Last reviewed 10 February 2020

Found lurking in the sewer network, fatbergs are an unpleasant and costly problem. Laura King looks at how these congealed masses form and what food establishments should be doing about it.

Fatbergs. They’re the subject of TV shows and one even has its own museum exhibition. Our innate fascination with the disgusting — most probably as an adaptive behaviour for avoiding disease — helps explain this unlikely celebrity. However, fatbergs, or more precisely the contents of fatbergs, are also attracting increasing regulatory attention.

Fatbergs are large masses of solid waste found blocking the sewage system. They are created when “unflushables” (things that should not be flushed down the toilet such as wet wipes, sanitary products or cotton wool) get caught up in congealed fats, oils and grease (FOG).

The sewer network is not designed to cope with this sticky combination, and the result is somewhat staggering. The UK’s largest fatberg — the infamous Whitechapel fatberg — was discovered in London in 2017. It measured more than double the length of two football pitches and weighed approximately the same as 11 double decker buses. The fatberg attracted mass media attention, and was even christened, by public vote, Fatty McFatberg.

As well as causing issues such as local flooding, as might be expected removing fatbergs is not an easy, or agreeable task. The Whitechapel fatberg took several weeks to clear, with teams digging out the coagulated mass with the use of high-powered water jets. While arguably this is not a job that anyone would want to repeat, unfortunately the Whitechapel fatberg is not an isolated incidence. For example, in 2019 a 40-tonne fatberg was found in Greenwich and, at the beginning of the year, a fatberg 64m in length was found near Sidmouth in Devon.

Blockages such as these are completely avoidable if fats and unflushables are disposed of properly — and so it is no wonder that water companies are stepping up action to avoid fatbergs from occurring in the first place.

Fatbergs and commercial kitchens

Although unflushables are one half of the issue, FOGs from domestic and commercial properties are the other critical ingredient in these problematic blockages. And although domestic properties play their part, commercial kitchens are undoubtedly key culprits that ought to be doing better.

For example, visits from Thames Water officers to the food outlets in Whitechapel Road — home of Fatty McFatberg — found that none had proper systems in place to stop FOG from being poured down the sink. Indeed, visits in 2017 by Thames Water officers to over 700 food establishments in London found that a staggering 92% were failing to prevent FOGs and food waste entering the sewage network.

This is despite the proper disposal of FOG being a requirement by law under regulations that span environmental requirements, food safety and the built environment.

Fatbergs and the law

The plethora of legislation written to protect us and the environment from the improper disposal of waste means that there are several pieces of legislation that can be used to enforce against the disposal of FOGs down the drain.

Section 111(1) of UK Water Industry Act 1991, for example, states that nobody shall throw or empty “any matter likely to injure the sewer or drain, to interfere with the free flow of its contents ...”. Although this is fairly broad in its description, it includes grease. Under the Water Industry Act, water companies can claim compensation from offending companies if they can be identified as having caused a blockage. Other enforcement can include fines and imprisonment.

Local authorities also have powers under the Food Safety Act 1990 (FSA) and Environmental Protection Act 1990 (EPA). Under the FSA, officers from environmental health departments can act if problems are found with grease management systems in commercial kitchens.

From an environmental viewpoint, under s.34 of the EPA, establishments need to comply with their duty of care and properly dispose of waste (including waste FOGs from cooking) using licenced waste providers. Furthermore, under s.79 of the EPA, any waste causing problems such as unwanted smells could be considered a “statutory nuisance”. In the extreme, this could result in a business being shut down while improvements are made.

In addition, the use of proper equipment to trap FOGs is a requirement of the Building Regulations Part H (Drainage and Waste Disposal).


The legislation is clear, and where establishments are identified as causing a problem, action is taken. Although, in most instances, officers will work with establishments to make changes, a handful of prosecutions have been successfully made against companies that have failed to adopt proper practices.

For example, last year, Severn Trent Water successfully prosecuted a Nottingham-based restaurant for causing multiple sewer blockages resulting in flooding in the area. The restaurant was ordered to pay over £8000 in fines, including costs and a victim surcharge.

Following the case, Grant Mitchell, sewer blockages lead, commented: “The verdict in this case is an important milestone for us, and we really want this to make other companies think about what they are doing with regards to disposing of fats, oils and grease and how it impacts our customers”. He went on to say: “We clear around 45,000 blockages a year and fat contributes to the majority of those … This is totally avoidable, and in this case, simply installing a suitable grease trap and making sure it’s maintained could have prevented the situation.”

“Legal action is always a last resort for us, but our customers and the environment shouldn’t have to suffer because of the actions of one business not following the rules and ignoring our advice.”

FOG guidance

Extensive guidance exists to help organisations manage FOG responsibly. This can often be obtained from water companies directly, who may offer a free site visit, or local authority environmental health departments. In general, however, the following advice can be applied to any commercial kitchen.

  • Make sure any leftovers from plates are scraped into the bin before they are washed up.

  • Use strainers to capture any food waste.

  • Install equipment that will prevent FOG reaching the waste pipes. A specialist contractor will be able to identify the best solution for your kitchen, but options include equipment such as grease traps or grease inceptors. Ensure that you are aware of the correct procedure for emptying and maintaining any equipment installed.

  • Store waste oil in an airtight container. Keep the container away from drains in case there is a spillage or leak.

  • Dispose of waste oil properly. This means that it will need to be collected by an organisation that is licenced by the Environment Agency.

  • Keep records of the waste transfer notes provided when the waste is collected.

  • Make sure staff are trained in how to dispose of FOGs and any requirements for maintenance.


  • Fatbergs are the result of unflushables, such as wet wipes and sanitary products, getting caught in congealed fats oils and grease (FOGs). The resulting mass blocks the sewers causing problems such as flooding in the local area.

  • Fatbergs are a serious and costly problem and, as a result, water companies and local authorities can act against establishments who do not manage FOGs properly.

  • Initially, authorities and water companies will offer advice; however, if advice is not followed then offending companies can face prosecution.

  • Guidance on how to manage FOGs can be provided by environmental health departments and water companies. However, scraping plates before they are washed up and installing a fat trap or interceptor are two key actions to take. It is also important to dispose of waste oils properly and make sure staff are trained.