Living with Nature: Understanding the Importance of Cesspools in Off-Mains Drainage Systems

For those that have escaped the big city and are living with nature, you likely know all too well how important cesspools (or cesspits) are. Without access to the public sewer system, cesspits and other off-mains drainage systems, collect the liquid waste generated from households and businesses.

If you’re not in the know, cesspools are essentially a sealed underground container that stores any sewage or liquid waste. Unlike a septic tank or public works, there isn’t any treatment, filtration or disposal happening – simply storage.

This means that cesspools will need to be emptied more often, which can affect the price of maintaining one. Which may lead you to wonder – why use a cesspool over a septic tank?

Cesspools are typically favoured in locations where you cannot get permits to discharge waste into soakaways, as a septic tank would do. Instead, the waste would be temporarily stored and frequently removed.

So, how much will different cesspools set you back?

Concrete Cesspool

Being one of the most commonly used materials for cesspools, concrete is a fairly economical choice for a cesspool. If installed and maintained correctly, a concrete pool will also have a long lifespan. The enormous weight of a concrete cesspool will also prevent it from floating when near capacity.

Unfortunately, the sheer weight of the material will increase the costs of purchase and installation. It would require large equipment to transport and install it, especially if you’re using a pre-casted concrete cesspool, which will complicate the installation. This can also make concrete cesspools unfeasible for certain hard to access properties, so keep that in mind!

Another aspect to keep in mind is quality. When using concrete you shouldn’t cut corners on price, as poor installation or poor-quality material can result in leaks and cracks. Granted, this is prevalent with the other materials but the risk is much higher when using concrete.

Brick Septic Tank

Though all cesspools at one time were made using brick, it’s seen less use recently due to the rise of plastic and fiberglass. In many ways, they share many of the disadvantages that concrete cesspools have. They’re prone to leaks and the material is quite cumbersome to transport and install. In general we would recommend any of the other materials for a new installation.

Plastic Septic Tank

To specify, plastic cesspools will typically be made of polyethylene or polypropylene. These offer a number of advantages over brick and concrete tanks. Unlike those materials, plastic is resistant to erosion or cracking, which means there’s a much-reduced chance of any leaks or breaks. Furthermore, their lighter weight allows for much easier, and therefore cheaper, installation and transportation. Polyethylene is, in general, one of the cheapest long-term options for a cesspool.

Unfortunately, their lighter weight can also be their downfall. As the tanks will weigh less than the water inside of them, they are liable to float in areas where the water table is high. As such, they will likely need to be anchored if they are being installed underground. Finally, polyethylene and polypropylene aren’t nearly as strong as the other materials mentioned here, so will be damaged in extreme conditions. If that seems likely, then you may want to look into the following…

Glass Reinforced Plastic Septic Tank

GRP (Glass Reinforced Plastic) are as you would expect, similar to plastic cesspools but have been reinforced with glass fibres. This will naturally increase the costs in relation to polyethylene, but the combination of high durability and lightweight can certainly be worth it. Many companies, especially these days, will only sell fibreglass plastic cesspools, so it’s certainly worth a look.

What’s the average cost to install a cesspool?

As with pricing the actual pool, there are a number of factors that can affect the cost to install a cesspool. This includes the size of the tank, the location of the site, if it’s above or below ground and the materials you’re working with.

Not including the purchase of the cesspool itself, installing a cesspool will often be considerably more expensive than installing a septic tank. While a septic tank is more complicated, as they frequently have two or more chambers and a required soakaway on top of that, the sheer size of cesspools makes them quite expensive to install.

You should allow for around £3000 – 6000 for the entire project.

How much will emptying a cesspool cost, and how often should you do it?

Unlike a septic tank, cesspools require emptying very frequently. The exact number will come down to the capacity of your pit, and the average amount of waste your household or business produces. On average, you should expect to empty yours around every 45 days, though potentially more if it is used by a family of 4 or more.

As such, the cost of maintaining a cesspit can be very costly. A single occupancy house would likely need a 24,000-litre cesspool. The cost of emptying one of that size could cost you around £500 – 700. Looking annually, that comes to between £4000 – 6000. Naturally, these prices would be much higher for larger tank sizes, especially as cesspools can reach up to 220,000-litres capacity in extremes. If you’re trying to work out a good-sized cesspool for a family, take the minimum size of 18000-litres and add around 7000-litres per person.

Due to the sheer expense, a cesspool should only be used if there is not other option (such as a septic tank or sewage treatment plant) or if it would see infrequent use.

Finally, it should be noted that cesspools are currently illegal in Scotland. They are legal in England and Wales, but the responsibility is on you to ensure there are not any leaks or overflow. Similarly, cesspits can only be emptied by a licensed waste disposal contractor – do not try it yourself. It is both illegal and highly dangerous.

Callum Vallance-Poole


Marketing Coordinator - Based at our UK HQ in Banbury, Oxfordshire, Callum is responsible for promoting Water Management Systems, Attenuation Tanks, Treatment Plants, Rainwater Harvesting Systems and more!