Calculating Trade Effluent Charges Using the Mogden Formula
In this expert guide the Mogden Formula, used by UK water companies to calculate trade effluent charges comes under review from the industrial wastewater specialists at Water Treatment Services. The guide looks at its history and how it is used to calculate the costs for discharging effluent. It also considers how the formula can be used to identify opportunities for environmental improvement and cost reduction for businesses.
What is the Mogden Formula?
The Mogden Formula is a complex mathematical formula incorporating several important variables. It is used by UK water companies to calculate the trade effluent charges a business will incur when it disposes of its industrial effluent to a foul sewer.
The name of the formula comes from the Mogden Water Works in Isleworth, London. They were the first to develop the formula, and it has since been adopted as the industry standard across the UK water networks.
When it was initially introduced, the Mogden Formula was intended to cover a water company’s costs when collecting trade effluent, transporting it to the sewage works and then treating it to make it safe enough to discharge into a local water course.
Your local water company will use the Mogden Formula to calculate how much they will charge you to collect and dispose of any trade effluent which your business produces. The calculation will produce a cost per cubic metre, and takes into account a range of variables including the levels of contamination and strength of the effluent. The cost per cubic metre is then simply multiplied by the total volume of trade effluent produced to give your total invoice amount.
The Mogden Formula
The Mogden Formula is expressed as:
Trade Effluent Charge = R + [(V + Bv) or M] + B(Ot/Os) + S(St/Ss)7
Yes it’s fairly complicated, but the good news is that there’s plenty of support available from our team of industrial wastewater specialists which will help you make sense of it all.
What do each of the variables used in the formula represent:
| Variable | Description |
|---|---|
| R | This is the charge for receiving the effluent, given per cubic metre. |
| V | The charge for primary treatment, per cubic metre. |
| Bv | An additional charge if the wastewater needs to be treated biologically. This doesn’t apply in every case. |
| M | Extra charges per cubic metre if the water is discharged into the ocean. |
| B | Charge depending on the biological oxidation of sewage. |
| Ot/Os | Chemical oxygen demand measurements. |
| S | Charge for getting rid of primary sewage sludge, in kg. |
| St/Ss | Measurement of total suspended solids in the effluent, measured per litre. |
So what does the Mogden Formula tell us?
In essence, the formula tells us that the dirtier the wastewater or effluent a business is producing, and the greater the volume of solids suspended in it, the higher the trade effluent charges (per cubic metre) will be. If you can clean up or reduce the amount of effluent before it leaves your business, you’ll see the charges imposed on you decrease.
There is some variation between regional water companies and how they apply the formula. Many add a separate ammonia variable into the formula. If you’re not sure how your local water company is using the Mogden Formula then check online as they are legally required to make this information public. OFWAT, the water services industry regulatory body in England and Wales, are responsible for controlling the overall level of charges.
Reducing your trade effluent charges
There are lots of easy ways in which companies can control and reduce the amount of water they are using which in turn will have an impact on the volumes of wastewater they produce. Most of this falls under the umbrella of good maintenance and resource efficiency and includes simple things such as fixing water leaks quickly, reminding staff to turn off taps, or only using hosepipes when strictly necessary. However, one of the consequences of these water saving measures might be an increase in the overall strength of the effluent they create, which could hike bills up.
Taking a look at how the Mogden Formula calculates costs you will also see that there are three key elements that businesses can control to help improve their own environmental performance and to reduce trade effluent charges including:
If a business is able to lower the amount of water it uses, the levels of contamination, and total volumes, their trade effluent charges can be reduced. Businesses could also consider introducing additional wastewater treatment processes to improve the quality of their effluent before it enters the public sewer systems.
If you are looking to reduce your trade effluent charges you should seek expert advice from the specialists at Water Treatment Services about both practical and innovative ways to reduce your water bills and produce effluent which is as clean as possible.
Specialist industrial wastewater and trade effluent solutions
Water Treatment Services offer a comprehensive range of trade effluent and wastewater management solutions. Find out how we can help reduce your costs, achieve regulatory compliance and improve environmental performance. Our experts can provide advice and full support to help you identify the most appropriate strategies for managing your industrial wastewater and effluent streams.
With offices in London serving the South and South East England, Manchester (North West), Birmingham (Midlands), Bristol (South East England and Wales), Leeds (North and North East) and Glasgow (Scotland), supported by regional teams of specially trained engineers, wastewater specialists and technicians we offer cost effective environmental support solutions across the whole of the UK and Ireland.
Contact us today to learn how our expert wastewater management solutions can help you improve environmental performance, reduce costs and achieve discharge consent standards.
Further reading…
More information about our tariff audits and cost recovery solutions for industrial wastewater and trade effluent solutions … here →
