We continue to improve the resilience of supplies to ensure the majority of people can be supplied from more than one source. This builds on work and investment over the last 10 years.
Our ODI target is to reduce the number of customers with a single source of supply from 46.9 per cent to 24.7 per cent between 2015 and 2020. We are currently at 45.3 per cent and are making good progress.
A major resilience scheme for Grafham Water Treatment Works in Cambridgeshire is due to be completed in 2018/19. This will result in a significant reduction in the figure. This and a number of other planned schemes means we are on course to meet the 24.7 per cent target by 2020.
Our region is one of the driest in the country and experiences periodic episodes of drought. We maintain supplies thanks to resilience schemes put in place after previous droughts, the use of drought legislation to take water from rivers under low flows and, occasionally, restrictions on the use of hosepipes.
Customers have told us that they do not expect to face severe restrictions. Our draft 2019 Water Resource Management Plan will promote investment to remove the threat of rota cuts and standpipes and increasing the resilience of our supply system to the impact of severe drought.
We have already committed to an ODI that limits hosepipe bans and other service restrictions to less than once in every 10 years. The last hosepipe ban was in 2012.
We have committed to three planned levels of service that form the basis of our Security of Supply Index (SOSI). These are:
SOSI is used to identify any risk of water shortage within Anglian Water's supply area and is expressed as a score out of 100 for the average day in a dry year, and for periods of peak demand. The area we supply is divided into resource zones and a shortage in any one of these zones would result in a score of less than 100.