Silent Pool is a spring-fed lake at the foot of the North Downs, about 4 miles (6 km) east of Guildford in Surrey. The outflow from Silent Pool runs into a second, adjacent, lake, Sherbourne Pond, created in the mid-seventeenth century. In turn the outflow from the Sherbourne Pond feeds the Sherbourne Brook, a tributary of the Tilling Bourne.

The River Tillingbourne runs along the south side of the North Downs and joins the River Wey at Guildford. Its source is a mile south of 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. The Tillingbourne is 24 km (15 mi) in length.