbusters

An age-old question that has plagued drainage experts is precisely how long a septic tank requires emptying. It is different for every situation, but the good news is that it will not be very often at all – emptying every 1 to 3 years is normal.

However, the frequency of emptying depends largely on usage. As a result, it could easily be more or less frequent. If you have a large number of people in your household then emptying may be an annual event – but it could be up to 10 years.

Free Upgrades for Septic Tanks

Problem with your septic tank? Get it upgraded to a sewage treatment system – all for free! It’s covered by insurers and can save you thousands, so contact us to find out more.

What Are the Signs That a Septic Tank is Full?

Although your system might rely on a drainage field there are some signs your tank is full and requires emptying. Although there may be signs from your tank by itself there are other indicators inside the house, such as the following:

  • Bad flush: A major sign that a septic tank needs emptying is the presence of a bad or poorly functioning flush in your toilet. Any type of slowed drainage is a sign that you should check your tank.
  • Overflow: A septic tank may fill up and simply spill out into the ground. Checking the area around your tank for the presence of any moisture, checking if there is an unpleasant smell too, is a big sign the tank is full.

If a septic tank is nearly full or overflowing then you may also find that your grass is much lusher, thanks to the nutrient-rich water, so you should take this as a sign warning too. Other indications include loudly gurgling pipes and drain splutters. 

Does Shower Water Go Into the Septic Tank?


Yes, normally. The vast majority of modern septic tank systems will pass the water from a washing machine, shower or any other drain through them. The kitchen sink, laundry water and any other wastewater are filtered by the system. This is a good thing! If you do not have enough water in the system this can affect soil absorption. As a result, the more water that passes through (especially relatively clean water like kitchen or bath water) the more smoothly your system will run in the long term.

Get a Septic Tank Installation Expert

A septic tank is a type of mini sewage treatment plant. The tanks work by filtering the waste from a property and pumping it out. You might require just 1 chamber, but 2 chamber and 3 chamber designs are increasingly common.

Unlike other providers, we do not give you any kind of call out charges. Please feel free to get in touch with us to install a new septic tank system or for any ongoing maintenance. Our team is ready to serve you all over the southeast of the UK.

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