The call comes after results from a trial revealed discrepancies between the water companies’ data of non-household customers, and the actual number of non-household customers.
In the trial the companies involved – Albion Water, Anglian Water, Cambridge Water, Essex and Suffolk Water, Northumbrian Water, Severn Trent Water, South Staffordshire Water, and Thames Water – used external datasets and a combination of automated and semi-automated methods to identify non-household customers.
A total of 31 per cent of premises in the water company records were not found in the list of non-household properties, while 23 per cent of non-domestic properties were not found in the water company records. The success rate for the companies involved ranged from less than 40 per cent up to more than 95 per cent.
The pilot also highlighted some cases where a single water company recorded covering more than one premises with one account or of several water company records covering a single premises.
The main reasons for the variation within the data were said to be the data structure in the company systems, the historic quality of the data, and the use of different thresholds for what was sufficiently close to be an exact match.
To overcome these issues, Open Water stated each company needs “a clear plan to ensure they can give the market operator and Ofwat the necessary assurances that their non-household data is accurate and complete”.
It added: “Additional steps will be necessary to confirm that all non-household premises have been unambiguously identified for inclusion in the competitive market.
“It is clear that while the automated and semi-automated approach provides a good start, it is not sufficient to provide a robust full match without rigorous validation.”