F3: Disruption or unwanted impacts caused by drought
Short Description
The indicator focuses on disruption to public water supply due to drought by tracking changes in a Supply Demand Balance Index (SDBI). This indicator was reported by all water and sewerage companies for the first time in Summer 2022 as part of the Environment Agency’s Environmental Performance Assessment (EPA) annual report.
Water companies have a statutory duty to produce a water resources management plan (WRMP) and drought plan. These are prepared, published and maintained in accordance with provisions of the Water Industry Act 1991 and regulations and directions made under it. A WRMP must set out how a company plans to maintain the balance between supply and demand for water over at least the next 25 years. This includes how it will manage the increasing pressures on our water supplies from a growing population and climate change, whilst protecting the environment. A drought plan sets out the operational actions a water company will take before, during and after a drought to maintain a secure supply of water.
Readiness and links to data
This indicator is not available for reporting in 2023 in a finalised form. An interim indicator is presented here highlighting the SDBI status of each water and sewerage company in England. The SDBI measures how a company is realistically able to meet water demand compared to the design drought event that is set out in the company’s WRMP. It will therefore test the theoretical risk that customers could face if there was a drought. In future publications of this indicator, trend information will be provided to track water companies’ performance over time.
Water only companies are being considered for inclusion in the EPA for the 2026 to 2030 data reporting period. The Environmental Performance Assessment report including the SDBI metric results are published annually in July in a performance report. This includes reports on each of the water companies.
Indicator components
Table F3: Supply Demand Balance Index (SDBI) status by water company, 2021/2022
| Water company | Supply demand balance index status |
|---|---|
| Anglian Water | Better than target |
| Northumbrian Water | Better than target |
| Severn Trent Water | Better than target |
| Southern Water | Significantly below target |
| South West Water | Significantly below target |
| Thames Water | Better than target |
| United Utilities | Better than target |
| Wessex Water | Better than target |
| Yorkshire Water | Better than target |
Trend description for F3
In 2021/2022, seven of the nine water and sewage companies in England were assessed to have an SDBI score of 100 and were considered to be operating on or better than target. The remaining two companies, Southern Water and South West Water, achieved a score of less than 99 and were considered to be performing significantly below the target as defined by the WRMP.
Assessment of change
No assessment of change was undertaken for this indicator as there are insufficient data points.