The River Hart is a tributary of the River Whitewater in north Hampshire, England. It rises at Ashley Head spring in Crondall and flows north to meet the Whitewater at Bramshill.

The River Whitewater rises at springs near Bidden Grange Farm between Upton Grey and Greywell in Hampshire, England. It flows northeast and is a tributary of the River Blackwater near Swallowfield. Its headwaters flow over chalk and there is little pollution making the River Whitewater rich in wildlife. It was noted on Jansson's map of Hampshire of 1646.