Treatment works compliance - performance commitment data
What are performance commitments (PCs)?
The water regulator Ofwat sets targets called performance commitments (PCs) to ensure companies deliver the best possible service for customers, society and the environment. Wessex Water has a range of PCs for the 2020-25 period.
Each year we report our results against these commitments, in our Annual Performance Report.
Where appropriate we’re publishing the data underpinning calculation of the PCs – you can find our other PC datasets in the Performance Commitments section.
Treatment works compliance PC
Every day we treat 472 million litres of sewage to make it safe to release back into the environment. For each of our water recycling centres (WRCs), the Environment Agency (EA) sets standards for the treated wastewater we discharge back into the environment. The standards are set out in a ‘permit’ for each site, which gives thresholds for various parameters (e.g. ammonia, chlorine).
Our water treatment centres (WTCs), which clean water ready to go to customers, also have permits specifying standards for any water we discharge back to the environment.
On occasions the permit standards for the water returned to the environment from WRCs and WTCs are not met. This could be for a variety of reasons such as asset failure, or sometimes permit breaches can stem from third parties’ illegal discharges to our sewer network.
The permit for each WRC and WTC details how many samples must be taken each year to monitor the quality of the discharge. The permit also sets out how many samples are allowed to exceed the permit limits – usually three per year. If the samples exceed the permit limits more times than allowed, the site is classed as failing i.e. failing to meet the permit conditions.
For many parameters, permits also state an absolute threshold – if one sample exceeds this limit, the site is classed as failing.
The treatment works compliance PC reports the percentage of our sites that are not failing their permit conditions. This is calculated as:
Note that the EA determines which sites are included in this metric based on site size – the very small WRCs are excluded.
Compliance against discharge permits acts as an indicator of the health and resilience of our WRCs and WTCs and our impact on the environment. This PC incentivises us to maintain and improve these assets so that we can provide a consistent service to current and future generations and safeguard the environment in our region.
Dataset details
The dataset provides details of the failing sites contributing to our performance commitment in each reporting year.
|
Column position |
Column heading |
Description |
Units |
|
1 |
APR reporting year |
The reporting year that this failing site contributes towards, e.g. 2020-2021, 2021-2022.
|
N/A |
|
2 |
Environment Agency permit number
|
The unique identifier code for the permit that was breached. |
N/A |
|
3 |
Site ID |
The numerical Wessex Water code for the site at which the permit was breached.
|
N/A |
|
4 |
Site |
The name for the site in column position 3.
|
N/A |
|
5 |
Site type |
There are two possible entries: ‘Water Recycling Centre’ ‘Water Treatment Centre’
|
N/A |
|
6 |
Calendar year |
The calendar year during which the failure occurred, e.g. 2020, 2021. Failures in the 2020 calendar year contribute to the 2020-21 reporting year, failures in the 2021 calendar year contribute to the 2021-22 reporting year, etc.
|
calendar year |
|
7 |
Reason for site to be determined as failing the permit
|
There are two different entries in this dataset: ‘Look up table sample exceedances’ indicates that the site was classed as failing because samples exceeded the permit limits more times than allowed. This is known as ‘look up table sample exceedance’ because the number of ‘allowed’ exceedances is found in the ‘look up table’ section of the permit. ‘Sample exceedance’ indicates that the site was classed as failing because a single sample exceeded its absolute limit.
|
N/A |
|
8 |
Affected determinand |
The permit details a variety of parameters that need to be measured. This column indicates the parameter that was exceeded to result in the site failure.
|
N/A |
How was this data collated?
At the end of each calendar year the EA produces a list of sites that are classed as failing. The published dataset is an extract from this list, with relevant information added from our internal investigation work.
Data quality
There were no compliance failures in 2021 (reporting year 2021-2022).
Publish frequency
For the remaining years of the 2020-25 period, an additional year of data will be added after the annual reporting period.
Contact
If you have any questions or comments about this data set, please get in touch via opendata@wessexwater.co.uk
Terms of use
This dataset is licensed under CC BY, an open data licence, to make it freely available to other potential customers, stakeholders or interested organisations.
Supplementary information
For those keen to develop a deeper understanding of this dataset, the following additional reading is suggested:
Sample data for influent and effluent at our Water Recycling Centres (WRCs)
About this dataset
| Last updated |
1 day ago
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| Commitments |
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