Cesspit vs septic tank – which is better?

Are you weighing up the options of a cesspit vs a septic tank? This guide explains the pros, cons and costs.

Cesspits and septic tanks offer waste drainage solutions for many off-grid UK homes. They are part and parcel of rural life. But if you've never needed to install one before, choosing the right system for your home can be confusing.

What’s the difference between cesspits and septic tanks?

While cesspits and septic tanks do the same job, how they drain the waste is slightly different.

Cesspits store waste in a sealed tank underground. They require more frequent emptying because they don't have a drainage system.

In contrast, septic tanks have two chambers to separate solids and liquids. The solids settle at the bottom of one tank and break down over time. Meanwhile, the wastewater is filtered into a drainage field or soakaway system on your property's grounds. This means the tank doesn't need to be emptied as often.

Let's look at other pros and cons of each.

Cesspit vs septic tank: the pros and cons

Pros of cesspits:

1. Straightforward to install – As only one sealed tank is installed underground, it’s relatively simple and quick to install.

2. Low maintenance – Cesspits do not need to break down waste like septic tanks, which means there are fewer components inside the tank to monitor and maintain.

3. Less chance of contamination – Because cesspits are sealed, there is less risk of untreated wastewater seeping into the ground, unlike faulty septic tanks.

4. No drainage field needed – Cesspits do not need a drainage field, making them a better option for homes with poor ground drainage or limited space.

Cons of cesspits:

1. More frequent empties – Cesspits have limited storage capacity, so you’ll need a licensed waste disposal specialist to empty them more often. You'll need to do this on average once a month, but frequent monitoring to avoid an overflow is essential. There’s more on the emptying costs later.

2. Odour problems – If not maintained properly or left to overfill, cesspits can omit an unpleasant odour.

3. Regulations – Cesspits are subject to strict regulations set by the Environment Agency. To make sure your cesspit is in good condition and compliant with regulations, it’s good practice to have an inspection done at least once a year, along with the regular empties.

Pros of septic tanks:

1. Cost-effective – Once installed, septic tank maintenance costs are relatively low, as you won’t need to empty them as regularly as cesspits. As a general guide, your septic tank must be emptied every three to five years.

2. Eco-friendly – Septic tanks treat wastewater naturally, so they are considered a greener option than septic tanks that don’t treat waste.

3. Durability – Septic tanks can last for decades (up to 40 years or more!) if they are well maintained.

Cons of septic tanks:

1. Expensive to install – A septic tank has more upfront costs than a cesspit, especially for large or complex systems. However, it could save you money in the long run, as maintenance costs are low.

2. Planning permission and regulations – In addition to strict regulations set by the Environment Agency, you must also seek planning permission and approval from building regulations if installing a new septic tank. The same applies to cesspits.

3. Space and soil requirements – You’ll need sufficient space for the tank and a drainage field, which may not be possible for smaller properties. Also, not all soil types (such as clay soil) are suitable for a septic tank’s drainage field.

4. Costly repairs – Repairs can be expensive and disruptive if a septic tank system fails or becomes damaged.

Cost difference between a cesspit and a septic tank

Paying to install a cesspit or septic tank is one thing, but you also have to factor in the costs of regular empties.

This is one maintenance job you’ll want to keep on top of. After all, no one wants a blocked or overflowing sewage treatment system on their hands!

Let’s break the installation and emptying costs down:

Installation:

Most installation companies will quote a 'per project' rate for the installation and labour costs of your septic tank or cesspit.

However, to give you a general steer, labour costs to install a tank are between £1,000 - £1,400.

Remember that you’ll also need to pay for the tank itself. The cost of a septic tank ranges from £1,200 (small tank) to£1,800 (large tank).

Cesspit tanks are considerably cheaper, but remember, you must pay for monthly empties.

If in doubt, speak to your local septic tank and cesspit specialists for a breakdown of costs and options.

Emptying:

The cost of emptying a cesspit or septic tank depends on the size and the type of tank.

Emptying smaller septic tanks costsaround £175. Emptyingextra large septic tankscan cost around £225 - £400.

Meanwhile, quotes for emptying a smaller cesspit tank is £175. Emptying a large cesspit tank can be expected to come in around £225 - £400.

As you can see, there’s hardly any cost difference between the two. But remember, you'll be paying to empty a cesspit monthly compared to every couple of years for a septic tank.

For a more in-depth look at pricing, see our cesspit and septic tank emptying cost guide.

How to find a cesspit or septic tank specialist

At Checkatrade, we you can easily find highly-rated and qualified septic and cesspit tank experts near you.

Just enter your postcode in the box below and see which reputable septic and cesspit tank specialists are near you.

FAQs

Are septic tanks and cesspits the same?

Cesspits don’t have a drainage system, so they require more frequent emptying. Meanwhile, septic tanks separate wastewater and discharge it into the ground. For that reason, septic tanks don’t need to be emptied as frequently.

How do I know if I have a septic tank or a cesspit?

Locating the access hatch to your waste system and opening it safely and carefully will give you some clues. A septic tank typically has two chambers – one for solids and the other for liquids that flows out to the drainage area. Meanwhile, a cesspit is just one large sealed chamber.

Are cesspits still legal?

Absolutely. Cesspits are still legally used by many off-grid homeowners when septic tanks aren't an option due to the lack of land for drainage or poor soil quality. However, they are subject to strict regulations.

Does a cesspit need emptying?

Yes. Cesspits must be emptied frequently (monthly or more often) to comply with health and safety standards. Failure to do so could mean your cesspit overflows and contaminates the ground, which can result in hefty fines or legal action by the Environment Agency.

Can you sell a house with a cesspit?

Absolutely. Buyers looking to live in a more rural location will understand that a cesspit (or septic tank) is a house maintenance necessity. Just inform potential buyers about the cesspit and keep hold of any maintenance records, such as emptying schedules and service history. Buyers may request an inspection of the cesspit as part of their due diligence, which you might need to cover the cost of.

Cesspit vs septic tank: key takeaways

• Though a septic tank is more costly to install, you'll only need to pay to have it emptied every two to three years

• A cesspit is cheaper to buy and install, but you'll need to pay for monthly empties

• Be sure to follow all septic tank installation regulations and speak with your local authority to get planning permission