Thames Water interim determination of price limit (idok): information provided by all water and sewerage companies which has supported our draft determination

On 16 October 2013, we published our draft determination of Thames Water’s application for an interim determination of its price limit (idok) which it submitted to us on 9 August this year.

In considering Thames Water’s application, we have used comparative information provided by other water and sewerage companies to support our decisions. For transparency, we have published the information that companies submitted where we have ultimately relied on it in making our draft determination. As we state in our draft determination, we consider it is right that all consultees should be able to see these data on a comparable basis.

This information relates our assessment of Thames Water’s claim on private sewers and Thames Water’s claim, and our counter notice, on sewer flooding.

Private Sewers

In August all companies provided information that we had requested to assist us in the price setting process. Whilst we will be publishing the whole of the August data submission in early November, we have used information on private sewers in our assessment and so we have published the subset of data we have used in our draft determination. The information comprises three years of actual data on activity levels and expenditure and forecasts of activity levels for the remaining two years of the price control period.

We have used information from Table 5 that companies included in their August data submissions. We have not published Table 5 in its entirety, just the 17 lines that are relevant to our draft determination.

The complete Table 5 submission for each company will be published in November, at the same time as other tables from the August data submission.

Sewer Flooding

In order for us to consider the sewer flooding element of Thames Water’s claim, and our counter notice, we asked all water and sewerage companies to provide us with additional comparative information about sewer flooding investment programmes.

We asked companies to provide information on the following.

  • The total number of properties which have flooded and are deemed to be at risk of flooding more than once in ten years and twice in ten years at the end of the year.
  • The number of properties added to 1 in 10 and 2 in 10 registers following a flooding incident.
  • The number of properties removed from the 1 in 10 and 2 in 10 registers because of better information. This category includes:
    1. changes resulting from better quality information such as improved knowledge of the sewerage system (for example extended modelling, better estimates of figures)
    2. properties previously thought to have been at risk but where investigation has subsequently shown the problem to have been caused by reasons other than overloading (for example, a blockage or collapse)
    3. properties which were incorrectly identified as being at risk in previous years.
  • The number of properties removed from the 1 in 10 and 2 in 10 registers by company action.

We asked companies to provide information for the years 2011-12 to 2014-15, as companies had already reported information to us for 2010-11 in June 2011. Data for 2013-14 and 2014-15 is subject to current company forecasts.

We also asked that if a company expected outturn performance to vary significantly from the output allowed for 2010-15 price limits, that it should provide a brief description of the drivers for this.

We are grateful for the companies’ co-operation in providing this in a short time frame while they are busy preparing business plans.