Every commercial kitchen in the UK generates fats, oils and grease. Left unmanaged, that waste inevitably ends up lining pipes, feeding fatberg formation, and creating the kind of blockages that shut down kitchens and flood streets. This guide covers exactly how restaurants, takeaways, pubs, schools and hospital kitchens can prevent fatbergs through proper grease management, compliant drainage systems and regular maintenance.
Key Takeaways
- Fats, oils and grease from commercial kitchens are the primary cause of fatbergs and blocked drains in UK sewer systems, with 28,062 blockages cleared in 2024 due to FOG alone.
- Restaurants, takeaways, pubs, school canteens and hospital kitchens must use correctly sized and well-maintained grease traps to prevent fatbergs and comply with regulations.
- Trent’s Drains provides 24/7 grease trap servicing, drain unblocking and CCTV surveys for commercial kitchens across Bristol, Bath, Gloucester, Cheltenham, Swindon and the wider South West.
- Regular maintenance and staff training deliver significant cost savings compared to emergency call-outs, regulatory fines and reputational damage from flooding or sewer overflows.
- This article explains practical steps to remove fats before they reach the drain, how to design a compliant grease management system, and how Trent’s Drains can help arrange a preventative maintenance plan.
What Are Fatbergs and Why Should Restaurants Care?
Fatbergs are massive blockages caused by the accumulation of fats, oils, and grease combined with wet wipes, sanitary products and other debris inside sewer systems. They form rock-like masses that can grow to extraordinary size. The Whitechapel fatberg discovered in London in 2017 measured 250 metres long and weighed approximately 130 tonnes. In 2021, a fatberg the size of two blue whales was found in Southend-on-Sea, where engineers removed around 200 tonnes of waste from sewer pipe networks.
A single busy commercial kitchen can discharge dozens of litres of FOG per week through frying, roasting, sauces, dairy and plate scrapings. That volume might seem manageable at the sink, but it accumulates downstream into fatty deposits that build up inside pipes and public sewers. Across the UK, approximately 28,000 blockages are cleared annually due to grease build-up, costing the water industry close to £200 million per year.
Fatbergs can lead to foul odours, slow draining sinks, and sewer flooding. For a restaurant, that means sewage backing up into the kitchen, emergency school closures at nearby premises, forced closure by environmental health, and the kind of disruption that damages reputations. Water companies and local authority teams are increasingly tracing FOG sources back to individual food businesses, with potential fines and clean-up charges passed directly to the responsible premises.
How Fats, Oils and Grease From Commercial Kitchens Create Blocked Drains
When hot liquid grease is poured down the sink, it cools and solidifies in the pipes. This process is unavoidable: FOG enters drainage systems as warm liquid from cooking processes and dishwashing, but as wastewater flow slows or temperature drops in external pipework, fats congeal on pipe walls. Older drainage systems common in city centres like Bristol and Bath, with narrow diameter pipes, shallow gradients and rough surfaces, are particularly vulnerable.
The main FOG sources in a commercial kitchen include:
- Frying oils and deep-fryer waste
- Meat fats and roasting juices
- Dairy residues, gravies and sauces
- Food waste scrapings from plates, pans and trays
- Residues from dishwashers and mop water
The typical route runs from sink or dishwasher through internal plumbing, into external drains, then on to the public sewer system. Fatty deposits start forming wherever flow slows or pipes cool. Hot water does not dissolve grease; it pushes it further down the line into public sewers where it re-solidifies and contributes to fatberg formation.
Combined sewer systems in older parts of Gloucester, Cheltenham and other South West towns are particularly vulnerable to FOG-related flooding during severe weather and heavy rain, as surface water combines with sewage already compromised by grease blockages.
Grease Traps: Your First Line of Defence Against Fatbergs
A grease trap is a device installed in kitchen wastewater drainage that separates fats, oils, and grease from wastewater before it enters sewers. It works by slowing the flow of water through internal baffles, allowing FOG to float to the surface while solids settle to the bottom. Cleaner water then exits through the outlet.
The main types relevant to restaurants and commercial kitchens include:
| Type | Best For | Typical Capacity |
|---|---|---|
| Under-sink passive traps | Small cafés, coffee shops, light prep kitchens | 50–115 litres |
| In-line interceptors | Full-service restaurants, pubs, takeaways | 190–300 litres |
| External underground separators | Hotels, hospitals, large-scale catering | 700–1,100+ litres |
| Automatic Grease Removal Devices | High-output kitchens needing continuous separation | Varies by model |
| Automatic Grease Removal Devices can actively separate fats from wastewater using skimmers and heated surfaces, maintaining high efficiency without manual intervention between services. |
Correctly sized grease traps are required under UK Building Regulations Part H and water company trade effluent rules for food-serving premises. Grease traps help prevent costly plumbing issues and fatbergs, protect internal pipework, and reduce the risk of enforcement action and insurance complications after overflows.
Choosing the Right Grease Trap for Your Commercial Kitchen
Selecting the right trap requires looking beyond catalogue specifications. Key sizing factors include:
- Number of covers served per day
- Type of cuisine (heavy frying generates far more grease than light prep)
- Number and size of sinks and dishwashers
- Peak service times and flow rates
Site the trap as close as possible to FOG sources while allowing safe access for regular maintenance, cleaning and waste removal vehicles. New builds in Bristol, Bath and Swindon should integrate grease trap capacity into drainage design from the outset, while older premises may need compact or retrofit solutions.
Rather than guessing, investing in a professional site assessment is the most effective system for getting it right. Trent’s Drains can visit your site, assess your current setup, and recommend an appropriately sized and compliant grease trap that will genuinely help prevent fatbergs.
Grease Management Best Practice: Removing Fats Before They Reach the Drain
The best grease trap in the world will struggle if your kitchen is sending maximum FOG down the drain. These daily and weekly habits reduce load at source and extend service intervals:
- Dry scrape first. Dry scraping all dishware removes debris before washing. Use spatulas, scrapers or paper towels to wipe pans, roasting trays and plates into a bin before they reach the sink.
- Install sink strainers. Metal strainers on pot wash and prep sinks catch solid food waste and prevent it entering the drainage system. They cost almost nothing and save considerable trouble.
- Use food filters. In high-volume operations like school kitchens and hotel banqueting suites, inline filters between sinks and grease traps capture fine particles that would otherwise accumulate in the trap.
- Collect used cooking oil separately. Used cooking oils should never be poured down the sink. Set up labelled, lidded containers and store them safely. Arrange regular uplift by a licensed waste oil collector so oil is recycled responsibly rather than contributing to blockages.
- Dispose of food waste properly. Scrape plates into food waste bins, not into sinks or floor drains.
Improper grease disposal is a leading cause of fatbergs. Every litre of oil kept out of the drain is a litre that will never contribute to a blockage.
Staff Training and Kitchen Procedures
Good grease management lives or dies with the people on the line. Staff training is crucial for proper fat, oil, and grease disposal practices, and it needs to be simple, visual and repeatable.
- Add a short induction module for new starters explaining what fatbergs are, why grease traps matter, and exactly how to scrape and sort waste. Whether someone is working at a city-centre restaurant or a child’s school canteen, the principles are the same.
- Put clear signage above every sink and dishwasher reminding staff not to pour fats, oils and grease down drains and to use strainers and scrap bins. Parents and pupils at a school expect the kitchen to maintain clean, safe practices; so do diners at any restaurant.
- Create a daily and weekly checklist covering grease trap inspection, bin lids, used oil storage, and cleaning of strainers and filters. Feed this into your existing kitchen management routines.
Trent’s Drains engineers can walk kitchen teams through best practice during a maintenance visit, reinforcing correct procedures on site and providing practical tips and advice tailored to your layout.
Regular Maintenance: Keeping Grease Traps and Drains Working Properly
Even the best grease trap will fail if not emptied and cleaned on a suitable schedule. Improperly maintained grease traps can allow fats to bypass and enter drainage systems, leading to the very blockages they were installed to prevent. Regular maintenance prevents grease traps from overflowing and keeps them functioning as designed.
Cleaning grease traps every 3–4 months is recommended for optimal performance. Busy restaurants and takeaways with high FOG output may need servicing every 1–3 months. Hotels, schools and care homes should service at least quarterly, depending on trap size and the range of food prepared.
What maintenance should include:
- Measuring FOG depth (the 25% rule: when grease plus solids reach 25% of liquid depth, the trap needs emptying)
- Removing all fats and solids
- Checking baffles and seals for damage
- Inspecting connecting pipework and access covers
- Ensuring inlet and outlet flow is clear
A preventative maintenance contract with Trent’s Drains covers scheduled visits and priority emergency support for sites across Bristol, Bath, Gloucester, Cheltenham, Swindon and the broader South West. Cleaning your grease trap regularly on a managed schedule is always cheaper than reacting to an emergency.
CCTV drain surveys can be used annually or after repeated slow-drain issues to check for early fatberg formation or structural problems in your pipes before they become major failures.
Recognising Early Warning Signs of Fatberg and Grease Problems
Kitchen managers and facilities teams should monitor for these symptoms during daily checks:
- Sinks and dishwashers draining slowly or failing to empty fully
- Gurgling pipes during or after water systems are in use
- Recurring bad smells around floor drains, grease traps or mop areas, creating unhygienic conditions
- Grease trap filling faster than expected between scheduled cleans
- External indicators like raised or overflowing manhole covers in yards or car parks, especially after rain
These signals suggest FOG is beginning to accumulate and blockages may be forming. You might hear announcements on local radio stations about sewer flooding or closure information linked to fatberg-related incidents. If you notice any of these at your premises, don’t wait for a full blockage.
Contact Trent’s Drains for a same-day investigation in Bristol, Bath, Gloucester, Cheltenham, Swindon and nearby South West locations. Intervening early avoids disruption to service, reduces the duration of any closure, and eliminates the need for extensive jetting or excavation work.
Compliance, Environmental Responsibility and the Cost of Getting It Wrong
Good grease management is not just best practice. It is a legal requirement for commercial kitchens. Regular professional servicing of grease traps is required to comply with regulations under several pieces of UK legislation:
- The Water Industry Act 1991 makes it an offence to discharge trade effluent (including FOG) into public sewers without consent or in breach of consent conditions.
- Building Regulations Part H requires drainage serving hot food premises to include grease separators complying with BS EN 1825.
- The Environmental Protection Act 1990 addresses pollution of water systems and watercourses, relevant where fatbergs cause combined sewer overflows.
Water companies in regions including Bristol and the wider South West can recharge businesses for the cost of clearing FOG-related blockages traced back to specific premises. That means the cost of someone else’s cleanup could land on your page of accounts.
The business impacts of ignoring grease traps and fatbergs extend beyond costly repairs. Enforced closure by environmental health officers, negative coverage in local press and on social media, and lost bookings can lead to long-term reputational environmental damage that is hard to recover from. Fatbergs disrupt wastewater flow and can lead to environmental contamination of rivers and coastal waters.
The positive side is clear. Installing and maintaining a compliant grease management system with Trent’s Drains reduces long-term drainage costs, ensures compliance, and helps protect the environment across the South West. The benefits far outweigh the investment.
How Trent’s Drains Supports Restaurants and Commercial Kitchens Across the South West
Trent’s Drains is a family-run drainage specialist offering both emergency and planned services to commercial kitchens of all sizes. Whether your job is running a single pub kitchen or managing multiple school or hospital sites, Trent’s Drains can help.
Core services for preventing fatbergs include:
- 24/7 emergency drain unblocking and high-pressure water jetting
- CCTV drain surveys to assess pipe condition and identify early FOG deposits
- Grease trap installation, servicing and emptying
- Preventative maintenance contracts with scheduled visits
- Guidance on compliance with trade effluent consents and building regulations
Trent’s Drains serves Bristol, Bath, Gloucester, Cheltenham, Swindon and surrounding towns and rural locations across the South West of England.
A typical engagement starts with an initial site visit, followed by a drainage and grease trap assessment, recommendations for any upgrades, and agreement of a tailored maintenance schedule. Multi-site businesses can save time and money by consolidating their drainage needs under a single coordinated plan.
Contact Trent’s Drains for a no-obligation survey to review your current grease management setup and identify improvements that will help prevent fatbergs and blocked drains at your premises.
FAQs: Restaurant and Commercial Kitchen Drainage & Fatberg Prevention
How often should our restaurant grease trap be emptied?
Most busy restaurants and takeaways need grease trap servicing every 1–3 months. Lower-volume sites may be able to stretch to quarterly. Cleaning grease traps every 3–4 months is essential to prevent blockages, but actual frequency depends on trap size, FOG output and type of cuisine. Trent’s Drains can monitor FOG levels over a few cycles at your site in Bristol, Bath, Gloucester, Cheltenham, Swindon or the wider South West to set an optimal schedule that keeps your system working and avoids emergency call-outs.
Can enzyme or bacterial dosing alone replace a physical grease trap?
Biological dosing systems can help break down fats, oils and grease inside pipework, but they are not a substitute for a correctly sized grease trap where one is required by regulations or building design. Use dosing as a complementary measure alongside physical grease traps, especially on long internal pipe runs or problem lines where FOG tends to form deposits between services.
What should we do in an emergency if our kitchen drains suddenly back up?
Stop using sinks and dishwashers immediately. Keep staff and customers away from affected areas to avoid unhygienic conditions, and do not pour chemicals down drains that could react with wastewater. Call Trent’s Drains for a 24/7 emergency response in Bristol, Bath, Gloucester, Cheltenham, Swindon and nearby South West locations. Engineers can clear the blockage safely, investigate the cause, and provide advice on preventing recurrence.
Do small cafés and coffee shops really need grease traps?
Even smaller premises can generate enough dairy fats, oils and food residues to cause drainage problems over time, particularly where cooking or baking happens on site. A professional assessment will determine whether a compact under-sink unit or another grease management solution is appropriate for your specific layout and menu. It is better to assess the risk early than to face a blockage that forces a closure during peak trade.
Can Trent’s Drains help multiple sites with a single maintenance agreement?
Trent’s Drains can set up coordinated preventative maintenance plans for groups operating several locations across Bristol, Bath, Gloucester, Cheltenham, Swindon and the wider South West. Multi-site agreements simplify scheduling, ensure consistent standards across every site, and often reduce overall drainage and grease trap servicing costs. Whether you operate a chain of restaurants or manage drainage for a local authority’s school kitchens, a single point of contact makes the whole process easier to maintain.
