The True Cost of a Grease Trap


Grease traps are currently in use in kitchens across the country, intercepting fats, oils and grease (FOGs) before they make it out through waste water pipes and into the sewers, where they’ll form fatbergs over time.

The FOG problem is pollution pure and simple: fatbergs make sewer overflows more likely and so make it more likely that raw sewage will end up being sent straight in our waterways. A high quality grease trap, maintained in good working order, can be relied upon to help stop such overflows from happening – cutting down on the environmental costs of our national love of fried fast food.

What’s more, a good trap can be relied upon to protect you from financial penalties: as each berg costs water companies £100,000 to remove and, increasingly, those costs are being passed onto food businesses deemed to be at fault.

All in all, grease traps are great. But many people are still asking: are they really worth it?

For those who are new to the FOG issue, the price tag seems huge.

So, let’s break it down. Starting with:

The Big Buy

Stainless steel grease trap

The price tag on a new grease trap set-up will vary immensely, depending on the size of the GT, the number you’ll need, the quality and the type: whether manual or automatic. You might be spending anywhere from just over a hundred pounds for a very small and flimsy manual trap to thousands for an automatic trap in a size more suited to a full restaurant.

Want to know how to work out how much a grease trap will set you back? Here’s a quick guide:



  • Size

To work out the size you’ll need, you need to work out your waste water output. If your pipes are properly installed, you’ll be able to find this out with ease: by checking your waste water pipe diameter. Decide what size grease trap you need and get a trap which can handle your flow.

  • How many traps do you need?

If you’ve got multiple waste water pipes which don’t come together within your kitchen, you may need to buy a couple of traps rather than just the one. While this will double your price tag, it’ll be cheaper than reconfiguring your piping.

  • Quality

While the start-up costs may be greater, a higher quality trap will last far longer than one with flimsy components in the same conditions. Take the GreaseMaster GM50, for instance: it weighs in at £2,600 including VAT, but comes with a life expectancy of over ten years. Split that start-up price up over its life span and £260 a year for premium grease management doesn’t sound so bad.

  • Type

Manual stainless steel grease traps are cheaper than automatic traps. But while manual traps are passive – they’re just a box which slows the flow of waste water long enough for the FOG and solid matter to separate out from the water – automatic traps will actively strain the waste water to remove the solids, making it easier to collect and dispose of them. This extra expense makes clean-up quicker.

How Do I Know If I Should Get a Manual or Automatic Grease Trap?

Grease Trap Installation

Grease traps are relatively simple machines without moving parts or electrical components. This makes them relatively easy to fit meaning that businesses can install their own trap without needing to fork out on costly specialist installation services. If you're adept at a bit of DIY then installing your own grease trap shouldn't pose too many problems. Simply make sure your sink is empty and connect the grease trap inlet and outlet securely to the sink and the main waste outlet with the correct sized couplings. You should carry out a few simple checks once grease trap installation is complete both prior to switching on the taps and after. 

  • Make sure the grease trap is level
  • Make sure seals are tight and there are no leaks
  • Make sure the lid is securely sealed

If you're not confident with some piping and a tool kit then you can always enlist any local plumber to help.


To ensure your trap keeps keeping your FOG out of the sewer for as long as possible – you’ll need to treat it kindly. Cleaning spray, sponge, bowl and rubber gloves

You’ll need to clean it. Automatic traps collect FOG in a separate container that is easily accessible and convenient to clean. Passive or manual grease traps require more input. Once they are 25% full of FOG, grease traps stop working as effectively and they’ll start letting some fats, oils and grease slide on into the sewers. To keep passive traps working optimally, you’ll need to crack yours open once a month (at least), scoop out the FOG and solid waste and scrub that box until it shines.

This regular cleaning isn’t without its costs. Doing it yourself will save you money, but you’ll still have to pay for equipment, which you’ll need to pump the waste out of your trap, and for grease disposal. The cost of in-house time and labour spent cleaning also needs to be factored in.

If you have some extra money to spend – say £2,000-4,000 per year – you might want to go with the pros instead. Saving you the hassle, booking in professional cleaners on the same day each month can also help ensure that your grease trap is scrubbed out and checked over by experts like clockwork – many cleaning companies even charge surcharges if your trap is over 25% full, giving you an incentive to ensure that you look after it well.

That incentivised GT care can mean that, in the long run, disasters are averted and you save yourself a fortune in emergency repairs.

If you want to step-up your FOG game even more, you may want to add some add-ons.

Add Extras


GreasePak Biological Drain Maintenance System GreasePak Biological Drain Maintenance System


Adding well chosen extras to your grease management arsenal is a great idea but bear in mind that going the extra mile can cost a little extra, too.

Bio-dosers are all the rage right now with two types currently available – those which work on your drains and those which work on your traps. They all work in essentially the same way: by regularly releasing a dose of fat-digesting bacteria which coat the walls of your pipes or your trap. These bacteria then begin to break down the FOG around them, ensuring that your traps take longer to fill up and so ensuring that your FOG waste is even less likely to end up in the sewer.

Adding a bio-dosing set-up to your grease trap will cost you a couple of hundred pounds to start with and then around £600 a year in re-fills. Meanwhile, adding a bio-doser to your drains will cost around £500 in start-up costs and then around £400 a year for refills.


How Does the Cost of Getting a Grease Trap Compare To Going Without? Calculator with sheet of calculations and pen

Looking at the priciest options: a high-end trap will set you back around £3,000 and, with a top-of-the-range drain bio-doser at around £500 and the best professional maintenance, you’ll be looking at £3,500 total start-up costs and then £4,400 a year – a total of £7,900 for your first twelve months of first-rate grease management. Ongoing annual costs thereafter will obviously be less as you already have the equipment in situ and the only thing required is maintenance.

That sum pales in comparison to the fines we’ve seen handed out for fatbergs, ever since a Cambridgeshire Chinese restaurant was fined nearly £16,000 for poor grease management in 2006. While there have been some restaurants who have got away with less, the colossal £420,000 fine Thames Water handed out last year to a food factory suggests that fines for fatbergs will only be getting heftier in the coming years.

While the cost of a grease trap can seem sizeable, the costs of going without can be catastrophic for any small business – not to mention the environment.