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A Homeowners guide to owning or buying a house with a Cesspit or Cesspool. Including regulation, maintenance and emptying costs.

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How does a cesspit work?

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A cesspit is just a big watertight container in the ground. It collects all of your effluent and wastewater and holds it. Once the cesspit is full it will need to be emptied. The effluent is not treated or discharged. To note a Cesspit and Cesspool are essentially the same things. The key is that this type of system does not have a discharge or any type. Cesspits are rarely installed anymore unless there is no other option. This is because water usage has increased markedly since this type of system was commonly installed. This increase in water use and hence discharge has made this type of system uneconomical to maintain. Further, as you will see later in this article the required size of a modern cesspit is vast. Yet the lorries that empty them are only so big and are designed to empty septic tanks of 1,000 to 2,000-gallon capacity.

What we generally see is that the old cesspit systems have been adapted to leak or have had a form of outlet added. As a Cesspit offers no treatment to the wastewater this leads to pollution and illegal activity.

What is the difference between a septic tank and a cesspit?

Septic tanks generally have two chambers, Cesspits a single chamber. A Septic Tank uses the two chambers to separate out the solids and top-level scum. The remaining element is discharged either to a drainage field or ditch/watercourse. From the 1st of January 2020, it will only be legal to discharge a septic tank to a drainage field. The key difference is a Septic Tank has a discharge and even if it just has a single chamber it was specifically designed to discharge and offer a form of treatment. This type of rudimentary treatment is undertaken by simple T-Pieces which stop the bulk of the sold waste from escaping into the outflow.

What is the difference between a sewage treatment plant and a cesspit?

A sewage treatment plant actually treats the effluent that goes into it discharging near clear water. A cesspit does not treat the effluent in any way and does not discharge any effluent. A Sewage Treatment plant that meets the appropriate British Standards set can discharge into Surface water. 

How often does a cesspit need emptying?

A Cesspit needs to be emptied before it gets full. A Cesspit has no discharge so the frequency of empty is dependent on how much effluent is put into it. The average discharge per person is 150 litres per day. Cesspits come in various sizes, let’s assume a 24,000L capacity. 4 people will fill this in 40 days. So the tank will need emptying every 40 days.

How much does it cost to empty a Cesspit?

In the example we used above, a 24,000L cesspit will cost approximately £600 to have emptied and is VAT exempt for domestic users. So if you need to have the tank emptied every 40 days then you are looking at an annual cost of £5,400.

What regulations are there for Cesspits?

Cesspits are illegal in Scotland. In England, you can have a Cesspit but it is your responsibility to ensure that does not leak or overflow. Many Cesspits are very old and porous; many I have seen have been intentionally damaged so they discharge to reduce cost. The Environment Agency will fine and prosecute for any illegal discharge made.

When would you install a new Cesspit?

Cesspits should be used as a last resort or for temporary drainage situations. In terms of last resort, this is where you have no chance of a discharge of any type, this is normally because of the geology in the area prevents drainage. Cesspits are normally huge, you will also need a lot of space!

Another use is for example on campsites to capture chemical toilet or hot tub waste which would otherwise stop aerobic digestion in a septic tank or sewage treatment plant.

Should I buy a house with a Cesspit?

As a permanent drainage solution, a Cesspit should be avoided. I would not buy a house with this type of system due to the annual cost of emptying. If you are looking to buy a house with a Cesspit you need to find out why it has a cesspit and can a sewage treatment plant be installed. Generally, if there is a Cesspit it is normally because there is a reason that a septic tank or sewage treatment plant could not be installed. As detailed in the regulation section many cesspits are damaged and leak, this is an illegal discharge. Personally, I would also be very wary of groundwater and soil type in these situations. Do your homework!

What size cesspit do I need?

The size of cesspit or cesspool needs to be based on the number of people in the property, generally based on bedroom numbers. A one-bed property is classed as having two people, the minimum size 18,000L. For each extra bedroom/person add an additional 6,800L capacity.

If a Cesspit is not the right solution

If after reading this a Cesspit is not the right solution for you then we would strongly recommend that you look at a Sewage Treatment Plant. Please have a look at our buying guide and installation page. The main reason not to have a Cesspit is to allow an element of your household discharge to flow away. This means you are only paying for an annual empty not the emptying of all of the discharge from your property for the whole year. You should only really be considering the installation of a Cesspit if there is nowhere for you to discharge to.  

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A guide to Cesspits and their ownership
Cesspits do not have an outlet and are normally centuries-old designed for a time when water usage was far less. The cost of emptying them can with modern water usage be eye watering.
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Homeseptic Ltd
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