This is the main river, whose catchment area covers almost 25% of the county. The detailed map has a diagram of that catchment area, which includes its main tributaries: the rivers Eden, Bourne (or Shode), Teise, Beult, Loose and Len.
The River Teise (pronounced tice or teeze) begins in Dunorlan Park in Tunbridge Wells and flows eastwards through Lamberhurst, passing Bayham Abbey. Here the small River Bewl, on which is the reservoir Bewl Water, joins the Teise. The Teise bifurcates 2 km SW of Marden, the minor stream flows directly to Twyford Bridge, Yalding, while the major stream joins the River Beult at Hunton, 1.5 km above Yalding.
The River Beult (pronounced belt) has its several sources west of Ashford, and then flows through Headcorn and where it is joined by the major stream of the Teise. The river enters the Medway at Yalding.