Major rivers of the United Kingdom

This is a list of the major rivers of the United Kingdom, as being prominent in length, flow volume (discharge rate), or both.

Major rivers of the United Kingdom Rank River Length (miles) Length (km) Mean flow (m3/s) Mouth Country 1 River Severn 220 354 107.4 Severn Estuary Wales/England 2 River Thames 215 346 65.4 Thames Estuary England 3 River Trent 185 297 89.0 The Humber England 4 River Wye 155 250 73.1 Severn Estuary Wales/England 5 River Great Ouse 143 230 15.6 The Wash England 6 River Ure/River Ouse, Yorkshire 129 208 69.8 The Humber England 7 River Tay 117 188 179.0 Firth of Tay Scotland 8 River Clyde 109 176 48.5 Firth of Clyde Scotland 9 River Spey 107 172 65.7 Moray Firth Scotland 10 River Nene 100 161 9.3 The Wash England 11 River Bann / Lough Neagh 99 159 92.2 Atlantic Ocean Northern Ireland 12 River Tweed 96 155 81.7 North Sea Scotland/England 13 River Avon, Warwickshire 96 154 17.3 River Severn* England 14 River Eden, Cumbria 90 145 53.7 Solway Firth England 15 River Dee, Aberdeenshire 87 140 47.8 North Sea Scotland 16 River Witham 82 132 5.2 The Wash England 17 River Teme 81 130 18.2 River Severn* Wales/England 18= River Don, Aberdeenshire 80 129 21.3 North Sea Scotland 18= River Foyle 80 129 58.8 Atlantic Ocean Northern Ireland/Republic of Ireland 20 River Usk 78 125 28.6 Severn Estuary Wales 21 River Teifi- River Teifi - CCW 76 122 29.5 Cardigan Bay Wales 22= River Towy 75 121 39.9 Carmarthen Bay Wales 22= River Ribble 75 120 34.0 Irish Sea England 22= River Avon, Bristol 75 120 22.2 Mouth of the Severn England 25= River Tyne 73 118 45.2 North Sea England 25= River Swale 73 118 20.2 River Ure England 27 River Derwent, Yorkshire 72 115 17.4 River Ouse, Yorkshire England 28= River Aire 71 114 36.5 River Ouse, Yorkshire England 28= River Nith 71 114 36.5 Solway Firth Scotland 30= River Tees 70 113 22.2 North Sea England 30= River Medway 70 113 11.7 Thames Estuary England 30= River Mersey 70 113 37.1 Irish Sea England 33= River Dee, Wales 70 112 34.1 Dee Estuary Wales/England 33= River Don, South Yorkshire 70 112 16.3 River Ouse, Yorkshire England 35 River Ness 68 110 90.7 Beauly Firth Scotland 36= River Welland 65 105 8.72 The Wash England 36= River Wharfe 65 105 17.6 River Ouse, Yorkshire England 38= River Tamar 61 98 22.9 English Channel England 38= River Stour, Dorset 61 98 13.8 Christchurch Harbour England 40= River Avon, Hampshire 60 96 20.0 Christchurch Harbour England 40= River Exe 60 96 25.4 English Channel England 40= River Wear 60 96 14.9 The North Sea England

There seems to be little consensus in published sources as to the lengths of rivers, nor much agreement as to what constitutes a river. Thus the River Ure and River Ouse can be counted as one river system or as two rivers. If it is counted as one, the River Aire/ River Ouse/Humber system would come fourth in the list, with a combined length of . The River Trent/Humber system would top the list with their combined length of .

The Thames tributary, the River Churn, sourced at Seven Springs, adds to the length of the Thames, from its traditional source at Thames Head. The Churn/Thames' length at is therefore greater than the Severn's length of . Thus, the combined Churn/Thames river would top the list. Sue Owen et al., in their book on rivers, generally restrict the length to the parts that bear the same name. Thus the River Nene is quoted at , but would be around more if the variously named sources were included. Many of the above lengths are considerably different from Sue Owen's list, some longer and some shorter.

Where a river ends in an estuary the conventional British approach has been to treat the river as ending at the end of the administrative zone. Thus the Severn ends at the mouth of the Bristol Avon and the Thames at the Yantlet Line. The currently accepted end of the Severn Estuary is about further, and the Port of London's authority stretches now to Margate, further. Other countries have different conventions, making comparisons of limited value. Those rivers which empty into other (non-tidal sections of) rivers are indicated in the table thus*. In Yorkshire, the Aire, Derwent, Don, and Wharfe all empty into a tidal section of the Yorkshire Ouse.

The calculation of mean flow presents its own challenges, relying on sampling at a limited number of gauging stations. The data presented in the table are derived from those offered up by the National River Flow Archive, in particular the flow measured at the lowermost gauging stations on each named watercourse. Sometimes the figures of further downstream tributaries are combined with those of the main stem river to provide a more realistic flow figure for the lowermost non-tidal stretch of a watercourse, this also allows for less pollution.

Major rivers of the United Kingdom

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