The Beane begins life as flow from various chalk springs near the North Hertfordshire hamlet of Roe Green, Sandon, a little way southwest of Royston at the eastern end of the Chiltern Hills. From here the river runs more or less due south until it reaches Hertford where it flows into the River Lea. Along its initial southward journey the river is joined by various tributaries, including the Weston Tributary and the Cottered and Ardeley Brooks as well as various unnamed smaller channels.
The first 10km or so from the source to just north of Walkern is a ‘winterbourne’, meaning that flow tends only seen here during the winter months when groundwater levels and rainfall are at their highest. It can though appear at other times and indeed has tended to flood local roads after cloudbursts. This northern section passes through a sparsely populated mostly agricultural area, and as a result is prone to being affected by run-off from farmland. There are two small sewage treatment works in this upper section, each of which are served by ‘combined sewers’ – systems where rainwater and foul water from buildings share the same pipes to the sewage works. This means that after prolonged heavy rain or periods of high groundwater, the ‘combined sewer overflow’ or CSOs at these works can (and do) discharge some untreated waste. A programme of improvements to the storm tank capacity at these works is underway and will see these overflows become less frequent and eventually stop, but this is a long term project which has already cost in excess of £2million (in 2024) and is due for completion by 2035. There are no other sewage works along the Beane, as they were replaced by a major trunk sewer built during the creation of Stevenage New Town from the 1950s onwards, which carries all the foul waste away to a treatment works at Rye Meads, near Hoddesdon.