Septic Tank Installation

Cesspit vs Septic Tank - What's The Difference?

If you’re in need of a sewage solution on your property, you may be considering a cesspit or septic tank but confused as to what the difference between the two systems is. To help you ascertain whether a cesspit or a septic tank would be best for your needs, we have put together this ‘Cesspit vs Septic Tank’ guide, highlighting the major differences between the two and summarising their respective pros and cons.

Different properties are suited to different wastewater solutions so we hope this guide will point you in the right direction in terms of choosing a septic tank or a cesspit that will service the requirements of your property.

First, let’s define the two terms and what they mean…

Definition of a Cesspit

A cesspit, also known as a cesspool, is a sealed underground holding tank or pit into which sewage, waste water and other refuse is flowed, collected and stored. Cesspits are typically used in areas without access to a public sewer system. They are only designed to hold waste temporarily and can fill up quickly, requiring regular emptying, cleaning and other maintenance.

Definition of a Septic Tank

Similarly, a septic tank is a chamber or tank buried underground used for the treatment and collection of wastewater from homes or businesses without access to the mains sewer system. A septic tank separates solids from liquids, allowing anaerobic bacteria to break down the waste. The liquid effluent created as a result of the bacteria is then discharged to a drain field for further treatment.

Key Differences Between Cesspits and Septic Tanks

Now we have defined what each sewage system is, we can help you work out which is best for you – cesspit or septic tank? Let’s discuss the key differences, split into five areas.

Design and Function

From the outside, septic tanks and cesspit tanks actually look quite alike, comprising a large cylindrical tank with an in-flow tube to the top where the refuse flows in. But while the design is similar, the function of the two is different. Yes, they are both holding tanks for wastewater and sewage, but a key difference is that a septic tank is split into two interior chambers and partially treats the wastewater as opposed to simply storing it. The waste inside a septic tank system is then flowed out into a drainage system, often a field. So in simple terms, a septic tank treats the waste, a cesspit does not.


Both septic tanks and cesspits require servicing, but the regularity of the maintenance is a big difference between the two sewage systems. As a cesspit only stores waste, regular maintenance is essential and the tank must be emptied regularly, with most cesspits typically emptied monthly on average. This is vitally important in ensuring the tank does not overflow and continues to serve the waste needs of the property.

In contrast, septic tanks need less servicing as the liquid waste is discharged through the outlet pipe into the surrounding soil or drainage field. That said, a septic tank does still require emptying, desludging and cleaning every few years to remove any built-up solid waste and ensure the septic system functions properly.

Environmental Impact

The environment is another key consideration when deciding what type of sewage treatment system you should install on a property and there are significant differences between the potential environmental impact of cesspits and septic tanks. The nature of cesspits makes them more susceptible to environment issues, especially when not properly maintained. There is a much higher risk of overflow and environmental contamination with a cesspit so you must always have a licensed waste disposal company like Owls Hall on hand to empty and dispose of your waste.

With septic tanks, there’s less danger of environmental issues. As the tank itself partially treats the waste and produces treated wastewater safe enough to expel into the surrounding environment, there is a reduced chance of contamination. The fact that less waste is able to build up inside also limits the chance of overlow.


Cost is, of course, another key factor in the decision-making process. You need to consider both the short and long-term costs of septic tanks and cesspits. On the face of it, choosing a cesspit may seem the cheaper option as installation and purchase costs are lower. But you need to include future servicing and maintenance costs into your overall budget and maintaining a cesspit is undoubtedly more expensive than a septic tank. Your cesspit will have to be emptied several times throughout a year, while a septic tank requires only infrequent desludging and cleaning, significantly reducing running costs.

Usage Suitability

The final consideration is the type of property you own and how often it is used. For instance, if you own holiday homes or static caravans which are used periodically by guests, a cesspit is a good option. You’ll be able to get the waste removed from the holding tank and dealt with by a waste disposal contractor when necessary, which is likely to be less frequent than a home or commercial property which is used every day. Additionally, you could also choose a cesspool as a temporary solution on temporary locations like construction sites.

Septic tanks, meanwhile, are suitable to a bigger range of properties cut off from the main sewer system, including those used all-year round. As permanent residences have much more regular waste production, choosing a treatment system like a septic tank which partially treats the waste and disposes of it safely is a better choice and should prevent build up.

Cesspit or Septic Tank? The Pros and Cons

Now lets summarise the key points so you can easily see the advantages and disadvantages of septic tanks and cesspits.



  • Low installation costs
  • Good temporary solution
  • Stores huge amounts of waste


  • Requires regular emptying
  • High maintenance costs
  • Potential environmental contamination

Septic Tanks


  • Partially treats the waste inside
  • Produces wastewater to safely discharge into drainage system
  • Requires little servicing
  • Low maintenance costs
  • Better for the environment
  • Suitable for a wider range of properties


  • Higher installation costs

In Summary

Hopefully by reading this guide you will be in a better position to determine whether a cesspit or a septic tank is the best solution for your wastewater needs. In terms of the pros and cons, there are undoubtedly more advantages to choosing a septic tank over a cesspit, but there are still circumstances where a cesspit may be the solution for you.

For more detail and information on septic tanks, cesspits and the other wastewater services Owls Hall can offer you, feel free to get in touch for free advice and assistance.