Frequently Asked Questions


Who are Aqua Mundus?

To find our more visit our ‘About Us’ page or phone 01386 832205 to discuss further.


About Fats, Oils & Grease also referred to as FOG

Facts about FOG

Fat, oil and grease enters the drainage systems of commercial premises from washing of pots, pans, plates and utensils. In warm water FOG is in suspension and can be easily washed into the drain-line, however once the effluent cools the FOG comes out of suspension and forms a sticky coating on the walls of the pipe-work.
Left untreated this fatty-coating will build-up and in so doing will reduce the throughput of the pipe. Once the bore has been significantly reduced it is a matter of time before the there is a complete and catastrophic blockage.

The need for Fat, Oil and Grease Management
With up to 70% of drain blockages in commercial kitchens caused by a build-up of Fat, Oil and Grease (FOG) the need for effective grease management is vital for any commercial catering operation.

Do I need a grease trap or grease treatment system?
If you produce food and as a result wash-up pots, pans and utensils onsite you will be producing FOG. Even a B&B producing 10 meals per day will be generating significant build-up of fat, oil and grease in the drainage system which will in time lead to bad odours and ultimately a blockage.
But we don't cook Fatty-Food?'
A common misconception is that fat, oil and grease is only a problem for kitchens where food is grilled or friend. On the contrary - fat and oil in kitchen drainage is derived from oils, meat, fish and dairy preparation and increasingly the use of combination steaming ovens.


What’s the legislation for fat, oil and grease management?

For existing premises the reasons for fitting a FOG management system tend to be as a result of drain problems, pressure from the local authority, landlord or environmental health. It is however a requirement under the Water Industry Act 1991 to ensure that your premises does not discharge any product into the drain which may interfere with its operation.

Taken from the Water Industry Act 1991
Provisions protecting sewerage system
111 Restrictions on use of public sewers
(1) Subject to the provisions of Chapter III of this Part, no person shall throw, empty or turn, or suffer or permit to be thrown or emptied or to pass, into any public sewer, or into any drain or sewer communicating with a public sewer-
(a) any matter likely to injure the sewer or drain, to interfere with the free flow of its contents or to affect prejudicially the treatment and disposal of its contents
Thames Water reported that in 2007/2008 over 60,500 sewer blockages reported were caused in part by FOG.

With the cost running into Millions of Pounds Water Authorities are more and more adopting a 'polluter pays' principle where they will trace the problem back to the offender. The Thames Water website states "During 2007/08, we saw the continued success of the fat, oil and grease pollution prevention programme of targeting blockage hotspots, with a further 1,501 visits undertaken at food service establishments across our catchment."

For new-builds fitting a grease trap or grease removal system is a statutory requirement in the UK under Part H of the British building Regulations. Part H states under item 2.21 -
"Drainage serving kitchens in commercial hot food premises should be fitted with a grease separator complying with prEN 1825-1and designed in accordance with prEN 1825-2 or other effective means of grease removal."

PrEN 1825-1 (now BSEN 1825) is the European standard for gravity grease interceptors. The

standard provides guidance purely for separators sizes where FOG is to be removed by gravity alone. Gravity separators are very large and not often practical for retro-fit. The British Building Regulations therefore takes a practical view and allows the use of "other effective means of grease removal" which can refer to biological dosing equipment or automatic grease separators.


Water UK - Best Management practice:

"Grease traps/grease interceptors Grease traps are specially designed units which are placed in drain pipes to separate the fat, oil and grease from the rest of the wastewater. The wastewater then continues to flow to the sewage works for treatment while the grease is retained in the trap to be collected by a licensed waste oil collector at regular intervals. These units can be highly effective if they are correctly installed, serviced and maintained.

A written record of maintenance must be kept. Your local environmental health officer may be able to assist on the location and size of the unit to suit your premises to ensure it is efficient at preventing the grease causing problems in the drains."


Downloads – Water UK

Building Regulations – Part H 2.21


About Grease Management Systems

What are Grease Traps and Grease Interceptors?
Grease traps have been used since the Victorian days. They are used to reduce the amount of fats, oils and greases (FOG’s) that enter the main sewers. Effectively they are boxes within the drain run that flows between the sinks in a kitchen to the foul sewer system. They only have waste water flowing through them and are not served by any other drainage system such as toilets. They can be made from a number of different materials; e.g. Stainless Steel, Plastics, Concrete & Cast Iron. They range from 5 litre capacity to 30,000 litres and above capacity. They can be located above ground, below ground, inside the kitchen or outside the building.

What happens to the grease?
The trapped grease is stored in the trap until it is cleaned out.

Do I need a Grease Trap?
Most Local Authorities require a system to prevent grease and fat from flowing into the main sewerage system. Even if it is not required, you may want a Grease Trap to help prevent clogged drains from stopping work.

How does a Grease Trap or Grease interceptor work?
By slowing down the flow of hot greasy water and allowing the grease to cool. As it cools, the fat, oil and grease separate and float to the top of the Grease Trap. The clean water continues to flow down the waste pipe.

What happens if I don't have a Grease Trap or Grease Interceptor?
Drains block and waste water backs up. Even partial drain blockages can cause floor drains to back-up, causing pollution. Also, this stops work and may require expensive maintenance.


What else can I do to prevent blocked drains?
Fat, oils and grease cling to other solids in your waste water. Minimising the solids and food particles going down the drain will decrease the risk of blockage.

How do I choose the right Grease Trap for my application?

The size you need is determined by the amount of water going down your drain. If you have a choice, it is usually best to choose the largest size, giving the most efficient operation and longest cleaning cycle. If you would like help choosing, just let us know and we will be glad to help with your selection.

Can anyone fit it - or do I need a specialist?
We recommend that it is fitted by a qualified plumber or building contractor and should have no problems if your current pipe work is of adequate size, in good condition and is accessible.

How long does it take to get one?
For most of
Great Britain, delivery is 1-2 working days, For some of Scotland and the Islands, delivery may take longer. If your order is urgent, let us know and we will do our utmost to satisfy your requirements.
Still got a question?  Please phone us on 01386 832205 and we will be happy to assist further.