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Trade effluent consent

A trade effluent consent is a legal document issued under the regulations within the Water Industry Act 1991. It is issued to the owner or occupier of a commercial or industrial property.

A Southern Water engineer smiles and tests a water sample in a water treatment works

How does the consent work?

If your premises are within our region and you’re proposing to discharge trade effluent to the public sewer, you’ll need our prior written consent. Under section 118 of the Water Industry Act 1991, it's an offence to discharge trade effluent without consent and doing so may lead to prosecution.

The consent contains several conditions that cover the quality and quantity of the discharge. 

To apply for trade effluent consent or request a change to an existing consent, you will need to contact your retailer. 

Frequently asked questions 

Here are answers to some commonly asked questions about trade effluent consent.

We will issue a trade effluent consent for discharges greater than six months duration. If you have an existing consent and want to move location within our region, you will need to apply for a new consent before the move.

A temporary consent will be valid for six months, after which the consent will automatically end. A temporary consent cannot be extended. Should a temporary discharge extend beyond six months, the retailer must submit a new temporary consent application.

Examples of temporary discharges are:

  • Land remediation
  • Ground dewatering
  • Building site discharges
  • Pipework cleaning and flushing

We may issue a temporary trade effluent consent for multiple sites, called multi-site temporary consent. To qualify for this consent, the discharges must be of very low risk to us. We'll assess this at the time of application.

The consent will contain a number of conditions including those that control the quality and quantity of the discharge. Most consents will contain numeric limits for one or more of the parameters listed below.


Expressed in cubic meters per 24-hour period, the volume is limited and assessed on an individual basis. This prevents overloading of the receiving treatment works.

Discharge flowrate

Expressed in litres per second, the discharge flowrate is limited and assessed on an individual basis to prevent sewer flooding.


The standard range of pH in our region is 6 to 10. Extremes of pH can create unsafe working environments, affect the biological treatment systems in the receiving treatment works and damage the sewer network.


We limit this to a maximum of 43°C at the point of discharge to the sewer. This is to protect the staff working in our sewers, minimise odours and reduce the risk of explosive atmospheres.


Ammonia is classified as toxic and dangerous for the environment. It is highly toxic to aquatic animals and can cause unsafe sewer atmospheres.

Ammonia is found in sewage, mostly in human urine and some household cleaning products. Some industrial effluents, especially from mining, crude oil processing, metal finishing, pharmaceutical production or food processing facilities, may also contain ammonia. This parameter may also be used for charging purposes.

Chemical oxygen demand (COD)

COD is a measurement of the oxygen required to oxidise soluble and particulate organic matter in water. When effluents with high COD levels are discharged into the environment, there will be a reaction of the dissolved oxygen available, potentially causing losses in the ecosystem. COD levels are limited to prevent overloading of the wastewater treatment processes and ensure there is no detrimental impact on the environment.

Soluble organic compounds, residual food waste, sugar, and emulsified oils are common sources of COD. This parameter may also be used for charging purposes.

Suspended solids

This is controlled to ensure there are no blockages in the sewer and reduce treatment and transportation costs. This parameter may also be used for charging purposes.

Fat, oil and grease

Also known as FOG, this is controlled to prevent blockages in our sewers. It can also cause operational difficulties at pumping stations and treatment works. Some of the most common sources include restaurants, pubs, food processing facilities, automobile service shops and pharmaceutical manufacturing processes.


Sulphate can cause corrosion of concrete sewers and the production of odours.

Sulphate is naturally present in surface water and groundwater as water moves through soil and rock formations that contain sulphate minerals. Many industrial wastewaters, particularly those associated with mining and mineral processing, can contain high concentrations of sulphate.


This includes metals such as copper, lead, nickel, zinc, chromium, cadmium, antimony, tin, silver, etc. The presence of metals can inhibit biological treatment processes and may accumulate in the environment. An Environmental Impact Assessment is required.

The most common sources of metals in trade effluent are from metal finishing and electroplating activities, mining activities or textile industries.

Since 1 April 2017, the business retail water market has been open to businesses, charities and public sector organisations with premises that qualify.

These ‘non-household’ customers are likely to be eligible if their premises are:

  • Used mainly for business
  • Supplied from a wholly or mainly English-based water company

Licensed retailers now buy wholesale water services – the physical supply of water and the removal of wastewater – from the regional water companies, who continue to supply your water, treat your wastewater and maintain the water and wastewater pipe networks.

The retailers package these water services with other services and compete for customers.

Customers are free to choose their retailer by looking at who has the best deal for them. If you don’t have a retailer yet, you can find a retailer now.

Every business premises has a unique Supply Point Identifier (SPID number) to identify the water and/or sewerage supplies at the property. You can find a copy of your water and sewerage SPID on your bills. Or, you can learn your SPID by contacting your retailer and providing your premises address.

In some cases, you may not have an existing SPID and a SPID will be specifically created for your site on issuing of a trade effluent consent.

Yes, in some circumstances. If, after our consultation assessments, the proposed trade effluent is unsuitable for discharge into the sewer, we will refuse the consent. We’ll inform you at the earliest opportunity of the exact reasons for the refusal.

Under Section 122 of the Water Industry Act 1991, you have the right to appeal when the sewerage undertaker refuses to grant consent.

Yes. It is a criminal offence under section 121 of the Water Industry Act to breach any consent condition set on your trade effluent consent. Doing so may result in enforcement action taken against your company and, in some cases, prosecution.

Enforcement actions will vary from case to case. This will be mostly determined by the frequency and severity of the breach.

The Trade Effluent inspector will engage with a Network Protection and Enforcement officer, should the breach trigger an escalation to a higher level of enforcement. Enforcement methods that may be used during this process include:

Breach letters:
A breach letter is always issued when a consent breach is detected – these can include sample breaches and/or non-sample breaches. The letter will ask you to investigate the circumstances associated with the failure and confirm what measures are being taken to prevent a reoccurrence. You'll need to provide a written explanation within 14 days of the issuing of the letter.

Action plan:
In some cases, before proceeding with further escalation, your company may receive an action plan.
The object of this is to give you the opportunity to detail the actions that you intend to take to bring your company’s discharge back to within the sample limits or non-sample conditions of the consent and to ensure that it remains within those limits in the future. This should allow us to track the progression of these actions and receive regular updates.

Formal Sampling:
This may be initiated if a requested Action Plan is not completed or does not deliver required compliance. If the sample breach is severe then formal sampling may be initiated at the same time, or instead of an action plan. Should the results show that your trade effluent discharge continues to be in breach of consent limits then formal action, which may include prosecution, will be taken.

Formal Caution:
In cases where a prosecution is not considered to be the most appropriate course of action, the issue of a formal caution will be considered. This is the written acceptance by your company that you have committed an offence. This may be used where a prosecution could properly have been brought.

Any breach of consent conditions constitutes a criminal offence and this may lead to prosecution.

No. Trade Effluent should only be discharged to a foul or combined sewer.

A surface water sewer goes directly into a watercourse. As such, it should only collect uncontaminated rainwater run-off. Discharging wastewater into a surface water sewer can cause serious environmental pollution.

No. Your trade effluent consent will remain active unless you are no longer discharging trade effluent into our sewers, or you close your premises. In that case, you will need to submit a termination request to end your consent and all the charges associated with this. You will need to contact the Southern Water Trade Effluent team or your retailer to submit this request.

We can also terminate a consent if we have enough evidence that a trade effluent discharge has ceased. We will notify your retailer at the earliest opportunity.

Yes. We have the right to enter your site at any reasonable time to take a sample of your trade effluent.

Under Section 171 of the Water Industry Act 1991, any person designated by a sewerage undertaker shall have a right to enter any premises at all reasonable hours for the purpose of taking action or carrying out any works (i.e. collection of trade effluent samples or enforcement action when Southern Water believes a discharge is harming our assets or the environment).

If your company temporarily ceases its operations or temporarily stops discharging trade effluent, you should notify your retailer. Following agreement by Southern Water and the retailer, the consent can be put on a discontinuation status. The trade effluent charges payable for the agreed duration of the discontinuation shall be trade effluent standing charges only (no volumetric charges).

Discontinuation of the trade effluent consent will apply from the first day of the following month.

You must notify us straight away and apply for the changes through your retailer. This includes variation of current consent limits, change of legal company name or any change in the legal identity of the company. A termination request will be submitted if you are no longer discharging trade effluent into our sewers.

Please contact us at trade.effluent@southernwater.co.uk if you would like to request public register details (details of consented trade effluent discharges and premises within the Southern Water catchment).

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