If you’ve never heard of a septic tank, you probably live in a town or city where your solid and liquid waste discharges down the drain. If you live in the country, you may not have this luxury. So, the only way to safely discharge waste from toilets, baths, showers, sinks, washing machines, etc. is to drain into a septic tank and let nature take its course.
How Much Is A Septic Tank? (including labour cost)
As you might expect, new or replacement septic tank installation costs can be high depending on where you live, the type of ground you have nearby and many other factors.
The average cost to buy a septic tank ranges from £800 for a small one to £1500 for a large one. The cost to install ranges from about £2000 to £4000.
On average, the total quote you may receive may be anywhere from £2500 to £3500 in total.
Factors To Consider For The Job
Septic Tank Installation
- Replacement or new septic tank. You’ll find a difference in septic tank replacement costs compared to a new installation as much of the infrastructure will already be there.
- Pipework. Replacement tanks will already have the connecting pipework from the house, whereas new ones will need the added expense of purchase and installation.
- Foundations. New installations will need concrete foundations for the tank, while replacement tanks won’t.
- Disposing of soil. When you dig out the holes needed for tank and soakaway, you’ll produce a lot of soil. Yes, some of this will be used up with back-fill, but there will be a lot of leftovers, and you’ll have to put it somewhere.
- Empty tank. If you’re replacing an old tank, you’ll need to empty all the sludge that’s built up over time before you can move it. You’ll also have to rinse it out until it’s safe enough to remove it to the waste disposal site.
- What type of subsoil. The underlying geology of your subsoil will govern how easily the tank can drain. Clay will be extremely difficult and you might have to install additional drainage.
- Type of contractor. A specialist contractor may take on the entire job and supply the tank too. A local building contractor may call in specialist subcontractors.
- Project duration. This depends on the type of ground and whether the tank needs new foundations and plumbing. Durations range from 3 days to 7 days.
Factors involved with the purchase costs include:
- Size of tank. Both the size and construction material will vary the purchase cost.
- Type of retailer. You’ll have a choice of specialist supplier or building supplies merchant, both of which will have their own range of prices.
Remember when asking for quotations that most contractors won’t add VAT to their final figures unless you ask.
Another thing to remember is that prices will vary depending on where you live. London and the South East of England will be more expensive than anywhere else.
How Do Septic Tanks Work?
There are two distinct ways to use a septic tank. With a soakaway and without.
As from 1st January 2020, it is now illegal to use a septic tank that discharges directly into a surface waterway, without using a soakaway. We, therefore, won’t consider this type. We’ll talk in more detail about this in the next section when we deal with the regulations.
Septic tank with a soakaway
Older tanks were made from brick or concrete. Most modern ones can be made from fibreglass or polyethene.
A septic tank settles and retains the fine solids inside the tank until levels rise enough for the tank to be emptied. Depending on the amount discharged from the house, this can take months or years.
Bacteria digest the dirty water while in the tank, and as it seeps out into the soakaway or drainage field natural bacteria found in the ground continue the treatment. For this to work correctly, the septic tank must have a thriving bacteria population and the surrounding subsoil must be free draining.
Over time, the bacteria in the subsoil creates biomass which can interfere with the drainage. At this time, the effluent will leach to the surface or back up along the pipework to the house.
The household needs to use biodegradable cleaning materials. Regular cleaning materials such as bleach, detergents and other similar products interfere with bacterial growth and the settlement of solids within the tank and in the drainage field.
UK Regulations & Planning Permissions
On 1st January 2020 new rules came come into force regarding septic tanks discharging to surface water. Now, installations cannot discharge directly into a surface watercourse. All septic tank discharges have to drain into a drainage field (also called an infiltration system) or must connect to some other small sewage treatment plant.
To install a new septic tank you must have planning permission and comply with the UK Building Regulations as well as hold a permit. If you are replacing an existing tank, you usually don’t need planning permission. If in doubt, contact your local authority for advice.
When dealing with sewage and wastewater disposal, it’s important to use suitably qualified contractors to ensure they follow the various regulations. One of the trade associations, British Water has a list of accredited wastewater treatment plant technicians who will install and maintain your septic tank or other types of the sewage treatment plant in line with current regulations.
Septic Tank F.A.Qs
Can you have a septic tank without a leach field?
From 1st January 2020, all septic tanks must drain through a leach field and not directly into a surface watercourse. There are two alternatives to this arrangement.
- Connect to a mains drainage system.
- Connect to another type of sewage treatment plant.
Does shower water go into a septic tank?
All wastewater from inside the house must be diverted to a septic tank. This includes water from toilets, sinks, showers, baths, washing machines etc. However, rainwater runoff from roof guttering does not have to be treated. In fact, it’s better if it isn’t, otherwise, the bacterial balance will be affected and the tank will be filled to overflowing faster than the water can soak away.
How long does a septic tank last?
This answer depends on the material from which the septic tank is made. A steel one will last for up to 15 to 20 years due to the problems with rust. Plastic and fibreglass tanks last about 30 years, while concrete tanks can last for more than 40 years.
How much does it cost to have a septic tank replaced?
This depends on the material, where you live in the country and any other work that needs to be done on installation. Average total purchase and installation costs vary from about £2800 to £4500. Remember, there might be more costs depending on whether the infrastructure needs to be upgraded.
How often should a septic tank be emptied?
This depends on how much the tank holds and how many people live in your house. On average it’s a good idea to empty it about once a year. If you live on your own, you may get away with once every two years.
Can I empty my own septic tank?
If you are a registered waste haulier, then possibly yes. Otherwise, no you can’t.
In the UK, only registered and certified carriers who comply with the Environment Agency’s regulations may carry hazardous waste. Sewage falls into this classification. Not only do you need special equipment, but you also have to have certified vehicles and a place authorised to receive your sludge.