Trade effluent

If you plan to discharge trade effluent into one of our public sewers, you are required by law to obtain a trade effluent consent from us.

It is your responsibility to obtain a trade effluent consent prior to discharging into the public sewer network.

Trade effluent must not be discharged into a surface water drain, which would discharge directly into 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 heating/cooling systems, potable water mains and sprinkler systems may not require an application for 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.

You will need to apply for trade effluent consent through your retailer. They will assist you in completing a Trade Effluent Application form. If you are unsure who your retailer is, please check your most recent water bill.

They will submit the form to us and, if fully completed, will initiate the consent application process.

If you are not connected to our sewerage network, you will need to apply for a sewer connection before we can give you consent.

After you have submitted your application, we will assess the risk associated with your proposed discharge and conduct internal consultations to determine whether we have the available capacity to receive it, both in terms of network and treatment requirements.

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

If the proposed discharge is suitable for discharge into a 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 two months of receiving a fully completed application.

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.

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.
• Quality 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. For more details, please read our policy and guidance on monitoring the flow rate and volume of a trade effluent discharge.

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
• the steps taken to resolve the non-compliance
• proposed steps and timescales to prevent recurrence.

Our trade effluent enforcement policy sets out the principles we will follow when considering enforcement against customers who are in breach of their trade effluent consents.

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.

We reserve the right to recover any cost incurred following a breach.

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 wholesaler (Wessex Water) and the retailer, using a formula known as the ‘Mogden Formula’. This takes into account the parameters below 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 the routine sampling of your effluent, are used to obtain a statistically validated average of the above parameters. Find out more about our wholesale charges.

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

We keep a register of all trade effluent consents within the region, which are available to the public on request. 

Please email us at trade.effluent@wessexwater.co.uk if you would like to receive a copy of a consent held in the public register.