Trade Effluent Consent Explained: Who Needs One and What It Costs
If your business puts anything down the drain other than ordinary domestic waste water, you may need a trade effluent consent — and you may already be paying for one on assumptions that no longer reflect what you actually do.
Trade effluent is any liquid waste discharged from a business process into the public sewer. Discharging it without consent from your regional wholesaler is an offence, and the charges are calculated from the volume and the strength of the discharge, both of which are worth reviewing because they are often based on out-of-date assumptions.
This guide covers what counts as trade effluent, who needs a consent, how the charges work and where businesses most often overpay.
What counts as trade effluent?
Trade effluent is liquid waste produced by a business activity, as distinct from the water from toilets, sinks and staff washrooms, which is ordinary domestic sewage. The distinction is about the process, not the industry, so plenty of businesses that would never describe themselves as industrial produce it.
Common examples include:
- Wash-down water from food production, butchery or fish preparation
- Cooling water and boiler blowdown
- Vehicle and plant washing, including forecourts and commercial car washes
- Laundry and dry cleaning discharges
- Water from printing, plating, chemical dosing or laboratory work
- Discharges from breweries, distilleries and soft drink production
If you are not sure which category your discharge falls into, the wholesaler decides, and it is far better to ask than to assume.
Who needs a trade effluent consent?
Any business discharging trade effluent into the public sewer needs written consent from the regional wholesaler before it starts. Consent is site-specific and discharge-specific: it sets out what you may discharge, in what volume, at what rate and within what limits for strength and content.
Discharging without consent, or outside the terms of the consent you hold, is a criminal offence and can lead to prosecution as well as the cost of any damage caused to the sewer network or treatment works. It is not a technicality that gets overlooked quietly.
You will also need to apply for a variation if your process changes materially — a new production line, a change of chemicals, a significant increase in volume, or a change of use for part of the site.
How are trade effluent charges calculated?
Trade effluent is charged differently from ordinary wastewater, because treating it costs more and the cost depends on what is in it. Charges are typically built from:
| Element | What it reflects |
|---|---|
| Volume | How much effluent you discharge, often derived from your metered water use less an allowance for domestic use and losses |
| Strength | The organic load and suspended solids in the discharge, which drive the cost of treating it |
| Treatment stages | Which parts of the treatment process your effluent actually requires |
| Reception and conveyance | Getting the effluent through the network to the treatment works |
The important point is that volume and strength are frequently estimated rather than measured. If the assumptions were set years ago, they may bear little relation to your current operation.
Where businesses most often overpay
The recurring themes we see are:
- Volume assumptions that ignore water lost to product or evaporation. If water goes into what you sell, or leaves as steam, it never reaches the sewer and should not be charged as effluent.
- Strength figures set at a worst case. Where sampling has not been done recently, an assumed strength may be far above what a current sample would show.
- Consents that outlived the process. A line that closed, a chemical that was substituted or a shift pattern that changed can all reduce the true discharge without anyone updating the consent.
- Domestic allowances that are too low. The deduction for toilets and washrooms should reflect actual headcount.
- Duplication with surface water charges. It is worth checking that the same water is not being charged twice under different headings, and our guide to surface water drainage rebates explains how that charge is set.
Because these charges recur every year, correcting an assumption once can be worth a great deal over the life of a site. Trade effluent is one of the specific things we look at in a business water review.
What to do if you think your charges are wrong
Start by getting a copy of your current consent and reading it against what your site actually does today. Then compare the volume being charged with your metered water intake, and account for anything that leaves the site other than down the drain. If the numbers do not reconcile, ask the wholesaler how the figures were derived and what sampling they are based on.
Where strength is the issue, an independent sample can be persuasive. Where volume is the issue, sub-metering the process water is often the cleanest way to prove the point.
Frequently asked questions about trade effluent
What is trade effluent?
Trade effluent is liquid waste produced by a business process and discharged into the public sewer. Water from toilets, sinks and staff washrooms is ordinary domestic sewage and is not trade effluent.
Do I need consent to discharge trade effluent?
Yes. You need written consent from your regional wholesaler before you begin discharging, and discharging without it or outside its terms is a criminal offence. You also need a variation if your process changes materially.
How are trade effluent charges worked out?
They are based on the volume discharged and the strength of the effluent, together with the treatment stages it requires and the cost of conveying it. Both volume and strength are often estimated rather than measured, which is why they are worth reviewing.
Can trade effluent charges be reduced?
Often yes. The most common reductions come from correcting volume assumptions where water leaves as product or vapour, updating strength figures with current sampling, and revising consents that no longer match the process on site.
Get your discharge charges reviewed
Send us a recent water bill and a copy of your consent and we will tell you whether the volume and strength assumptions still stack up. See our business water service, our guide to what business water costs, or the full list of services we offer. You can also call 0151 541 6767.