MOSL has launched the first phase of the Data Cleanse Service.

The Market Eligibility Assurance Review phase is the first of four deliverables for 2023/24. It involves trading parties reviewing and assuring or deregistering supply points that are considered ineligible for the market.

From today, trading parties will have access to CMOS data which has been grouped as assurance levels 1, 2 or 3. Whilst trading parties have access to the entirety of their data, they are only required to review the Level 1 supply points (those that are highly likely to be ineligible for the market) within 12 months.

The assurance levels have been determined by criteria created by our service provider Sagacity and have been subject to rigorous testing by the Data Cleanse Service Working Group (DCSWG) during the pilot process, which began in August. 

The CMOS data files are available for trading parties via a new functionality within My MOSL, called My Files.

For more information on the process and how to access the files, please see the technical specification document. This document outlines the responsibilities of wholesalers and retailers, and at what stage they should align to jointly assure and/or de-register supply points from the non-household market. It also includes process flow diagrams, an example of the file format that trading parties will receive and information on the reporting that will be provided.

In response to trading party feedback, we will also be also publishing a best practice guide shortly. This document will outline expected best practice from trading parties. It will also highlight relevant areas of the Wholesale-Retail Code (WRC) and existing codes of practice, in relation to areas such as deregistration, settlement and retail billing. The document is being created in conjunction with Ofwat and CCW and will be updated as the programme progresses.

Matt Labrum, Programme Lead, says: "We are so pleased to have launched the first phase of the Data Cleanse Service. By giving trading parties access to this segmented data, we're predicting that this exercise could remove over 10,000 ineligible supply points from the non-household water market. This brings us a step closer to getting accurate and reliable data in the central system and improving the experience for non-household customers. We acknowledge that reviewing and assuring or deregistering these supply points requires time and resources, but believe the benefits of getting better data far outweigh the effort. This phase is the first and fundamental step to improving and assuring data for the long-term benefit of market participants and their customers."

Progress on trading parties' review of the data will be displayed at a market level via a dashboard on the MOSL website from the beginning of 2024.

If you require technical support, please contact IT Support via My MOSL. For media enquiries, please email This email address is being protected from spambots. You need JavaScript enabled to view it.

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