Metric permalink
Storm overflow spill duration (England)
Part of the Environment and Climate domain. Total hours of storm overflow discharges from monitored assets in England per year, measuring the scale of sewage pollution of rivers and coastal waters.
Latest data
Latest reading
2025
A higher reading is treated as worse for this indicator.
Score composition
Stress score
Blended from three components: (60% weight), trend (30% weight) and volatility (10% weight). Full formula on the methodology page.
Level · 60% weight
Bounds: scored against fixed best/worst limits, used until a metric has about eight years of verified data to rank against.
Trend · 30% weight
Measured from the direction and size of the change between the two most recent readings.
Volatility · 10% weight
50Provisional: fewer than four historical readings are available, so this defaults to a mid range score rather than a measured figure.
Data confidence and provenance
Confidence and source
How much weight to put on the reading, the mean data-confidence across the component metrics (source quality, recency and completeness).
Source
Event Duration Monitoring, storm overflow annual returns
- Update frequency
- Annual
- Reliability
- medium
Provenance
- Provider
- Environment Agency
- Series ID
- storm overflow spill duration, England
- Frequency
- annual
- Accessed
- 23 June 2026
Known weakness
Event Duration Monitors have increased coverage over time, meaning rising totals may partly reflect improved monitoring rather than worsening environmental performance.
Notes
Verified official value from Environment Agency (storm overflow spill duration, England), accessed 2026-06-23.
Historical values
History
| Period | Value | Relative |
|---|---|---|
| 2023 | 3.61 | |
| 2024 | 3.61 | |
| 2025 | 1.87 |