There is a chance that Ofwat could eventually switch from RPI-indexation to a system that employs the Consumer Price Index (CPI) - an unpopular proposal with water groups when it was first suggested in 2009. The CPI measure is based on a geometric, as opposed to an arithmetic mean - and generally produces a lower rate. However, the water companies can take succour from the fact that the present price limits are set until 2020.
