Commercial Drainage Compliance in 2026: Part H, Grease Traps and What Environmental Health Officers Check

In the UK, different bodies can serve a notice about the same commercial drain. Building control cares how it was designed. Environmental health cares whether it contaminates food. The water company cares what comes out of the end of it. The Environment Agency cares where the waste goes instead.

These bodies do not work from a single rulebook. Water UK, the body representing the water and sewerage companies, describes the regulation of fat, oil and grease as not joined up, and says grease management in the UK relies to a large degree on the discretion of the businesses producing it.

The same guidance records more than 300,000 sewer blockages a year across the UK, up to 70% of them caused by fat, oil, grease and other material put down drains. Clearing those blockages and cleaning up the flooded properties and pollution incidents they cause costs approaching £200 million a year.

It also puts the number of UK foodservice establishments at around 360,000, and cites a study finding that only 12% used grease management equipment and around 0.15% met best practice.

This guide covers the four regimes that apply to a commercial drain, what the building regulations require, whether a grease trap is a legal requirement, what an environmental health officer looks at, and what a drainage failure costs a business in 2026.

The four rulebooks your drainage sits under

Commercial drainage has no single statute. It has four, and they attach at different moments in a building's life.

• Building regulations apply when the drainage is built, extended or altered. In England that is Part H of Schedule 1 to the Building Regulations 2010, enforced by building control.
• Food hygiene law applies every day the premises trade. It requires drainage facilities that are adequate and designed to avoid contamination, and it is enforced by the local authority's environmental health team.
• The Water Industry Act 1991 applies to what you put into the sewer. It is enforced by your water and sewerage company, which can prosecute and recover its costs.
• Environmental protection and waste law applies to the material you keep out of the drain. The local authority enforces statutory nuisance and the Environment Agency enforces waste separation.

A single defect can engage more than one at once. A cracked gully under a kitchen floor is a contamination risk under food hygiene law, a source of smells that can support an abatement notice, and a leak into the ground from a pipe you are responsible for. The same repair answers all three.

For the underlying question of which lengths of pipe are yours at all, our guide to who is responsible for a blocked drain sets out where the boundary falls.

Part H: what the building regulations require

Part H of Schedule 1 to the Building Regulations 2010 sets six requirements. Five of them bear on a commercial kitchen directly, and the sixth, H2, governs any site that is not on the public sewer.

H1 requires an adequate system of drainage to carry foul water from the appliances in the building, discharging to a public sewer where that is reasonably practicable, and to a private sewer, treatment system or cesspool where it is not. The order of priority is set in the regulation itself, which also defines foul water to include water used for food preparation, cooking or washing. That puts a commercial kitchen inside Part H without argument.

H3 covers rainwater from roofs and paved areas, and H5 requires that a surface water system provided with new building work is kept separate from the foul system where it can discharge to a separate surface water sewer. A cross-connection between the two sends kitchen waste to a watercourse.

H4 governs building over or near a public sewer. It applies to work over a drain, sewer or disposal main shown on the sewerage undertaker's map, and to work that would interfere with the use of one or obstruct access to it. An extension, a new plant room or a resurfaced yard over a mapped sewer has to be handled before the work starts.

H6 requires adequate provision for storing solid waste, and adequate access from the storage point to the collection point specified by the waste collection authority under section 47 of the Environmental Protection Act 1990. Bin store drainage sits here, and it is a common source of odour complaints against a kitchen.

Approved Document H is the 2015 edition, and the Approved Documents as a whole are under a fundamental review of building regulations guidance, with an interim report expected in Q3 2026. The requirements in Schedule 1 are set by the regulations and are unchanged by a review of the guidance.

For an existing building the route is different. Under section 59 of the Building Act 1984, a local authority can serve notice requiring the owner to make satisfactory provision for drainage, and can require the owner or the occupier to renew, repair or cleanse an existing drain.

Off the public sewer: septic tanks and treatment plants

H1 sets a priority order, and when it runs out the site falls to H2. Rural pubs, roadside cafes, hotels and holiday parks sit here.

H2 requires a septic tank, other wastewater treatment system or cesspool to be sited and constructed so that it is not prejudicial to health, will not contaminate a watercourse, underground water or water supply, and has adequate means of access for emptying and maintenance. The tank must be of adequate capacity, impermeable to liquids and adequately ventilated, and a durable notice has to be fixed in the building setting out the maintenance needed to avoid risks to health.

That covers building it. Running it falls to the Environment Agency's general binding rules, and a commercial operator stays inside them on two conditions.

• Volume. A discharge to ground must be 2 cubic metres or less a day, and a discharge to surface water 5 cubic metres or less.
• Character. The rules only apply to domestic sewage, meaning sewage from a toilet, bathroom, shower or kitchen of a house, flat or business. A discharge that is not domestic sewage needs an environmental permit.

Four more of the binding rules catch commercial sites regularly: maintenance has to be done by someone competent, sludge has to be disposed of by an authorised person, no discharge may sit within 30 metres of a public foul sewer, and on a sale the outgoing operator must give the incoming one written notice describing the system and what it needs.

Is a grease trap a legal requirement?

In England, paragraph 2.21 of Approved Document H states that drainage serving kitchens in commercial hot food premises should be fitted with a grease separator complying with BS EN 1825-1:2004 and designed in accordance with BS EN 1825-2:2002, or other effective means of grease removal. The document itself states that there is no obligation to adopt any particular solution in an Approved Document if you prefer to meet the requirement in some other way.

In Scotland it is a mandatory standard. Standard 3.7(a) of the Building (Scotland) Regulations 2004 requires every wastewater drainage system serving a building to provide facilities for the separation and removal of oil, fat, grease and volatile substances. The standard expressly does not apply to a dwelling, so it is aimed at commercial premises.

Scotland also has a dedicated offence. Section 46A of the Sewerage (Scotland) Act 1968 makes it a crime to pass fat, oil or grease from trade premises into a public sewer or a connecting drain where it interferes with the free flow of the sewer's contents. The penalty is up to 12 months' imprisonment or a £40,000 fine on summary conviction, and two years on indictment.

England and Wales have no equivalent named offence for grease. They rely on the general prohibition in section 111 of the Water Industry Act 1991, which is covered below.

Two practical points apply everywhere. The service record is the evidence that the equipment works, so it carries as much weight in an inspection as the unit itself. And a neglected internal grease trap becomes a contamination and odour source of its own, which moves the problem out of the water company's jurisdiction and into the environmental health officer's.

What an environmental health officer checks

Food hygiene law devotes three lines to drainage, and they are specific.

Annex II, Chapter I, paragraph 8 of Regulation 852/2004, which remains part of UK law, requires drainage facilities to be adequate for the purpose intended and designed and constructed to avoid the risk of contamination. Where drainage channels are fully or partially open, they must be designed so that waste does not flow from a contaminated area towards or into a clean area.

Paragraph 3 of the same chapter requires an adequate number of flush lavatories connected to an effective drainage system, and paragraph 1 requires the premises to be kept clean and maintained in good repair and condition.

They convert into a short list of things that get looked at:

• Floor gullies and open channels: Whether waste can travel from a dirty area toward a preparation area, and whether traps are in place and sealed.
• Standing water and slow-running fixtures: Evidence that the run below is restricted.
• Smells at the fixture: A dry or damaged trap letting sewer air back into the room.
• Grease management: The unit, its size against the kitchen, and the servicing record.
• Pest evidence: A defective drain gives rodents a route in, and the finding goes straight into the pest control element.
• The bin store and its drainage: An H6 issue that arrives as a hygiene finding.

Guidance on the rating scheme describes the physical condition element as covering cleanliness, layout, lighting, ventilation, pest control and other facilities. Drainage is not named in that list. It reaches the score through the items that are: cleanliness, pest control and facilities.

How a drainage fault moves your hygiene rating

The Food Law Code of Practice (England), issued on 23 October 2025, is the rulebook councils inspect against. It is written by the Food Standards Agency and issued by the Secretary of State, and it scores the structure of an establishment from 0 for a high standard of compliance up to 25 for almost total non-compliance. Cleanliness, layout, condition of structure, lighting, ventilation and facilities all feed that one number.

The Code then adds a rule that catches drainage in particular. Where a failure to comply involves both the structure and the procedures, the non-compliance is reflected in the scores awarded for both the hygiene factor and the structural factor. A blocked gully that also changes how staff handle waste is counted twice.

The score sets how often an officer comes back. Category A premises scoring 92 or higher are inspected at least every 6 months, category B at least every 12 months, and the interval stretches to 36 months for category E.

Display rules differ across the UK. In Wales and Northern Ireland a business is legally required to display its rating at or near each customer entrance, while in England display is optional. The rating is published online either way, and a business that has done the work can request a re-rating visit.

What the water company can do about oil and grease in the sewer

Section 111 of the Water Industry Act 1991 makes it an offence to discharge into a public sewer, or a drain connecting to one, any matter likely to injure the sewer, interfere with the free flow of its contents, or prejudicially affect the treatment and disposal of those contents. Water UK records that England and Wales rely on fat, oil and grease being treated as matter falling inside that wording.

The penalty on summary conviction is a fine up to the statutory maximum, and a further fine of up to £50 for each day the offence continues after conviction. On indictment it is up to two years' imprisonment, a fine, or both.

Prosecution is not the first step. Water UK's guidance records that water companies can recover the cost of removing a blockage from the business responsible and charge for damage caused to the public sewer, and that several companies have successfully prosecuted foodservice operators.

A second regime applies to the discharge itself. Trade effluent is defined in section 141 as any liquid wholly or partly produced in the course of a trade or industry carried on at trade premises, excluding domestic sewage. Discharging it into a public sewer requires the sewerage undertaker's consent under section 118, and discharging without that consent is an offence by the occupier.

Holding a consent also protects you. Section 118(3) disapplies section 111, so far as it covers matter likely to injure the sewer or interfere with the free flow of its contents, for trade effluent lawfully discharged under a consent. Scotland's grease offence carries the same carve-out for discharges consented under the 1968 Act. Whether your premises need consent is a question for your water and sewerage company, and worth asking before a blockage raises it for you.

The waste rules that now sit alongside the drain

Waste separation rules changed what a commercial kitchen can do with the material that used to end up in a drain.

Under Simpler Recycling, in effect from 31 March 2025, all workplaces in England must separate dry recyclable materials, food waste and residual waste before collection. Micro-firms with fewer than 10 full-time equivalent employees have until 31 March 2027. Food waste has to be collected even where the workplace has no kitchen.

The same guidance is direct about the drain: you must never put cooking oil down the drain. Cooking fats, oils and greases go into the food waste collection in small amounts, or through a used cooking oil collection.

Enforcement sits with the Environment Agency, which can issue a compliance notice to the waste producer, the landlord or the facilities management company, and failing to comply is an offence.

Separately, drainage odour can be a statutory nuisance. Section 79 of the Environmental Protection Act 1990 covers both premises in such a state as to be prejudicial to health or a nuisance, and smell or other effluvia arising on industrial, trade or business premises. Where a council is satisfied that one exists, section 80 requires it to serve an abatement notice.

Contravening that notice on industrial, trade or business premises is an offence punishable by a fine. A business has a defence if it can prove the best practicable means were used to prevent or counteract the nuisance.

What it costs to get it wrong

The penalties come from four different places, and they stack.

• Sewer discharge: up to two years' imprisonment, a fine, or both on indictment under section 111, and on summary conviction a fine plus up to £50 for every day the offence continues after conviction.
• Fat, oil and grease in Scotland: up to £40,000 and 12 months on summary conviction, or two years on indictment.
• Food hygiene: a fine up to the statutory maximum on summary conviction, and up to two years' imprisonment, a fine, or both on indictment, under regulation 19 of the Food Safety and Hygiene (England) Regulations 2013.
• Closure: the same regulations give a local authority hygiene improvement notices, prohibition orders and emergency prohibition notices. An emergency prohibition notice stops the business trading immediately, before a court has ruled.
• Nuisance: a fine for contravening an abatement notice on business premises.
• Cost recovery: the water company's bill for clearing the blockage and repairing the sewer, which it can pursue separately from any prosecution.

A kitchen shut by an emergency prohibition notice will only reopen when the enforcement authority issues a certificate that it is satisfied the risk has gone.

The drainage record that stands up to an inspection

Four documents do most of the work when someone asks you to prove the drainage is sound.

• A current drainage plan. A CCTV survey that produces a pipework diagram, a defect list referenced by run and distance, and the pipe material and change points. It also shows which pipes are yours.
• A grease management service log. Dates, the contractor, the volume removed, and the waste transfer notes for where it went.
• A planned maintenance schedule with evidence it ran. Jetting and inspection intervals matched to the site's output, with completion records against each one.
• A defect and response log. What was reported, when, what was done, and when it was finished.

Multi-site operators carry an extra problem, because the standard has to hold at the weakest site. A hygiene rating is awarded per premises and an emergency prohibition notice closes one kitchen, so the site with no service record sets the exposure for the group.

How Drainage.co.uk keeps commercial sites compliant

We work with commercial operators, facilities managers and multi-site brands across the UK, with dispatch hubs in more than ten cities and ISO 9001 and SafeContractor accreditation behind the work.

For a commercial site that means three things. CCTV surveys that produce the pipework diagram, defect list and distance references a compliance file needs. Jetting, drain repair and trenchless CIPP relining that fixes a failing run without closing a kitchen or excavating a trading floor. And planned preventative maintenance across a portfolio, so every site has a dated record before an officer, an insurer or a water company asks for one.

Frequently asked questions

Is a grease trap a legal requirement in a UK commercial kitchen?

In Scotland, yes in effect. Standard 3.7(a) of the Building (Scotland) Regulations 2004 requires every wastewater drainage system serving a non-domestic building to have facilities for separating and removing oil, fat and grease. In England, the building regulations guidance says a commercial hot food kitchen should have a grease separator to BS EN 1825-1 or other effective means of grease removal, so an alternative is allowed where it works as well.

What happens if fat from my kitchen blocks the public sewer?

The water company can recover the cost of clearing the blockage and repairing the sewer from the business responsible, and can prosecute. The offence under section 111 of the Water Industry Act 1991 carries up to two years' imprisonment on indictment, and on summary conviction a fine plus up to £50 for each day it continues after conviction.

Can an environmental health officer close my business over a drainage problem?

Yes. An authorised officer can serve a hygiene emergency prohibition notice where the health risk condition is met and the risk of injury is imminent. One of the three limbs of that condition is the state or condition of the premises, which is where a drainage defect sits. The notice takes effect immediately, before a court has ruled.

How much does a drainage fault affect a food hygiene rating?

More than one score. The Food Law Code of Practice scores the structure of the establishment from 0 to 25, and requires that non-compliance involving both structure and procedures is reflected in the hygiene score as well. A poor score also shortens the gap to the next inspection, which is at least every 6 months for the highest-risk category.

Do I need a trade effluent consent for a restaurant?

It depends what you discharge, and the water and sewerage company decides. Section 118 of the Water Industry Act 1991 requires the undertaker's consent before trade effluent goes into a public sewer, and discharging without the consent you need is an offence. A consented discharge is outside the section 111 prohibition so far as that section covers matter likely to injure the sewer or interfere with the free flow of its contents, so holding one changes your position.

Can I put food waste down the drain instead of paying for a collection?

No. Workplace recycling rules in England have required separate food waste collection since 31 March 2025, and the guidance states that you must never put cooking oil down the drain. Micro-firms with fewer than 10 full-time equivalent employees have until 31 March 2027.

Does my pub or restaurant need a permit for its septic tank?

Only if it falls outside the general binding rules. Those rules cover a discharge of 2 cubic metres or less a day to ground, or 5 cubic metres or less to surface water, and they only apply to domestic sewage, which includes the kitchen of a business. Above those volumes, or where the discharge is not domestic sewage, you need an environmental permit.

Who is responsible for the drains on a leased commercial unit?

The lease decides it between landlord and tenant, and it does not decide who an enforcing authority can serve. Section 59 of the Building Act 1984 requires a local authority to serve notice on the owner to make satisfactory provision for drainage, while a notice to renew, repair or cleanse existing pipework can go to the owner or the occupier. Our guide to landlord drainage responsibilities covers the residential position in full.

Does commercial insurance cover a drain collapse under a kitchen floor?

Often, and the cause decides it. Policies commonly cover sudden damage to underground pipes you are responsible for, while gradual damage and wear and tear are the exclusions insurers reach for most. Our guide to drain damage and insurance sets out what a policy pays for and the evidence an insurer needs to accept a claim.