Trade Effluent is any liquid that is discharged to the public sewer from a business, trade or industrial process. This does not include domestic sewage (e.g. wastewater from toilets, hand washing, kitchens) or uncontaminated rainwater.

Trade effluent is discharged from a variety of business premises, such as:

• laundries
• vehicle washes 
• food and drink production
• metal finishing
• chemical manufacturing
• engineering

Effluent from hotels, pubs, restaurants and takeaways is not currently classed as trade effluent, though it is regulated under the Water Industry Act 1991. 

If you plan to discharge trade effluent into a public sewer, you are required by law to obtain a trade effluent consent from the Sewerage Undertaker (Wessex Water).

It is your responsibility to obtain a trade effluent consent, prior to commencing a discharge to the public sewer network.

Trade effluent must not be discharged to a surface water drain, which would discharge directly to the environment without treatment, causing pollution.

Short-term discharges such as contaminated groundwater from land remediation and building projects, are subject to temporary trade effluent authorisation.

Short-term discharges derived from flushing of heating/cooling systems, potable water mains and sprinkler systems, may not require application for a trade effluent consent. This is subject to the acceptance of specific conditions set out in our Regulatory Position Statement.

If you are unsure whether you need consent, please email trade.effluent@wessexwater.co.uk

In order to obtain permission to discharge, you should contact your Retailer who will help you complete a G/02 Form. This will be submitted to Wessex Water by your retailer and, if fully completed, will initiate the consent application process. 

If you do not know who your retailer is, check on your recent water bills or visit the Open Water website for further information.

 If you need to make a connection into our sewerage network, you will need to do this before you apply for a consent. Please follow the guidance provided by our Developer Services Team.

 As part of the consent application process, we will assess the risk associated with your proposed discharge and conduct internal consultations to determine whether we have available capacity to receive it, both in terms of Network requirements (i.e. sewer pipes and pumping stations) and Treatment requirements (i.e. receiving Water Recycling Centre).

 The Trade Effluent Officer responsible for your area may get in touch to arrange a site visit or simply to discuss the details of your application and any further information that may help us assess your proposed discharge. 

 If the proposed discharge is suitable for discharge to public sewer, capacity is available, and we do not need to refer to a third-party agency, we will issue a Trade Effluent Consent within 2 months of receiving a fully completed application. 

 Please find further guidance in the documents and links section.

Your Trade Effluent Consent is a legal document and will include the following requirements:

• Quality requirements - concentration limits (mg/l) and/or load limits (kg/day) for specific substances and parameters, relevant to your site and industry. Other substances may not be included in your consent, but you will still need to comply with our standard limits and the Water Industry Act 1991. Here is a list of indicative standard limits.
• Quantity limits - maximum daily volume (m³/day) and instantaneous flow rate (l/s).
• Monitoring requirements - effluent sampling and continuous monitoring of quality/quantity parameters such as discharge volume, flow rate, pH and temperature. We will expect monitoring equipment to be regularly calibrated and maintained.

Once the consent is issued, compliance with these requirements will be audited via routine sampling and monitoring. Analysis reports will be sent to you automatically via email.

Non-compliance with the consent requirements will be communicated to you with a formal letter, asking you to investigate the issue and get back to us with the following:

• Reason for the non-compliance
• Steps taken to resolve the non-compliance
• Proposed steps and timescales to prevent reoccurrence

This is the first step of our Enforcement Policy. Legal action will be taken against persistent non-compliance and discharges with an adverse impact on public health and safety, the integrity of our assets or the environment.

Wessex Water reserves the right to recover any cost incurred following a breach.

Here is our Enforcement Policy.

Standard trade effluent charges are billed through your retailer. Please contact your retailer for any information about trade effluent charges or queries about your trade effluent bills.

Trade effluent charges are calculated based on information provided by both the Wholesales (Wessex Water) and the Retailer, using a formula known as Mogden Formula. This takes into account the below parameters, to determine the cost of transporting, treating and disposing of your discharge and relative by-products:

• Volume
• Chemical Oxygen Demand   
• Suspended Solids

Generally, meter readings combined with routine sampling of your effluent, are used to obtain a statistically validated average of the above parameters.

If you would like to know more about wholesale charges, they are available here: wholesale charges.

Non-standard trade effluent charges, such as cost recovery following consent breaches, are charged directly by Wessex Water.

Wessex Water keeps a register of all trade effluent consents within the region, which is available for the public on request.

Please contact our Trade Effluent Team at trade.effluent@wessexwater.co.uk if you would like to receive a copy of a consent held in the public register.

• Indicative Limits for Common Substances
• Trade Effluent Enforcement Policy
• Application Form for Temporary Agreements
• Trade Effluent Permanent Application Screening document
• Trade Effluent Temporary Application Screening document
• Guidance for non compliance meeting and action plan
• Developer Services team and guidance
• Open Water website
• EA special category effluent
• Flushing of systems position statement
• Wholesale charges scheme for 2022-2023