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9 reasons to install a domestic sewage treatment plant

By: Andrew Baird on Nov 2, 2022

Perhaps you have a beautiful house in the countryside. It is detached from all the hustle and bustle of city life—which is what your family has enjoyed all these years. But there is one problem with isolation: you are not connected to the mains drainage network, meaning you are responsible for treating your own wastewater. However, most homes have ageing septic tanks, which contaminate groundwater supplies and surface water. Upgrading your system and installing a domestic sewage treatment plant will ensure compliance and future-proof your house.

Here are nine reasons to install a domestic sewage treatment plant.

1. Compliance with strict sewage discharge rules 

Homeowners are required to comply with the UK government’s 2020 General Binding Rules, which ensure systems are correctly installed and maintained. They also guarantee that a household's sewage does not contaminate the environment. Failure to comply with the guidelines can lead to a £100,000 fine.

While regulations vary depending on what part of the UK you live in, most do not permit septic tank effluent to be discharged into waterways. The Environment Agency's regulations mean that many people must upgrade or replace their existing systems. On-site sewage treatment plants are a better environmental solution than upgrading legacy systems. And they are also more robust systems that comply with current regulations and are very likely to comply with even more strict future regulations.

2. Easier to sell your home

Selling a property without complying with government guidance on small sewage discharge will make it extremely difficult to sell your house, or the buyer will likely offer a sum well under the asking price. You were legally obliged to have made the changes by January 1, 2022, so if you haven’t already made them and want to sell your house, acting now is crucial.

Your house likely uses an old septic tank to treat your wastewater, but replacing it with a small sewage treatment plant compliant with EN 12566-3 will add value to the property. Currently, environmental and intelligent upgrades are the two most significant changes homeowners can make to a property to increase its value.

3. More efficient than septic tanks

Wastewater from washing machines, sinks, showers, baths, and toilets flows into wastewater treatment solutions located underneath the ground. Solids settle at the bottom as sludge, and the liquid septic waste is discharged.

An entry-level wastewater treatment solution is the septic tank, some of which discharge this effluent directly into waterways; however, this has been prohibited. The liquid must now flow into a drainage field where microorganisms can treat it as it enters the ground.

On-site sewage treatment plants work similarly to septic tanks; however, they use a mechanical system to pump oxygen to the microorganisms, allowing them to treat effluent more effectively. This means the treated wastewater is of far higher quality than the water released from a septic tank; therefore, it can be discharged into flowing water. Sewage plants also help prevent blockages if wastewater is released into a soakaway.

4. Environmentally friendly 

On-site sewage plants offer the most environmentally friendly way of treating domestic wastewater—more than septic tanks. One important reason is that they do not omit ammonia, a harmful substance to nature and wildlife. After treatment, the non-polluting effluent discharged by sewage treatment plants removes around 95% of contaminants harmful to the environment.

Also, you can take advantage of the recycled water from the plant in your garden, saving huge quantities of fresh water. Using recycled water will alleviate water stress, reduce your carbon footprint, and save you money in the process. 

5. Built for modern life

They are specially designed to cope with increased effluent flows that are produced by modern houses. A good system will exceed the British Standard for small sewage treatment plants, the current EA regulations, and more stringent predicted future standards. 

6. Decreased long-term costs

Installing a domestic sewage treatment plant does have a high initial cost; however, in the long term, they are cheaper to run.

This is because a sound system that is CE marked, fully tested, and certified to EN12566-3 for small wastewater treatment systems may be run for 3 years without emptying, saving on frequent maintenance expenses. It should also come with an extensive tank warranty. Other sewage systems must be emptied more frequently, quickly adding to the running costs.

7. Reduced risk to human health

Septic tanks offer the lowest level of treatment preventing risk to human health, whereas domestic sewage treatment plants produce high-quality effluent post-treatment. This reduces the likelihood of potentially fatal diseases being spread into local water systems. And it means you do not need to worry about contaminating your land and groundwater as you will not be exposed to pathogens from weakly treated sewage.

8. Simple installation

Domestic sewage plants are easy to install and are good options for properties that have limited space. However, even if your property has ample space, sewage plants have many advantages over septic tanks and earlier systems: they are installed underground, they are discrete, and they produce minimal odours. 

Additionally, domestic sewage treatment plant installation is far more straightforward than installing a septic tank and starts working much more quickly. 

9. Potential to produce green energy

The purpose of sewage treatment plants is to separate solids and liquids to then discharge a clear liquid. However, not all of the solid can be converted to wastewater, which is why sludge builds up at the bottom of the plant and must be removed periodically during maintenance.

However, engineers are working on innovative ways to turn this sludge into something useful—a potential source of green energy.

It is likely that homeowners will be able to use this green bio-energy as part of a more sustainable system. This will further reduce costs, and sewage treatment plants will result in even fewer waste products.


Several high-profile cases have recently been of companies discharging sewage into UK waterways. While this is not the fault of UK homeowners, the UK Environment Agency is keen for everyone to keep our waterways clean—homeowners and businesses alike. This is undoubtedly positive for everyone; however, the cost of improving the environment is sometimes a bitter pill to swallow. 

A robust upgrade from a septic tank to a sewage plant has many benefits. Not only is it better for the environment, but it will future-proof your home and increase its future value. 

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Topics: Wastewater Treatment

Andrew Baird

Written by Andrew Baird

Andrew is WCS Environmental Engineering Technical Director. Andrew has worked for WPL (now a part of WCSEE) since 2006 and has nearly 30 years’ experience in the water and wastewater treatment industry. Andrew has a background in traditional engineering and technical business development and has worked on technical projects for BAE Systems, North West Water & Yorkshire Water to name a few. Andrews’s commercial awareness goes hand in hands with his excellent knowledge in industrial effluent treatment and broad knowledge of Europe’s water and wastewater treatment needs in manufacturing and process industries.

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