What it means: incidents serious enough to harm wildlife, drinking water or people’s use of the water, from any source: water companies, farms, industry and others. Many incidents are reported by the polluters themselves, so changes in reporting affect the figures. Routine sewage spills from storm overflows are counted separately on the sewage spills card. A change of 5% or more counts.

Source: Defra, Environmental Indicator Framework, theme B (water), indicator B2.