The River Tillingbourne (also known as the Tilling Bourne) runs along the south side of the North Downs and joins the River Wey at Guildford. Its source is near Tilling Springs to the north of Leith Hill at grid reference TQ143437 and it runs through Friday Street, Abinger Hammer, Gomshall, Shere, Albury, Chilworth and Shalford. The source is a semi-natural uninhabited area. The catchment is situated on sandstone which has a low rate of weathering.