Septic Tank Costs: How Much Should You Expect to Pay?

While those living in urban centres often take their tax paid sewer systems for granted, those living in the countryside understand how crucial septic tanks are.

With no sewer system, all the liquid waste has to drain somewhere, and the only safe way is with a septic tank. Though it’s a necessity in rural locations, a well-maintained and correctly installed system can actually work out cheaper than paying into public sewage works.

Despite this, the upfront costs can be daunting. There is a myriad of factors that can affect septic tank prices, including: whether it’s above or below ground; labour costs; the size of the tank; its location; and, most importantly, the material.

With all of these to consider, trying to find the right septic tank for your needs and budget can be a real drain. But have no fear, we’re at your disposal! This guide will help you learn everything you’ll need to know about the costs involved with installing a septic tank.

So, how much will different septic tanks set you back?

Other than labour costs, the material you use will have the biggest impact on the cost of your septic tank. Your first instinct might be to investigate cheaper materials, which will certainly lower the cost initially. But this might not always be the best option.

For instance, septic tanks made from concrete will be quite inexpensive. However, lower quality materials will have a shorter life span and may require more maintenance costs than a more expensive tank. If you can afford the initial costs, it can be worth paying a little extra for high quality materials, depending on your needs and timeframe.

Having said this, each material does come with its own advantages and disadvantages that should be considered.

Concrete Septic Tank

This is easily the most used material for a septic tank. As mentioned, it’s one of the cheaper materials to use, but unlike other budget options, concrete can be surprisingly durable. The low price means that concrete is a good choice for very large capacity tanks and, assuming its well maintained, a concrete septic tank can last around 30 years.

Despite these advantages, the weight of the material and equipment required for the installation can cause complications on sites that are hard to access. It can also raise labour costs in some cases. Cost wise, the worst part of concrete tanks are their maintenance costs. They will need to be cleaned and maintained at a higher frequency than alternate materials, and they’re also more likely to crack or leak. So, while the upfront costs are lower, in the long term it can prove more expensive. As they say, you get what you pay for.

You could expect a concrete septic tank to cost between £700 – £1300.

Plastic Septic Tank

When we say plastic, for septic tanks we usually mean polyethylene or polypropylene. Like concrete, this is a very economical material to use, but has some advantages over concrete. It’s a much lighter material, allowing for use on hard to access sites and reduced labour costs. In many ways, plastic septic tanks are also easier to maintain, as there’s no need to worry about corrosion or rust.

However, they aren’t typically available in large sizes, and can be a lot more finicky to install. Plastic septic tanks have a limited depth of installation and very specific installation requirements to ensure effectiveness.

Expect to spend between £600 – 1500 on a plastic septic tank.

Fibreglass Septic Tank

Fibreglass Reinforced Plastic is essentially a higher quality version of a plastic tank, having much the same advantages and fewer of its disadvantages. For example, they’re much lighter than heavier material tanks like concrete, making installation much easier. They are also more durable. You won’t have to worry about the tank cracking in extreme conditions or whether it is prone to leakage like concrete tanks.  

Fibreglass septic tanks also last a lot longer than its polyethylene equivalent – a well-controlled tank can last up to 50 years.

The trade-off to this is a much higher price point, at around £1000 – £2000.

What will it cost to install a septic tank?

While we’ve touched on this already, it’s worth reiterating that there are many factors that will affect the cost of your septic tank – installing the tank is no different. The two biggest contributors will be the size of the tank and whether it will be installed above or below ground.

In terms of size, the larger a tank is, the longer you can expect installation will take. A small tank will have an average cost of £1500, while a larger one could cost up to £3000.

But if you’ll be installing the tank above ground, these figures could easily half. Similarly if you’re replacing a septic tank or installing one where one was, the costs will be considerably reduced. Compared to installing one for the first time, reinstalling a tank is much more straightforward as there’s no need to excavate a large area or lay foundations.

What’s the cost of emptying a septic tank, and how often should you do it?

As a septic tank separates wastewater of any solid contaminants, sludge and slum will steadily build up. Eventually, this will need to be removed by a qualified professional.

The costs involved with emptying a septic tank can vary wildly, depending on size of the tank, the type of tank (especially if its single or multi chambered), its location on the site and how deep in the ground it’s placed. The range you can expect is anywhere between £90 – £300.

As with everything else mentioned, how often you empty your tank will be different for everyone. Larger households will naturally need to be emptied more frequently.  As a rule, you should look to empty your tank every year, but could stretch to two or potentially even three if you live on your own.

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!