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You are here: Home > Services > Trade effluent


Trade effluent charges

We issue trade effluent bills to customers who are consented to discharge trade effluent.

These charges are reviewed annually to ensure they reflect the cost of the services we provide. These services include reception, conveyance and treatment of effluent.

The charge you pay is determined by: 

  • the volume of effluent you discharge
  • the level of sewage treatment applied
  • the strength of effluent you discharge.

Customers that have a strong trade effluent strength pay a higher unit charge than those with weak effluent. The table below gives an indication of the typical unit charges (2008/09) for different types of customer:

Unit charge examples 

Unit charge examples chart

The unit charge is made up from a fixed volume charge and variable strength charge, related to the average suspended solids and Settled chemical oxygen demand (COD) content. COD is a measure of the organic content of the trade effluent.

Examples of the how the unit charge is made up for different types of customer is shown below:

Breakdown of unit charges - examples

Breakdown of unit charges pie chart

Volume assessment

Water recovery system at laundryAssessment of the chargeable trade effluent volume is usually carried out in one of three ways:

1. direct measurement of flow using a customers effluent flow meter
2. use of water supply consumption figures less agreed allowances
3. process sub-metering or pumping rates.

Customers who are required to provide and maintain trade effluent flow monitoring facilities must provide calibration certificates at six monthly intervals.

Strength determination

Certain categories of effluent are classified as standard strength discharges and in these cases the settled COD and suspended solids concentrations are predetermined. The following pre-determined standard strengths may be applied (but are subject to review at Wessex Water’s discretion):

Category Settled COD (mg/l) SS @ pH 7 (mg/l)
Launderette 570 227
Vehicle wash 70 135
Small brewery 2,206 350
Photo processor 370 40

Good housekeeping at food manufacturing siteThe strength of trade effluent may also be determined from the average results of samples taken during the charging period. Individually agreed fixed strengths based on samples taken in previous charging periods may also be agreed in certain circumstances.

Reducing the volume, suspended solids or COD content of the trade effluent will reduce your trade effluent bill.

A copy of our trade effluent charges scheme is available to download. For further information please contact your commercial waste water advisor.

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