Log Out 
Everything you need to know about septic tank installation
Septic tanks provide practical and safe wastewater drainage in rural areas where there is no public sewer to connect to.
Whether you're installing a new septic tank system, or replacing an old one, there are strict laws and building regulations to comply with and processes to follow to ensure the new tank is installed safely.
Explore our septic treatment tanks
Contents:
- What are the rules for septic tank installation?
- Pros and cons for installing a septic tank
- How much does it cost to install a septic tank?
- Do you need to hire a professional to install a septic tank in the UK?
- A step-by-step guide to installing a septic tank
- Mistakes to avoid when installing a septic tank
- Septic treatment tanks from Forward Builders’ Supplies
What are the rules on septic tank installation?
The installation of all types of off-mains drainage systems, including septic tanks, is heavily regulated in the UK to protect the environment and public health from hazardous, untreated wastewater.
If you can connect your property to a public sewer, rather than using a septic tank, then you must do so.
The first, and most important, step when planning a septic tank installation is to familiarise yourself with the legal requirements by reading the 'General Binding Rules' on the Government’s website.
Septic tank discharging rules
One of the most important rules to note is that as of January 1 2020, septic tanks are no longer allowed to discharge directly into a watercourse like a river or lake.
Instead, wastewater must either:
- Pass through a sewage treatment plant before discharging into a watercourse
- Discharge into the mains sewer
- Discharge into a suitable drainage field
Other key regulations surrounding septic tank installation
- Septic tanks must be rated to BS EN 12566-1 standard
- Drainage fields must meet BS 6297 standard
- Septic tanks must be installed at least seven metres away from any habitable building
- Drainage fields should be positioned a safe distance from buildings, in accordance with Building Regulations and BS 6297 guidance
- Drainage fields must be at least 10 metres from watercourses and 50 metres from any well, spring, or borehole used for drinking water
- Discharges to the ground must be 2,000 litres or less per day
- The tank must be located within 30 metres of an access point for emptying
Septic tank permits and permissions
In some cases, you may need to apply for a septic tank permit from the Environment Agency, particularly if your system does not meet the General Binding Rules.
You’ll also need to get planning permission and building regulations approval, and perform a site survey before beginning your project, to make sure that your site is suitable for a septic tank.
What are the pros and cons of installing a septic tank?
Before deciding whether a septic tank is the right option for your property, it's important to understand the pros and cons of installing one.
| Pros | Cons |
| Long-term cost savings A well-maintained septic tank can last for decades, saving money on monthly water bills | High upfront cost Initial purchase and installation costs can run into the thousands of pounds |
| Environment-friendly Septic tank systems use very little energy, making them an environmentally responsible solution for managing wastewater | Requires land You need a significant amount of land to install a septic tank |
| Self-sufficient Septic tanks operate independently, so you're not reliant on the local sewage system | Potential for issues While septic tanks are low maintenance, it's important to have them regularly serviced to avoid problems like backups and overflows |
How much does it cost to install a new septic tank?
The upfront cost of buying and installing a new septic tank is high, but a well-maintained system can last for decades, and gives you independence from the public sewage system.
Many people find septic tanks to be a cost-effective solution, helping them to reduce their ongoing sewerage charges in the long term.
Typically, the annual cost of maintaining and servicing a septic tank is less than you would pay a water company to use the mains sewerage.
Septic tank prices
Septic tanks vary in price depending on factors like capacity, material, and outlet type.
At Forward Builders' Supplies, our septic tanks range in price from £987 for a basic 4-person treatment tank to £2,625 for a 6-person ENCO gravity tank.
Professional septic tank installation costs
However, buying the tank is just one small part of the installation cost.
Here's a rundown of the average prices you can expect to pay a professional installer:
- Replacing an existing septic tank: £4,000-£6,000
- Replacing a septic tank and creating a new drainage field: £9,000-£13,000
- Installing a new septic tank system: £8,000-£15,000
Bear in mind that these prices will vary depending on a variety of factors, including the size of the tank you need and the location you live in.
Do you need to hire a professional to install a septic tank in the UK?
In theory, with the right machinery, tools, equipment, and know-how, it is possible to install a septic tank yourself – but it's not advisable.
Most people hire a team of professionals to carry out the job, especially when installing a new system rather than replacing an old tank.
As well as being a labour-intensive job, there are lots of rules and regulations (outlined above under ‘What are the rules for septic tank installation?’) that you need to follow.
Incorrect installation can have serious safety, legal, and financial implications, and hiring a professional installer will give you peace of mind that your tank has been installed safely and in compliance with all relevant laws and building codes.
How to install a septic tank (step-by-step guide)
So, how to fit a septic tank?
The process varies depending on factors like the size and type of tank being installed, ground conditions, and local building regulations.
The job requires specialist knowledge to ensure that the system works efficiently, and the tank is installed safely and in compliance with all relevant regulations.
Our easy-to-follow guide below lists the key steps usually required to install a septic tank, but should be adapted according to your unique site conditions and system specifications.
Step 1: Site survey and planning
Carrying out a full and detailed site survey will help you to identify the most suitable tank, drainage field, and position to install your system in.
If you're creating a new drainage field, you should also carry out percolation tests to assess how well the ground can absorb wastewater.
Step 2: Prepare the site
With your plans in hand, it's time to clear and prepare the area.
During this stage, you'll need to clear any plants, vegetation, fences, and other obstacles, ready for installation and to ensure easy access to the site.
Step 3: Excavate
Now you need to dig the hole that your septic tank will sit in – a mini excavator will help you get the job done quickly.
Refer to the tank's manufacturer's instructions for detailed information about how deep the hole should be.
Remember, it needs to be deep and wide enough for the bedding material, tank, and backfill material.
Step 4: Install the base layer
Next, you'll need to lay a stable base to prevent the tank from moving over time.
The manufacturer's instructions should recommend the most suitable bedding material and depth; usually, concrete or granular bedding is best suited for the job.
Step 5: Position the tank
Before lowering your septic tank into the hole, make sure you check it over carefully for signs of damage.
It'll be much easier to replace a faulty tank now than after installation!
Make sure you know which way round the tank needs to go for connecting the inlet and outlet pipes.
Then carefully lower it into the hole according to the manufacturer's safety recommendations.
Step 6: Connect the inlet and outlet pipes
With your septic tank in position, it's time to connect everything together.
The inlet pipe connects your tank to the property, and the outlet pipe carries the treated wastewater to your drainage field.
Pipework must be installed to the proper fall and securely sealed to prevent blockages, leaks, or poor flow.
Step 7: Cover the septic tank
Finally, once you're happy that everything is as it should be, it's time to cover the septic tank using a suitable backfill material, as recommended in the manufacturer's instructions.
Take care to ensure that all access covers are left uncovered for future inspections and maintenance.
Mistakes to avoid when installing a septic tank
Installing a septic tank is a major project and a significant investment, so it's important to get the installation right the first time.
Mistakes during the planning and installation process can result in drainage issues, expensive repairs, and even compliance issues further down the line.
To help you avoid common pitfalls, we've put together this quick guide to some of the most frequent septic tank installation mistakes and how to avoid them.
Installing the wrong size septic tank
Installing a septic tank that is too small for the volume of waste your property produces can cause maintenance issues and shorten the system's lifespan. Equally, if you buy a tank that's too big, you'll pay more than necessary for a system that won't be fully utilised. A specialist installer can help you calculate the most appropriate tank capacity for your needs.
Failing to carry out a proper site survey
A detailed site survey should assess the suitability of factors like ground conditions, soil drainage, groundwater levels, and available space. If the conditions aren't quite right for a septic tank, then this should be picked up during the site survey. Cutting corners during this stage could result in a septic tank system that doesn't drain properly, floods, smells bad, or even fails completely.
Failing to apply for a permit or planning permission
Not finding out exactly what permissions are required before installing a septic tank can be a very costly mistake. Overlooking the importance of this step could result in heavy fines, enforcement action, costly remedial work, or even complete removal of your septic tank system.
Choosing the wrong location
Installing your septic tank in the wrong position can create serious long-term problems, including contamination risks and expensive remedial work. When choosing a suitable position, you must comply with regulations regarding minimum distances from buildings, boundaries, trees, and watercourses, while also ensuring there is safe and practical access for future maintenance and emptying.
Inadequate bedding material
Your septic tank needs a stable and level base to prevent it from moving over time. Using unsuitable bedding material or failing to compact it can compromise the tank's structural integrity, causing damage over time. Always refer to the manufacturer's installation instructions for advice on the best type and depth of bedding material for your septic tank.
Septic treatment tanks from Forward Builders' Supplies
Does your next big project involve installing or replacing a septic tank? If so, we can help!
At Forward Builders' Supplies, we stock a wide range of septic tanks, from small 4-person tanks to large 10-person tanks.
If you need help selecting the right septic tank for your property, contact us on 0151 357 1035, and we'll be happy to help.
All our products are manufactured by leading septic tank brands like Marsh Industries to ensure effective, long-lasting performance.
We also offer free delivery to customers located within 50 miles of our depot in Ellesmere Port, Cheshire.
The information below is required for social login
Login
Register
Fill in the form below to create your new account