What is Effluent? How UK Businesses Store and Manage Industrial Wastewater
Effluent is something every commercial and industrial business in the UK produces, yet it remains one of the most misunderstood and mismanaged aspects of operations. Whether you run a manufacturing plant, a farm, a food processing facility, or any other commercial premise, the wastewater your business generates is classified as effluent, and how you store, treat, and discharge it is governed by strict UK law.
Get it wrong and the consequences range from heavy fines to prosecution. Get it right and you protect your business, your local environment, and the communities that depend on clean water.
This guide covers what effluent actually is, the different types your business may produce, the UK regulations you must comply with, how the treatment process works, and how to choose the right effluent storage tank for your operation.
What is Effluent?
Effluent is liquid waste or wastewater that flows out from an industrial or commercial premise, a sewage treatment plant, or a sewer system. In simple terms, it is the outflow of any water that has been used in a commercial or industrial process and is no longer clean.
It is important to understand that effluent is not the same as the wastewater from your kitchen or toilet, which is classified as domestic sewage. Effluent refers specifically to trade and industrial liquid waste: the water generated as a byproduct of manufacturing, processing, cleaning, farming, or any other business activity.
Effluent can be either treated or untreated. Untreated effluent is raw liquid waste that still contains all of its original contaminants. Treated effluent has passed through a treatment process to remove harmful substances, making it safer to discharge. Crucially, even treated effluent must meet specific quality standards before it can legally enter a river, stream, lake, estuary, groundwater system, or the public sewer network.
What Are the Different Types of Effluent?
Not all effluent is the same. The type your business produces depends on your industry, your processes, and the nature of your site.
Trade Effluent
Trade effluent is the most common category for UK businesses. Under the Water Industry Act 1991, it is legally defined as any liquid waste, other than domestic sewage or surface water, that is discharged from a commercial or industrial premise as a result of a trade or industrial activity.
If your business uses water as part of its process, for washing, cooling, rinsing, or any other purpose, the resulting wastewater is trade effluent. Before you discharge it into the public sewer, you must hold a trade effluent consent issued by your local water company.
Industrial Effluent
Industrial effluent is a higher-risk category produced by manufacturing, chemical processing, mining, and heavy industry. It typically contains a complex mix of contaminants including toxic metals, dissolved solids, suspended solids, chlorine compounds, gas byproducts, and chemical detergents, all of which require more intensive treatment before safe discharge.
Facilities that produce industrial effluent often require bespoke treatment systems. Butek Tanks' Landflex ES liner is specifically engineered for industrial effluent storage, offering excellent chemical resistance to petrochemicals, toxic metals, and process chemicals.
Agricultural Effluent
Agricultural effluent includes slurry, digestate, silage effluent, and liquid waste from livestock farming. It also encompasses fertilizer runoff and contaminated water from yard and building wash-down. Agricultural effluent is particularly damaging to surface water and groundwater if it escapes into watercourses, as it introduces high levels of nutrients that deplete oxygen and destroy aquatic ecosystems.
In the UK, agricultural effluent storage and management is governed by the Silage, Slurry and Agricultural Fuel Oil (SSAFO) regulations, which set minimum standards for storage capacity, tank construction, and containment. Butek Tanks' slurry and digestate storage tanks are manufactured to meet these requirements, with Landflex ES lining as standard.
Domestic Sewage vs Commercial Effluent
Domestic sewage, which is wastewater from toilets, sinks, and kitchens in residential use, is handled differently to commercial and industrial effluent. Even if your business premise includes welfare facilities, the wastewater from those facilities is treated as domestic sewage, while the liquid waste from your production or processing activities is effluent subject to separate regulation.
What Does Effluent Contain? Common Contaminants
The exact composition of effluent varies significantly depending on the source, but it commonly contains one or more of the following:
- Suspended solids: particles of solid matter remaining in suspension in the liquid
- Dissolved solids: minerals and chemicals fully dissolved into the water
- Fats, oils, and greases (FOGs): common in food processing and catering waste streams
- Toxic metals and heavy metals: produced by manufacturing, electroplating, and mining operations
- Chemicals and detergents: from industrial cleaning and surface treatment processes
- Chlorine compounds: from disinfection and water treatment activities
- Gas byproducts: including hydrogen sulphide, which is toxic and corrosive to sewer infrastructure
- Fertilizer compounds: nitrogen and phosphorus from agricultural runoff
- Contaminated water: carrying pathogens, bacteria, and biological material from sewage treatment processes
Why is Untreated Effluent Dangerous?
Environmental Damage
When untreated liquid waste enters rivers, streams, lakes, or estuaries, it introduces harmful substances into ecosystems that are not equipped to cope. Suspended solids reduce light penetration and smother riverbeds. Nutrients from fertilizer and sewage compounds trigger algal blooms that deplete oxygen and devastate fish populations and plant life.
Groundwater contamination is particularly serious because it affects drinking water reserves used by entire communities and is extremely difficult to remediate once it occurs.
Public Health Risks
Effluent that is not properly treated and controlled represents a direct threat to human health. Contaminated water sources can spread waterborne diseases, and communities that rely on rivers, reservoirs, or groundwater for their supply are directly at risk.
Infrastructure Damage
Corrosive chemicals and detergents degrade sewer pipes and infrastructure. Suspended solids and fats cause blockages. Gas byproducts such as hydrogen sulphide corrode metal pipework. The cost of repairing sewer infrastructure damaged by non-compliant effluent discharge runs into millions of pounds each year across the UK.
UK Regulations - What Every Business Must Know
Trade Effluent Consent (Water Industry Act 1991)
If your business discharges trade effluent to the public sewer network, you must hold a trade effluent consent issued by your local water and sewerage company. This consent controls what you can discharge, in what quantities, at what flow rate, and at what times. Operating without one is a criminal offence.
Environment Agency Permits (Discharging to Watercourses)
If your effluent needs to discharge directly to a river, stream, lake, estuary, or into groundwater, you require a permit from the Environment Agency in England, or Natural Resources Wales. The Agency offers a standard permit for lower-risk activities and a bespoke permit for more complex cases such as industrial effluent containing toxic metals or unusual chemical compositions.
Consequences of Non-Compliance
The Environment Agency can issue enforcement notices, suspend operations, impose financial penalties running into hundreds of thousands of pounds, and pursue criminal prosecution for the most serious cases. A breach can also cause lasting reputational damage to a business and harm relationships with customers and investors.
The Effluent Treatment Process Explained
Primary Treatment
The first stage focuses on removing the largest solid particles and suspended solids through screening and sedimentation. Primary treatment typically removes around 60% of suspended solids from raw wastewater.
Secondary Treatment
Secondary treatment uses biological processes to break down dissolved organic matter that remains after primary treatment. The most widely used method is the activated sludge aeration process, in which microorganisms are introduced to the effluent in an aeration tank where they consume and break down organic contaminants. This process removes more than 90% of suspended solids and dramatically reduces biological oxygen demand (BOD), making the effluent far less harmful to aquatic environments.
Secondary treatment forms the foundation of systems such as Butek Tanks' Modular Wastewater System (MWS), which can be installed and operational within 7 to 20 days.
Tertiary Treatment
For effluent that must meet the highest discharge standards, tertiary treatment includes UV disinfection, filtration through specialist media, and chemical treatment to neutralise heavy metals. It is also used when treated effluent is to be reused rather than discharged.
How UK Businesses Store Effluent Safely
Effective effluent management does not begin and end with treatment. Before effluent can be treated or discharged, it must be stored safely and securely. The right storage system is just as important as the treatment process itself.
Corrugated Steel Effluent Tanks
Our corrugated steel storage tanks are one of the most versatile and cost-effective solutions for effluent storage across commercial, industrial, and agricultural sectors. Unlike fixed concrete tanks, modular steel tanks can be configured to the exact capacity your operation requires, scaled up by connecting multiple units, and relocated if your needs change.
Single tank capacities range from 2m³ to 5,000m³. Tanks are manufactured from Magnelis coated steel, offering significantly greater corrosion resistance than standard galvanised steel, which is an important consideration when storing acidic or chemically active effluent.
Choosing the Right Liner
The liner is the most critical component of any effluent storage tank. Butek Tanks manufactures all liner kits in-house, ensuring impartial expert guidance on material selection:
- Landflex ES: for industrial effluent and slurry, with outstanding chemical resistance to petrochemicals and toxic metals
- Butyl rubber: the premium option for general effluent storage, offering excellent impermeability and a long service life
- EPDM rubber: a cost-effective alternative for less chemically aggressive effluent applications
- HDPE: standard in aquaculture and applications requiring frequent internal cleaning
- PVC: suited to commercial premises with straightforward trade effluent storage requirements
Tank Covers and Roof Kits
An uncovered effluent tank is exposed to rainfall, which can increase volume and risk overflow. It also emits odours that may breach environmental permits and creates a safety hazard on site. Butek Tanks' range of roof kits includes heavy-duty steel roofs and purpose-made covers that prevent contamination and odour release. All include lockable access hatches, and the Aqua-Float cover prevents up to 98% of evaporation.
What is a Modular Wastewater System (MWS)?
For businesses that need a complete sewage treatment plant rather than just storage, Butek Tanks' Modular Wastewater System is a uniquely flexible solution. It can be installed and operational in 7 to 20 days and configured to treat up to 1,000m³ of sewage per day.
The system works through a complete treatment cycle: coarse screening removes large solids, primary sedimentation settles suspended matter, aerobic digestion breaks down organic contaminants, a glass bead filter provides liquid separation, and UV or chlorination disinfection eliminates remaining pathogens. The result is treated water that is 99.99% pathogen-free and safe to discharge into an existing drainage system or watercourse.
The MWS operates on less than 15kW and can run without local infrastructure or utilities. It is particularly valuable for water companies managing planned maintenance, developers managing wastewater on construction sites, and organisations operating in remote locations.
Frequently Asked Questions About Effluent
What is the difference between effluent and sewage?
Sewage refers to the mixture of wastewater and waste matter from domestic toilets and drains. Effluent is specifically the liquid waste that flows out of a treatment plant, industrial process, or commercial premise. In UK law, trade effluent is defined separately from domestic sewage and is subject to different regulatory requirements.
Is it illegal to discharge trade effluent without a licence?
Yes. Discharging trade effluent to the public sewer without a trade effluent consent is a criminal offence under the Water Industry Act 1991. Discharging to surface water or groundwater without an Environment Agency permit is equally illegal.
Can effluent discharge directly into a river or stream?
Only if you hold the appropriate Environment Agency permit. Untreated effluent must never enter a river, stream, lake, estuary, or groundwater system. Even treated effluent can only be discharged to a watercourse if it meets the specific quality standards set out in your permit.
What size effluent storage tank does my business need?
The right size depends on your daily effluent production volume, how long you need to store it, and any regulatory requirements in your consent or permit. Our team offers free site surveys to provide a tailored recommendation.
Can steel tanks safely store industrial effluent?
Yes, when fitted with the correct liner. Corrugated steel tanks lined with Landflex ES or HDPE provide excellent chemical resistance to industrial effluent, including streams containing toxic metals, petrochemicals, and aggressive chemicals.
Conclusion
Effluent is an unavoidable byproduct of commercial and industrial activity, but the risks it poses are entirely manageable with the right knowledge and the right systems in place. Understanding what effluent is, how it is classified, and how UK law requires you to manage it is the foundation of responsible wastewater management.
At Butek Tanks, we have been designing and manufacturing corrugated steel storage tanks for over 60 years. From steel water tanks and liner kits to slurry tanks, roof kits, and the Modular Wastewater System, we offer a complete range of storage and treatment solutions for every type of effluent across every sector.If your business needs a reliable, compliant, and cost-effective way to store and manage its effluent, contact Butek Tanks today to arrange a free site survey.