[1] The alternative name Deverill derives from the Brittonic root *duβr, meaning "water", and the adjectival suffix *-(i)ol.

[5] The Wylye rises at Kilmington in the southwestern corner of Wiltshire and then disappears underground, reappearing at Coombe Barn, west of Kingston Deverill.

From here it turns southeast to flow through the Wylye Valley, which skirts the southern edge of Salisbury Plain.

The Wylye is fed by several winterbournes, which commonly dry up completely in the summer, so that the water flow in the river can vary greatly according to the time of year.

There are several components that are used to determine this, including biological status, which looks at the quantity and varieties of invertebrates, angiosperms and fish.