What it means: how full England’s main reservoirs were at the end of each month, as reported by the Environment Agency. Levels normally fall through summer and recover in winter, so compare a month with the same month in other years. At the end of September 2026 storage was about 19 points below the long-term average for the time of year, after a dry summer. Reservoirs are only part of supply: much of south and east England relies on groundwater. A change of five points or more on a year earlier counts.

Source: Environment Agency, national water situation reports, monthly summaries.