It rises near Broad Hinton in Wiltshire in the West Country of England, and flows in a north and then westerly direction, joining the Avon at Great Somerford.

It flows first in a northerly direction, and then just south of Royal Wootton Bassett it is joined by minor tributaries from Westlea[citation needed] in Swindon and a reservoir at Tockenham Wick.

The stream then passes under the M4 motorway and turns to the west past Brinkworth, joined on the right by the Thunder Brook near Dovey's Farm.

Floating water crowfoot Ranunculus, Desmoulin's whorl snail, the sedge Carex and the reeds Phragmitesand Glyceria maxima.

In addition, "diverse fish assemblages, and [..] varied aquatic invertebrate fauna" are to be found.