Reliability and availability

We use a wide variety of other information to assess risks to customers – and decide whether we need to take action on your behalf. This is part of our approach for holding water companies to account.

Below we highlight the overall performance of the monopoly water and sewerage and water only companies in England and Wales in 2014-15 – and any action we are taking to protect customers’ interests.

Reliability and availability indicators

In 2014-15, all of the companies met their targets for reducing water leaks from their networks. The overall level of leakage, although marginally higher than in 2013-14, was still around its lowest level since records began in the early 1990s.

During 2014-15 there were no restrictions in place on water use. Overall, companies were able to provide us with reassurance that they were able to supply enough water to meet their customers’ needs. Find out more about why water companies sometimes need to restrict water supplies.

Each company is required to maintain its assets (such as water and sewerage treatment works, and underground networks of water mains and sewers) to a certain standard so that it can provide reliable services to you over the long term ‒ and protect the environment. We call this ‘stable serviceability’.

When a company is not maintaining its assets effectively, there will be a rise in the number of incidents such as burst water mains or sewers overflowing. So it is important they get it right.

Companies have told us that overall they maintained their assets to a sufficient standard in 2014-15.

Action we are taking

Companies that had less than stable (‘marginal’ or ‘deteriorating’) serviceability are seeking to restore assets to stable serviceability. We reviewed their progress with these action plans as part of the 2014 price review. This included clawing back £149m for customers where companies had not restored their performance. Clawing back this money will lower future bills, to make sure it is shareholders pay out when customers have not received the level of service they have paid for. We will also assess next year whether there is a case to claw back any further money for customers, following a review of all company data from 2014-15.

You can read more about this in our draft determinations and in our PR14 reconciliation rulebook policy document.


We have collated below the performance data companies have published.

Serviceability water non-infrastructureServiceability water infrastructureServiceability for sewerage non-infrastructureServiceability sewerage infrastructureLeakageSecurity of supply index (SoSI)
NorthumbrianNorthumbria areaSTABLESTABLESTABLESTABLE137100
Essex and Suffolk area61100
Affinity WaterCentral areaSTABLESTABLE172100
Southeast areaSTABLESTABLE7
South Staffordshire – Cambridge areaSTABLESTABLE14100
South Staffordshire – South Staffs areaSTABLESTABLE69100
Sutton & East SurreySTABLESTABLE24100

Green means the company’s performance is in line with or better than expected
Amber means the company’s performance is not in line with expectations but performance has slipped only slightly
Red means the company’s performance is significantly below target or expectation
Grey means companies did not have to submit this data