CLEARMASTERS
in drainage
levels first
Regulations
and reinstate
for aftercare
The basics
Why install a treatment plant?
A sewage treatment plant treats the waste from your property where there’s no mains sewer. Unlike a septic tank, which only settles the solids, a treatment plant pumps air through the wastewater so bacteria can break it down, and the water that comes out is clean enough to go to a drainage field or, where the rules allow, a stream or ditch.
Once your plant is in, we can look after it with yearly treatment plant servicing and desludging. If the plant discharges to ground, we can also put in a new drainage field.
We do this work across Surrey, West Sussex, East Sussex, Kent, Hampshire and London, with tankers and engineers in each area most days.
In England, a septic tank must not discharge straight to a watercourse. Those that did had to be replaced or upgraded by 1 January 2020, or sooner if the property was sold. A treatment plant is usually the answer, and it’s also the standard choice for new off-mains homes.
We install plants for single homes, groups of houses and commercial sites, from survey and design through to commissioning.
Step by step
How a treatment plant is installed
Step through a typical installation, or let it play. Tap a step to jump to it.
Quick checker
Does your septic tank need replacing?
Answer a few questions for a quick idea of whether your current system is likely to meet the General Binding Rules in England.
If it drains to a ditch, stream or river, it almost certainly needs upgrading. Other systems may be fine, or may need work on the drainage field rather than a new plant. A survey will tell you for certain.
A quick guide to the Environment Agency’s General Binding Rules for England, not a legal assessment. A survey will tell you for certain.
Compared
Septic tank, treatment plant or cesspit?
The three main off-mains options, side by side.
| Septic tank | Treatment plant | Cesspit | |
|---|---|---|---|
| How it works | Settles solids; the liquid is treated in the ground | Treats the wastewater with air and bacteria | Holds everything; nothing leaves |
| Where it can discharge | A drainage field only | A drainage field, or a watercourse under the rules | Nowhere: it must be emptied |
| Needs power | No | Yes, for the blower | No, apart from any alarm |
| Emptying | Usually once a year | Usually once a year | Often every few weeks |
| Servicing | Inspection | A service at least once a year | Alarm and tank checks |
| Best for | Existing systems with a working drainage field | New homes, upgrades and discharge to watercourses | Where no discharge is possible |
Types of plant
Which type of treatment plant?
Most domestic plants fall into one of these types. We’ll recommend one that suits your site, your occupancy and where the water can go.
Activated sludge
Air bubbles keep the sewage and bacteria mixed. Compact and effective, and common in homes.
Submerged aerated filter
Bacteria grow on fixed plastic media while air is blown through. Robust and very widely used.
Moving bed
Bacteria grow on small floating media that tumble in the aerated chamber.
Sequencing batch reactor
Treats the water in timed batches in one chamber. Good with changing flows.
Rotating biological contactor
Slowly turning discs carry the bacteria through the sewage and the air. Low energy.
Package plants
Larger pre-built plants for groups of houses, holiday parks and commercial sites.
Cost
What affects the cost of a treatment plant installation?
Every site is different, so we quote after a survey. These are the things that make the biggest difference.
| Factor | Why it matters |
|---|---|
| Size of plant | Sized for the number of people or the flow it serves, including peak flows. |
| Ground and access | Rock, clay, a high water table or tight access for machinery all add time and cost. |
| Where the water goes | A new drainage field is a big part of many jobs. Discharging to a watercourse needs a suitable outfall. |
| Levels | If the plant can’t drain by gravity, a pump will be needed on the way in or out. |
| The old system | Emptying, removing or filling in an old septic tank or cesspit. |
| Approvals | Building Regulations fees, and an Environment Agency permit if the rules can’t be met. |
After installation
Looking after your new plant
Why Clearmasters
Why choose Clearmasters?
We service and empty treatment plants of every major make, every day. That tells us which plants suit which sites, what goes wrong when a plant is badly installed, and how to install one so it keeps working.
Ask us a questionWe survey before we dig
Levels, ground conditions, buried services and where the water can go, checked before we quote.
Done to the rules
Designed and built to the Building Regulations, British Standards and the manufacturer’s instructions.
We look after it afterwards
We empty, jet, survey and service what we install, so you have one firm for the life of the system.
Trained engineers
Our engineers hold current confined space entry certificates and carry the most common parts.
What our customers say
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Questions answered
Treatment plant installation FAQs
Do I have to replace my septic tank?
If it discharges straight to a ditch, stream or river, yes: it should have been replaced or upgraded by 1 January 2020. If it drains to a working drainage field, it may meet the rules as it is. Try the checker above, or book a survey.
Where can a treatment plant discharge?
To the ground through a drainage field, or to a watercourse where the General Binding Rules allow. Discharges over 2,000 litres a day to ground or 5,000 litres a day to surface water need an Environment Agency permit.
Do I need planning permission?
A new plant generally needs Building Regulations approval. Planning permission isn’t usually needed for a domestic plant, but it can be for larger or commercial plants or in sensitive locations. We’ll check what applies to your site.
How long does installation take?
Most domestic plants take a few days, depending on the ground, the access and whether a new drainage field is needed. Larger and commercial plants take longer.
Does a treatment plant need electricity?
Most do, to run the air blower or pumps. A typical domestic blower is rated somewhere around 40 to 100 watts and runs all the time, so check the running cost when comparing makes.
What happens to my old septic tank?
It’s emptied, then usually removed or broken up and filled in. Sometimes it can be reused, for example as a rainwater tank.
How often does a treatment plant need servicing?
Most manufacturers ask for a service at least once a year, plus emptying when the sludge builds up. See our treatment plant servicing.
Got a different question? Call 03333 233566 or send us a message. You can also read the rules on GOV.UK.
Related services
Fully accredited & compliant
We're independently vetted and certified so you can trust who you're letting onto your site.
SafeContractor
Health & safety pre-qualification accreditation, verifying our processes meet recognised safety standards.
RISQS
Railway Industry Supplier Qualification Scheme — approved to work safely within the rail industry supply chain.
Achilles UVDB
Utilities Vetting Database membership, confirming we meet the utilities sector's supply chain standards.
Trading Standards Approved
Vetted and approved under the local authority's trusted trader scheme for honesty and fair dealing.
NADC Member
Members of the National Association of Drainage Contractors, the UK trade body for the drainage industry.
Registered Waste Carrier
Registered with the Environment Agency, so your waste is handled and disposed of fully within the law.