The line chart illustrates the proportion of water in four UK rivers – Wales, Northern Ireland, England, and Scotland – classified as having high chemical standards over a decade starting in 1990.
Overall, Northern Ireland and Wales consistently maintained the highest levels of water purity throughout the years. Meanwhile, both England and Scotland demonstrated noticeable improvements in the percentage of rivers meeting the chemical quality benchmarks during the period.
Focusing on the two regions with the highest water quality levels, in 1990, the percentage of purified water in Wales stood at around 93%, notably higher than Northern Ireland’s approximately 83%. Wales then saw a consistent increase, peaking at about 99% in 1998 before experiencing a gradual decline in water quality over the subsequent years. Similarly, Northern Ireland followed an upward trajectory, with the proportion of water meeting high chemical standards rising to around 97% by 2002, making it the region with the cleanest rivers at that time.
As for the remaining rivers, in 1990, the share of high-quality rivers in England began at roughly 44%, considerably ahead of Scotland at 20%. Although Scotland steadily enhanced its water quality for most of the period, it underwent a sharp decline, dropping to approximately 40% in 2002. In contrast, England displayed the most significant improvement, with its percentage of clean water peaking at 60% before settling at 50% in 2002.