Much of the water that enters the Estate through run-off comes from neighbouring intensive farms, roads and built-up areas and therefore contains significant amounts of pollution.
However, water-testing in 2016 gave all standing water on the Estate the highest reading for water purity, indicating that our land is now providing an effective system of filtration and purification.
Dragonflies and mayflies are particularly susceptible to water pollution and the rise in populations of these species at Knepp (including the scarce chaser - an incredibly rare blue-eyed dragonfly
found only in six places in the UK) are good indicators of water quality. As are rare plants like water-violet and lesser water parsnip that are also now expanding in water bodies across the Estate.