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5 Factors Affecting Septic Tank Costs

Though many people living in the city take sewer systems for granted, if you live in a rural location you’ll know only too well the importance of septic tanks. Where there’s no mains sewage to connect to, homes need a septic tank fitted, providing a place for baths, toilets and dishwashers to drain into – they need emptying at least once a year depending on their size and are an essential component of any drainage setup.

In this article, we’ll be exploring:

  • How much septic tanks cost
  • What affects the cost of a septic tank
  • How to save money on septic tanks
  • How to know if a septic tank is the right choice for your home
  • How to find and hire a company to take care of your septic tank for you

If you live in a rural location, or are moving to one soon and want to get clued up on the ins and outs of septic tanks, keep reading to find out everything you need to know – from installation to maintenance.

How Much Do Septic Tanks Cost?

The price you can expect to pay for a septic tank will change depending on the size you opt for, and whether you want an above or below ground tank. Let’s take a look at some of the most common types:

Above Ground (up to 2,200L) £1,100 to £1,650 £300 to £800 2 to 4 days £1,600 to £2,450
Above Ground (up to 3,400L) £2,100 to £2,300 £450 to £1,000 3 to 5 days £2,550 to £3,300
Above Ground (up to 4,500L) £2,400 to £2,750 £750 to £1,400 5 to 7 days £3,150 to £4,150
Below Ground (up to 2,800L) £720 to £1,300 £1,200 to £1,800 2 to 4 days £2,000 to £3,100
Below Ground (up to 3,800L) £1,000 to £1,500 £2,000 to £2,500 3 to 5 days £3,000 to £4,000
Below Ground (up to 4,800L) £1,200 to £1,860 £2,700 to £3,350 5 to 7 days £3,900 to £5,210

Above ground septic tanks are great for homeowners with land that is typically unsuitable for below ground installations due to a risk of the equipment failing and not working as intended. It’s important to get the right size tank for your household, as too small will lead to overflowing waste, and too big will cause issues with breaking down the materials inside the tank.

An above-ground septic tank with a capacity of up to 2,200 litres comes with an estimated supply cost of between £1,100 to £1,650. You’ll want to set aside two to four days for installation, as well as between £300 to £800 to cover the installation costs.

The total estimated cost for an above-ground 2,200-litre tank is within the range of £1,600 to £2,450.

Moving up the sizes, an above-ground up to 3,400-litre tank will cost between £2,100 to £2,300 for supply costs only, with an additional £450 to £1,000 installation cost, taking between three and five days to fit.

The total estimated cost for an above-ground 3,400-litre tank is between £2,550 to £3,300.

The last in our range of above-ground septic tanks is a 4,500-litre capacity, which holds a supply cost of between £2,400 to £2,750. This will take between five to seven days to instal, costing an additional £750 to £1,400.

The total estimated cost for an above-ground 4,500-litre tank is between £3,150 to £4,150.

Below ground septic tanks are great options for those wanting a hidden and discreet sewage system with adequate space to do so.

A below ground septic tank with 2,800-litre size carries a supply cost of between £720 to £1,300. It’ll take between two to four days to fit, and this will carry a charge of £1,200 to £1,800.

The total estimated cost for a below-ground 2,800-litre tank is between £2,000 to £3,100.

Next up is the below-ground 3,800-litre septic tank, costing between £880 to £1,500 for supply only. Taking between three to five days to install, it’ll cost you £2,000 to £2,500 to have fitted.

The total estimated cost for a below-ground 3,800-litre tank is between £3,000 to £4,000.

Finally, we’ll look at a below-ground 4,800-litre septic tank, costing between £1,200 to £1,860 for supply. This carries the longest installation period of our selection at between five to seven days, and will cost you an additional £2,700 to £3,350 to fit.

The total estimated cost for a below-ground 4,800-litre tank is between £3,900 to £5,210.

Are you ready to start your septic tank installation? HouseholdQuotes can help you find the right septic tank installer.

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What Affects the Cost of a Septic Tank?

Septic tanks can quickly spiral into very expensive pieces of equipment. Here’s what you need to look out for when planning your installation.


As you might expect, the size of your tank will have a direct impact on the cost.

In the UK, building regulations stipulate you must buy a tank that is at least 2,700 litres, or 2.7 cubic metres, which will be sufficient for four people. If your household has more people living in it, then the rule of thumb is to add 180 litres for every additional person.

While you might not have permanent residents at your home, if you regularly entertain and have friends and family lodging at your house, you’ll need to consider if your septic tank is up to the challenge. For reference, a 3,750-litre tank can serve up to 11 people, and a 4,800-litre tank can serve up to 18 people – so no matter how big your parties are, there’ll be a tank suitable!

It’s essential to remember that septic tanks don’t only take used toilet and bathroom water, but wastewater from washing machines and dishwashers too. All wastewater from your home will be draining into one of these tanks, so you must have a tank fitted with adequate space.

Too small, and you’ll discover you need to have the tank emptied more frequently, pushing maintenance costs up – yet, a large unit not only costs more, but it can also limit the number of tanks to choose from, as larger tanks normally need to be installed below ground.

Location (Above or Below Ground)

The location of your septic tank will have an impact on the installation costs; whether it’s above-ground or below-ground, and both tanks come in different styles.

Above-ground tanks are normally cheaper and are great if you only need a small system. The most affordable choices are shaped like low-profile boxes, which can be connected if you need more wastewater storage.

Above-ground tanks are cheaper to instal, but they require regular emptying, which can become expensive over a tank’s lifetime.

Alternatively, you could research having an underground tank fitted – these aren’t cheap, largely due to the installation costs, which include having to dig a hole large enough to contain the tank in and prepare the right footings. However, on small sites, you may have no other option than to buy a below-ground tank as space on the surface may be at a premium.

Below-ground tanks can be onion-shaped or low-profile cylinders (also called shallow dig septic tanks), with the onion-shaped tanks being the most common style in the UK.

Before deciding what’s right for you, you should always check local regulations before buying your tank as some councils restrict the variety of septic systems you can use.


Draining systems are required for below ground tanks, and setting this up may also add to initial costs.

The benefit of a large, underground tank is that a soakaway can be fitted, allowing some of the wastewater to be filtered out into the surrounding ground. As a result your tank is able to be emptied less often, saving you money in the process.

Of course, before you have a tank fitted, you will need to ensure the ground is suitable for a soakaway and will be able to absorb some of the excess water. Getting this checked over and having any required pipe and drainage works installed will push up the project’s price, but it is an essential and unavoidable step.


The cost of septic tanks is also affected by the material they’re made of. Unsurprisingly, the better quality materials are more expensive, but if you can afford the initial outlay, it’s worth paying a premium because the tank will last longer.

The typical materials you’ll encounter will be:

  • Concrete
  • Plastic
  • Fibreglass (also called GRP or Glass Reinforced Plastic)
  • Steel

Some of the cheapest tanks are made of concrete. Whilst this allows you to buy an inexpensive septic system, they don’t last long and you’ll have to replace them regularly.

Alternatively, a high-density polyethylene model, though costing a lot more initially, will last far longer and is more financially economic.


Labour will have a huge impact on septic tank installation costs – this can range from the hundreds up into the mid-thousands for below-ground tanks. And, if you’re having a tank replaced, you’ll need to factor in the cost of having the old septic system removed, too.

Annual Maintenance Costs

You are legally required to hire a licensed waste carrier to remove septic tank wastewater, which will add extra fees to your annual running costs. This can cost between £100 to £200 per year depending on the size of your tank and your location.

How Can I Save Money on a Septic Tank?

Comparing quotes is a great way to potentially reduce the cost of septic tank installation. HouseholdQuotes can help you get quotes from multiple septic tank installers near you, so that you can find someone that suits your budget.

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Now we know how septic tanks can be expensive, let’s go through some of the cost-saving tactics to keep some extra fees at bay.

Luckily, the pre-installation is an area you can save some money on.

If you’re having a below-ground septic tank installed, you might want to consider preparing the ground for your installers yourself. It’s relatively simple to dig a hole, and the cost of hiring a digger will be far less than having a professional team install the tank.

What’s more, if you have some basic plumbing knowledge, you could even install the entire drainage system yourself – but if you’re unsure about anything, it’s always more cost-effective in the long run to get things done professionally in the first place, instead of requiring emergency assistance further down the line.

While you can save money by preparing the site yourself, it’s worthwhile buying the best tank possible for future savings. If you expect your family to grow, then buying a tank that’s just right for now might seem like the cheapest option, but if in a few years you need to have something a lot bigger, the cost of removal, digging and re-fitting will outweigh the initial cost.

This point extends to the material you opt for. While concrete may be a cheap option, it isn’t the best in terms of longevity, and you’ll end up replacing it far sooner than you’d wish.

It’s worth waiting to save a little bit extra to get something that will suit you for years to come, both in size and in the material.

Is a Septic Tank the Right Choice for My Home?

Let’s take a look at the key advantages and disadvantages of having a septic tank installed.

Sewage option for those living off-grid Planning permission may be necessary, making it hard for some homeowners to get in place
Environmentally-friendly Adequate land is needed to place the septic tank
Durable when made with long-lasting materials Installation costs can be high – especially for below ground systems
If well maintained septic tanks can last years Periodical maintenance is needed

The main advantage is that a septic tank gives a vital sewage option for those living off the grid in rural locations, while also being environmentally friendly as the treatment relies on naturally occurring reactions. Septic tanks are durable when created in long-lasting materials, requiring little attention over the years if well-maintained.

The disadvantages concern planning permission, which can be troublesome to acquire in listed properties, and you must make sure that your installation complies with building regulations before getting started. Septic tanks require land and space to be stored, either above or below ground, and installation costs are high – especially for below ground systems.

Periodical maintenance is needed, which will be a cost to you as the homeowner.

Are There Any Alternatives to a Septic Tank?

If you don’t like the sound of a septic tank, or simply haven’t the space for one or permits for one at your property, there are alternatives to traditional sewerages.

  • Mound System – carrying high installation costs and the need for a lot of land
  • Plastic Chamber Leach Field – again, the need for land is essential to this method
  • Constructed Wetlands – needs considerable maintenance and care to look after the wetlands

What’s Involved in Installing a Septic Tank?

Whether you’re replacing or installing a brand new septic tank into your land, these are the following steps your installer is likely to take.

Before getting started, it’s essential that you ensure the correct planning permission is in place to avoid any issues after the installation. It’s a good idea to inspect the tanks when they arrive as if there are any damages to it, this will impact the performance.

A hole will then be dug deep enough to house the tank and other equipment – or, if you have a septic tank and are simply replacing it, the old tank will be lifted out and disconnected ready for the new one to be installed. The base will then be installed ready for the tank.

The septic tank will then be lowered into the hole, and the space will be backfilled with either concrete, gravel or sand, depending on the manufacturer’s guidelines. The pipes for your drainage field will then be laid, and the pipes can then be connected once everything is in place.

Finally, your manhole cover will be fitted.

How Do I Find and Hire a Company to Install or Maintain My Septic Tank?

Finding the right septic tank installer can be challenging. At HouseholdQuotes, we can connect you to septic tank installers in your area.

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A good first port of call is to seek out recommendations from family, friends, and neighbours who live in a similar geographic area to you or know people who might need the service of a septic tank.

This way, you can carefully navigate away from potential rogue traders and instead enlist the help of someone pre-vetted and ready to go.

Ensuring the Professional Is the Right Fit

Having a written quote in your hand is an essential first step in any home renovation job – and with your septic tank, this is no different. You want to be sure that the number you’re quoted in the beginning will remain true come the end of your project.

This should include the answers to questions such as call out charges, minimum fees, and if there are any additional labour fees to pay for certain types of septic tank installation.

You should find out the trader’s experience on similar jobs, by looking at their references and any associated photographs or videos of their work to make sure it’s a match for what you’re looking for.

Finally, your traders should carry insurance, but it’s always best to double-check this before any work gets started on site.

Final Checklist

If you’re considering having a septic tank installed, or desperately need to upgrade your existing one and want to get started as soon as possible, take note of our final checklist to ensure everything is taken care of.

  • Is a septic tank right for you? Make sure you’ve scoped out if it’s the best option for your property
  • Under or below ground? Check with your local council to see if there are any stipulations to what you can and can’t have
  • Get the right size tank for you – considering if you host for guests regularly, which will boost your internal capacity

Use HouseholdQuotes to find local septic tank installers and potentially save money on your septic tank installation.


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Frequently Asked Questions

What Does a Septic Tank Do?

Septic tanks are a way of treating domestic sewage in areas where there isn’t a centralised sewage point. Inside the tank, bacteria breaks down harmful substances.

Do I Need Planning Permission for a Septic Tank?

If you’re installing a new septic tank, you’ll need both planning permission and building regulations approval.

If you’re replacing an existing tank, you will still need building regs approval. In either case, it’s a good idea to contact your local planning authority, and you can find the contact information for your local council here.

What Are the Rules for Septic Tanks From 2020? Do I Have To Upgrade My System?

In 2015, the government introduced new legislation, giving septic tank owners until 2020 to comply and adapt their systems to fit the new rules.

If you already own a septic tank, you may need to upgrade your system to make sure it complies with the law. You can find a short summary of the rules for England here. The rules are different in WalesScotland, and Northern Ireland.

How Often Should You Empty a Septic Tank?

The answer to how often you should empty your septic tank lies with how many people are in your household, but a good rule of thumb is between three to five years.

What Are the Signs That My Septic Tank Is Full?

There are a few tell-tale signs that your tank is full, from unusual or new odours, slow drainage, and issues with flushing toilets. There’s a thorough breakdown of all the signs on this page.

Do Septic Tanks Smell?

Septic tanks shouldn’t smell terrible – if they do, it’s usually a sign there’s an issue with installation or that your tank needs to be emptied.

How Much Does It Cost To Build a Soakaway?

It should cost around £300 if you build a soakaway yourself, or between £750 to £1,500 if you hire a professional. For more information on soakaways, take a look at our dedicated page.

Ready to start your project? We can help!

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