Trade effluent is anything other than domestic sewage. If you need to discharge trade effluent into one of our public sewers, you need our permission.
What is trade effluent?
Trade effluent is any liquid waste (effluent) discharged into our sewers from a business or industrial process. This can be best described as anything other than domestic sewage (toilet, bath or sink waste) or uncontaminated surface water and roof drainage (rainwater).
Do businesses need permission to discharge trade effluent?
Yes. It is a legal requirement for any business to get our permission before any discharge to our public sewers takes place, under the Water Industry Act 1991. This is because illegal discharges can have severe effects on the environment, damage our sewers, inhibit our wastewater treatment processes, and pose a significant health and safety risk to our employees.
What kinds of permission are there?
We can issue two different forms of permission:
- A trade effluent consent with prescribed maximum limits for several parameters including flow which are subject to regular monitoring by our trade effluent inspectors; or
- A letter of authorisation for those businesses who need very small discharge volumes, occasional discharge or a one-off event and when the effluent is proven be of very low risk for the sewer and receiving sewage works.
A trade effluent consent or letter of authorisation is a legal agreement between us and your business stating the permitted limits of discharge strength and volume.
My business needs to discharge trade effluent. How do I get your permission?
You can request permission by completing our trade effluent enquiry form. Before you proceed you may need to gather the following information:
- Compile any sample data information you may have with analysis for at least biological oxygen demand, chemical oxygen demand, settled chemical oxygen demand, suspended solids, ammonia (measured as NH4-N), total phosphorus (measured as PO4-P), fats oils and greases, pH and a suit of metals. Other analytes may be relevant to your business activity such as anionic detergents, sulphate, methane and cyanide.
- Drainage plans as we may need to assess and inspect your drainage plans.
- How is the flow discharge going to be monitored in terms of metering.
- Intended volume of discharge in meters cube per day and maximum instant flow.
What happens after I submit my enquiry form?
After processing your enquiry, we will send you a document called a ‘preliminary details form’ for you to complete and email (or post) to us, along with other supporting information.
Once we’ve received your preliminary details form, we will assess the acceptability of the discharge to the receiving sewer, pumping stations and wastewater treatment works.
For businesses handling very toxic chemicals such as chromium, lead, zinc, cadmium and cyanide amongst others we are required to carry out a more comprehensive environmental risk assessment so our determination may take longer.
This is all done on a case-by-case basis and we cannot guarantee that there is capacity for your business’s effluent however we may be able to offer a lower discharge volume and strength.
If the risk of accepting a discharge is acceptable, we will issue you with a formal notice or application. You must return this fully signed and dated, so that we can issue you with formal ‘Consent to Discharge’ documentation that will allow you to discharge.
What costs are involved when it comes to requesting trade effluent permission and when do I need to pay them?
There are no upfront charges and you will only be charged if a consent is granted. The fee is detailed in our scheme of charges and reviewed annually.
Frequently asked questions about trade effluent
It’s a legal agreement between us and your business stating the permitted limits of discharge strength and volume.
All applications are reviewed on a case-by-case basis. Dependant on capacity within our sewer network and receiving wastewater treatment works, we set specific limits on trade effluent consent when it comes to its volume, organic load, fats, oils and greases, suspended solids, nutrients, pH, toxic metal, sulphate, sulphide, methane, cyanide, other controlled substances and emerging contaminants of risk
It’s your responsibility as the business who wishes to discharge to obtain our permission, not our responsibility to identify where the trade effluent is coming from.
We monitor trade effluent consent compliance in two ways:
i) Strength – the average of results from regular spot sampling by our trade effluent inspectors (vs permitted limits)
ii) Volume – as recorded by a discharge flow meter, or a calculation based on recorded incoming water (vs permitted limits).
We monitor compliance with letters of authorisation in the same way, but on an ad-hoc as required basis.
It’s your responsibility to make sure you comply with the limits of your trade effluent consent or letter of authorisation; remember it is a legal agreement. If you are planning on exceeding your permitted limits, please contact us as soon as possible and we will advise where possible. If we identify that your business is exceeding permitted limits, we will contact you.
If you want to discharge any perishable product, you need to contact us before discharging it to our sewer network. Any illegal discharge can not only have severe effects on the environment, but is also an illegal (criminal) act under the Water Industry Act 1991. We will enforce our regulatory duties when it comes to monitoring our network for illegal effluent that damages the environment, and this may include prosecution for environmental offences.
We discourage our customers from using the sewer to dispose of surface water. When uncontaminated, surface water is best returned to the environment and you need to consult with the relevant environmental regulator in your area.
Where a trade effluent consent is issued, trade effluent bills include a fixed charge and variable charges that vary with the volume and sampled strength of discharged effluent. Trade effluent bills are sent either monthly, quarterly or six monthly in arrears, depending on the average monthly charge. This will be a dedicated bill, separate to your business’ water and domestic sewerage charges. Where a letter of authorisation is issued, trade effluent is billed in the same way as domestic sewage.
Where a trade effluent consent is issued, trade effluent bills are calculated using the water industry standard ‘Mogden’ formula. This means bills are directly related to the sampled strength (in particular ‘COD – chemical oxygen demand’ and ‘SS – suspended solids’) and volume of trade effluent discharges.
Where a letter of authorisation is issued, trade effluent is billed in the same way as domestic sewage.
You can find more information within our scheme of charges.
Where a trade effluent consent is issued, the sampled strength and volume of trade effluent discharged are used to calculate bills, independently of whether the strength and/or volume is deemed compliant with your business’ trade effluent consent, i.e. reducing the volume/COD/SS of your business’ trade effluent will continue to reduce bills when already within consented limits. Where a letter of authorisation is issued, trade effluent is billed in the same way as domestic sewage, independently of whether the strength and/or volume is deemed compliant with your business’ letter of authorisation.
No, the completion of the trade effluent enquiry form is not deemed a formal notice under the Water Industry Act 1991. The information provided on the enquiry form will just enable us to progress with the next stage of the application process.
A trade effluent consent or letter of authorisation is not transferable between premises or businesses. You will need to apply for a separate or new consent.
If you need to expand your business and the current trade consent or letter of authorisation is not fit for purpose, you will need to request a review because we need to assess if there is enough capacity in our sewer network and receiving sewage works to cater for the potential increase in flow and/or load. Please contact us before you actually expand.
Still need more information?
If you still have unanswered questions, email our trade effluent team on Trade.Effluent@dwrcymru.com