Most of us, when we think of a drain, imagine pipes underneath the ground, leading to a sewer and away. Yet there are different types of drainage systems such as septic tanks and cesspools. Never heard of them? Don’t worry we will explain everything…


What is a septic tank?

This method of drainage uses an underground tank to treat household wastewater produced by kitchens, bathrooms, and showers. This is done through a process of biological decomposition and drainage.

Rural houses may rely on this water disposal system as connection to a sewer might not be possible.


How do septic tanks work?

Wastewater flows from the house to the tank. This wastewater is then separated into three layers, water, sludge, or scum. Any sludge or scum remains in the tank which must be emptied periodically. The water is released through a filter called a baffle to a drainage field.

The drainage field allows the wastewater to enter the soil, spreading it evenly, where it is purified therefore removing harmful bacteria and viruses.


What is a cesspool?

This is a tank located under the ground purely to store all waste a household produces. Much like a septic tank this is vital for those who live too far from a sewer, or it is too expensive to connect the drainage system to a sewer.


How does a cesspool work?

Wastewater leaves the house through the drains and enters a tank where it is stored until to is time to be emptied. Unlike a septic tank there is no water purification.


Problems that may occur…

Failure to regularly empty the tank will result in a build up of sludge. This happening within a septic tank could potentially cause waste to enter the drainage field, limiting the filtration of water.

For both types of drainage systems, a leaking tank could result in waste entering groundwater causing an environmental hazard.

Tree roots and ground movement can also affect the tank causing fractures and leakages.

If there are damp spots or bight green grass around the tank this could indicate an issue. Along with the usual telltale signs of a drainage problem, such as bad odors and water backing up.


Things to consider about septic tanks and cesspools…

Firstly, the size of the tank. It goes without saying that the bigger the tank the more it will cost but having a tank too small will result in it being emptied more often therefore costing more on maintenance. Remember this drainage system has to cater for all your wastewater, not just bathroom waste.

Secondly, what the tank is made of. The material will have an impact on the price, but better material means a longer lasting tank. An inexpensive tank means it will have to be replaced forcing you to pay for removal of the tank on top of the cost of the new one.

Thirdly, the location is key. It is possible to have an above ground tank and they tend to be cheaper, however these tend to be smaller systems resulting in more regular emptying. Although on smaller plots an underground tank may be the best option but will require a quick check of local council regulations.

Finally, and specifically for septic tanks, the ground must be suitable for filtering the water. Getting this checked will result in greater cost.


Much like regular drainage systems these systems need to be regularly checked and maintained. The only difference is failure to do so will result in far greater costs and a far more complex task for those repairing or replacing the system.

If you have a problem with your drains, whatever your drainage system, please get in touch today by clicking here.