What is a grease trap?

A grease trap, also known as a grease interceptor or grease separator, is a specialised device designed to capture fats, cooking oils and grease (FOG) created by making hot food before these substances enter the main drainage system. Without a grease trap installed in kitchens, FOG can accumulate within pipework, solidify, and cause serious blockages. Over time, this can lead to slow wastewater flow, increased pressure on drainage infrastructure, and even sewage system overflows.

Grease traps function by allowing wastewater to cool and settle. As the temperature drops, heavier food solids sink to the bottom while lighter grease and oil rise to the surface. This separation process enables cleaner water to flow safely into the drainage system while trapping harmful FOG residues that would otherwise cause damage. Due to this continuous build-up of FOG, regular emptying and maintenance of grease traps is important.

What are the legal obligations for maintaining grease traps?

Businesses and institutions must comply with various standards that govern the management of the waste that accumulates in their grease traps. Regulations in England and Wales include:

Section 111 of the Water Industry Act 1991

Section 111 of the Water Industry Act 1991 makes it a criminal offence to discharge any matter into public sewers that may interfere with their operation, cause damage or obstruct flow. This includes FOG from commercial kitchens, which can accumulate in drainage systems, leading to blockages, sewer overflows and infrastructure damage.

Businesses that fail to prevent grease waste from entering the sewer network may face legal enforcement from water authorities, including fines of up to £50,000 in Magistrates’ Court or an unlimited fine if prosecuted in the Crown Court. Persistent non-compliance can also lead to prosecution under environmental laws or business closure orders if grease-related blockages pose a risk to public health or the environment.

To comply with Section 111, businesses must implement effective grease management systems, including the installation and regular maintenance of grease traps. Water companies may carry out inspections and require businesses to demonstrate that they are taking reasonable steps to prevent grease from entering public sewers.

The Environmental Protection Act 1990

This act imposes a legal duty of care on businesses to manage all waste, including grease waste, in a manner that prevents harm to human health and the environment. Under this legislation, businesses must store and transport waste securely using authorised carriers such as Universal Tankers, who will dispose of the FOG at licensed facilities.

Food Safety Act 1990

The Food Safety Act 1990 sets out food hygiene regulations that food businesses must follow to protect public health. This includes the safe handling and disposal of kitchen waste, such as grease and food by-products. Accumulated grease can lead to unsanitary conditions, foul odours and pest infestations, which pose a risk to food safety. Environmental health officers have the authority to inspect premises and issue enforcement notices if poor grease management is identified. Repeated non-compliance can result in fines, legal action, or even business closure.

How often should a grease trap be cleaned?

The frequency of grease trap cleaning depends on the volume of wastewater processed, the type of food prepared, and the size of the trap. Industry guidance recommends servicing grease traps at least every four to six weeks to prevent excessive FOG accumulation. However, high-traffic establishments, such as restaurants, fast-food outlets, and large-scale catering facilities, may require more frequent cleaning to maintain efficiency and compliance with grease trap cleaning regulations.

Proper grease management systems incorporating cleaning at appropriate intervals will reduce the likelihood of blockages, unpleasant odours and drainage system failures.

What are the risks for those failing to adhere to grease trap regulations?

Failure to comply with grease trap regulations can result in severe legal, financial and operational consequences for businesses. Under Section 111 of the Water Industry Act 1991, allowing FOG to enter the drainage system unlawfully is a criminal offence. Business owners and managers found responsible for sewer blockages may face prison sentences of up to five years for offences linked to environmental harm under the Environmental Protection Act 1990.

Regulatory bodies, including local authorities and water companies, are empowered to conduct inspections and issue enforcement notices where non-compliance is identified. If a business repeatedly fails to meet grease management standards or ignores official warnings, authorities can order a forced closure until the necessary improvements are made. Additionally, businesses operating in the food and hospitality sector may risk revocation of their food hygiene rating, leading to reputational damage and loss of customers.

Beyond legal penalties, failing to maintain grease traps can cause costly drainage system failures, flooding and damage to public sewer infrastructure. Water companies have the right to recover the costs of repairs and clean-up operations from businesses responsible for the issue, further increasing financial liabilities.